aboutsummaryrefslogtreecommitdiffstats
path: root/activerecord/lib/active_record/base.rb
blob: 2df1024a1b1820fab59cc93ff6fdaa39e0acca1a (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
1277
1278
1279
1280
1281
1282
1283
1284
1285
1286
1287
1288
1289
1290
1291
1292
1293
1294
1295
1296
1297
1298
1299
1300
1301
1302
1303
1304
1305
1306
1307
1308
1309
1310
1311
1312
1313
1314
1315
1316
1317
1318
1319
1320
1321
1322
1323
1324
1325
1326
1327
1328
1329
1330
1331
1332
1333
1334
1335
1336
1337
1338
1339
1340
1341
1342
1343
1344
1345
1346
1347
1348
1349
1350
1351
1352
1353
1354
1355
1356
1357
1358
1359
1360
1361
1362
1363
1364
1365
1366
1367
1368
1369
1370
1371
1372
1373
1374
1375
1376
1377
1378
1379
1380
1381
1382
1383
1384
1385
1386
1387
1388
1389
1390
1391
1392
1393
1394
1395
1396
1397
1398
1399
1400
1401
1402
1403
1404
1405
1406
1407
1408
1409
1410
1411
1412
1413
1414
1415
1416
1417
1418
1419
1420
1421
1422
1423
1424
1425
1426
1427
1428
1429
1430
1431
1432
1433
1434
1435
1436
1437
1438
1439
1440
1441
1442
1443
1444
1445
1446
1447
1448
1449
1450
1451
1452
1453
1454
1455
1456
1457
1458
1459
1460
1461
1462
1463
1464
1465
1466
1467
1468
1469
1470
1471
1472
1473
1474
1475
1476
1477
1478
1479
1480
1481
1482
1483
1484
1485
1486
1487
1488
1489
1490
1491
1492
1493
1494
1495
1496
1497
1498
1499
1500
1501
1502
1503
1504
1505
1506
1507
1508
1509
1510
1511
1512
1513
1514
1515
1516
1517
1518
1519
1520
1521
1522
1523
1524
1525
1526
1527
1528
1529
1530
1531
1532
1533
1534
1535
1536
1537
1538
1539
1540
1541
1542
1543
1544
1545
1546
1547
1548
1549
1550
1551
1552
1553
1554
1555
1556
1557
1558
1559
1560
1561
1562
1563
1564
1565
1566
1567
1568
1569
1570
1571
1572
1573
1574
1575
1576
1577
1578
1579
1580
1581
1582
1583
1584
1585
1586
1587
1588
1589
1590
1591
1592
1593
1594
1595
1596
1597
1598
1599
1600
1601
1602
1603
1604
1605
1606
1607
1608
1609
1610
1611
1612
1613
1614
1615
1616
1617
1618
1619
1620
1621
1622
1623
1624
1625
1626
1627
1628
1629
1630
1631
1632
1633
1634
1635
1636
1637
1638
1639
1640
1641
1642
1643
1644
1645
1646
1647
1648
1649
1650
1651
1652
1653
1654
1655
1656
1657
1658
1659
1660
1661
1662
1663
1664
1665
1666
1667
1668
1669
1670
1671
1672
1673
1674
1675
1676
1677
1678
1679
1680
1681
1682
1683
1684
1685
1686
1687
1688
1689
1690
1691
1692
1693
1694
1695
1696
1697
1698
1699
1700
1701
1702
1703
1704
1705
1706
1707
1708
1709
1710
1711
1712
1713
1714
1715
1716
1717
1718
1719
1720
1721
1722
1723
1724
1725
1726
1727
1728
1729
1730
1731
1732
1733
1734
1735
1736
1737
1738
1739
1740
1741
1742
1743
1744
1745
1746
1747
1748
1749
1750
1751
1752
1753
1754
1755
1756
1757
1758
1759
1760
1761
1762
1763
1764
1765
1766
1767
1768
1769
1770
1771
1772
1773
1774
1775
1776
1777
1778
1779
1780
1781
1782
1783
1784
1785
1786
1787
1788
1789
1790
1791
1792
1793
1794
1795
1796
1797
1798
1799
1800
1801
1802
1803
1804
1805
1806
1807
1808
1809
1810
1811
1812
1813
1814
1815
1816
1817
1818
1819
1820
1821
1822
1823
1824
1825
1826
1827
1828
1829
1830
1831
1832
1833
1834
1835
1836
1837
1838
1839
1840
1841
1842
1843
1844
1845
1846
1847
1848
1849
1850
1851
1852
1853
1854
1855
1856
1857
1858
1859
1860
1861
1862
1863
1864
1865
1866
1867
1868
1869
1870
1871
1872
1873
1874
1875
1876
1877
1878
1879
1880
1881
1882
1883
1884
1885
1886
1887
1888
1889
1890
1891
1892
1893
1894
1895
1896
1897
1898
1899
1900
1901
1902
1903
1904
1905
1906
1907
1908
1909
1910
1911
1912
1913
1914
1915
1916
1917
1918
1919
1920
1921
1922
1923
1924
1925
1926
1927
1928
1929
1930
1931
1932
1933
1934
1935
1936
1937
1938
1939
1940
1941
1942
1943
1944
1945
1946
1947
1948
1949
1950
1951
1952
1953
1954
1955
1956
1957
1958
1959
1960
1961
1962
1963
1964
1965
1966
1967
1968
1969
1970
1971
1972
1973
1974
1975
1976
1977
1978
1979
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026
2027
2028
2029
2030
2031
2032
2033
2034
2035
2036
2037
2038
2039
2040
2041
2042
2043
2044
2045
2046
2047
2048
2049
2050
2051
2052
2053
2054
2055
2056
2057
2058
2059
2060
2061
2062
2063
2064
2065
2066
2067
2068
2069
2070
2071
2072
2073
2074
2075
2076
2077
2078
2079
2080
2081
2082
2083
2084
2085
2086
2087
2088
2089
2090
2091
2092
2093
2094
2095
2096
2097
2098
2099
2100
2101
2102
2103
2104
2105
2106
2107
2108
2109
2110
2111
2112
2113
2114
2115
2116
2117
2118
2119
2120
2121
2122
2123
2124
2125
2126
2127
2128
2129
2130
2131
2132
2133
2134
2135
2136
2137
2138
2139
2140
2141
2142
2143
2144
2145
2146
2147
2148
2149
2150
2151
2152
2153
2154
2155
2156
2157
2158
2159
2160
2161
2162
2163
2164
2165
2166
2167
2168
2169
2170
2171
2172
2173
2174
2175
2176
2177
2178
2179
2180
2181
2182
2183
2184
2185
2186
2187
2188
2189
2190
2191
2192
2193
2194
2195
2196
2197
2198
2199
2200
2201
2202
2203
2204
2205
2206
2207
2208
2209
2210
2211
2212
2213
2214
2215
2216
2217
2218
2219
2220
2221
2222
2223
2224
2225
2226
2227
2228
2229
2230
2231
2232
2233
2234
2235
2236
2237
2238
2239
2240
2241
2242
2243
2244
require 'yaml'
require 'set'
require 'active_support/benchmarkable'
require 'active_support/dependencies'
require 'active_support/time'
require 'active_support/core_ext/class/attribute_accessors'
require 'active_support/core_ext/class/delegating_attributes'
require 'active_support/core_ext/class/inheritable_attributes'
require 'active_support/core_ext/array/extract_options'
require 'active_support/core_ext/hash/deep_merge'
require 'active_support/core_ext/hash/indifferent_access'
require 'active_support/core_ext/hash/slice'
require 'active_support/core_ext/string/behavior'
require 'active_support/core_ext/kernel/singleton_class'
require 'active_support/core_ext/module/delegation'
require 'active_support/core_ext/object/duplicable'
require 'active_support/core_ext/object/blank'
require 'arel'
require 'active_record/errors'

module ActiveRecord #:nodoc:
  # Active Record objects don't specify their attributes directly, but rather infer them from the table definition with
  # which they're linked. Adding, removing, and changing attributes and their type is done directly in the database. Any change
  # is instantly reflected in the Active Record objects. The mapping that binds a given Active Record class to a certain
  # database table will happen automatically in most common cases, but can be overwritten for the uncommon ones.
  #
  # See the mapping rules in table_name and the full example in link:files/README.html for more insight.
  #
  # == Creation
  #
  # Active Records accept constructor parameters either in a hash or as a block. The hash method is especially useful when
  # you're receiving the data from somewhere else, like an HTTP request. It works like this:
  #
  #   user = User.new(:name => "David", :occupation => "Code Artist")
  #   user.name # => "David"
  #
  # You can also use block initialization:
  #
  #   user = User.new do |u|
  #     u.name = "David"
  #     u.occupation = "Code Artist"
  #   end
  #
  # And of course you can just create a bare object and specify the attributes after the fact:
  #
  #   user = User.new
  #   user.name = "David"
  #   user.occupation = "Code Artist"
  #
  # == Conditions
  #
  # Conditions can either be specified as a string, array, or hash representing the WHERE-part of an SQL statement.
  # The array form is to be used when the condition input is tainted and requires sanitization. The string form can
  # be used for statements that don't involve tainted data. The hash form works much like the array form, except
  # only equality and range is possible. Examples:
  #
  #   class User < ActiveRecord::Base
  #     def self.authenticate_unsafely(user_name, password)
  #       where("user_name = '#{user_name}' AND password = '#{password}'").first
  #     end
  #
  #     def self.authenticate_safely(user_name, password)
  #       where("user_name = ? AND password = ?", user_name, password).first
  #     end
  #
  #     def self.authenticate_safely_simply(user_name, password)
  #       where(:user_name => user_name, :password => password).first
  #     end
  #   end
  #
  # The <tt>authenticate_unsafely</tt> method inserts the parameters directly into the query and is thus susceptible to SQL-injection
  # attacks if the <tt>user_name</tt> and +password+ parameters come directly from an HTTP request. The <tt>authenticate_safely</tt>  and
  # <tt>authenticate_safely_simply</tt> both will sanitize the <tt>user_name</tt> and +password+ before inserting them in the query,
  # which will ensure that an attacker can't escape the query and fake the login (or worse).
  #
  # When using multiple parameters in the conditions, it can easily become hard to read exactly what the fourth or fifth
  # question mark is supposed to represent. In those cases, you can resort to named bind variables instead. That's done by replacing
  # the question marks with symbols and supplying a hash with values for the matching symbol keys:
  #
  #   Company.where(
  #     "id = :id AND name = :name AND division = :division AND created_at > :accounting_date",
  #     { :id => 3, :name => "37signals", :division => "First", :accounting_date => '2005-01-01' }
  #   ).first
  #
  # Similarly, a simple hash without a statement will generate conditions based on equality with the SQL AND
  # operator. For instance:
  #
  #   Student.where(:first_name => "Harvey", :status => 1)
  #   Student.where(params[:student])
  #
  # A range may be used in the hash to use the SQL BETWEEN operator:
  #
  #   Student.where(:grade => 9..12)
  #
  # An array may be used in the hash to use the SQL IN operator:
  #
  #   Student.where(:grade => [9,11,12])
  #
  # When joining tables, nested hashes or keys written in the form 'table_name.column_name' can be used to qualify the table name of a
  # particular condition. For instance:
  #
  #   Student.joins(:schools).where(:schools => { :type => 'public' })
  #   Student.joins(:schools).where('schools.type' => 'public' )
  #
  # == Overwriting default accessors
  #
  # All column values are automatically available through basic accessors on the Active Record object, but sometimes you
  # want to specialize this behavior. This can be done by overwriting the default accessors (using the same
  # name as the attribute) and calling <tt>read_attribute(attr_name)</tt> and <tt>write_attribute(attr_name, value)</tt> to actually change things.
  # Example:
  #
  #   class Song < ActiveRecord::Base
  #     # Uses an integer of seconds to hold the length of the song
  #
  #     def length=(minutes)
  #       write_attribute(:length, minutes.to_i * 60)
  #     end
  #
  #     def length
  #       read_attribute(:length) / 60
  #     end
  #   end
  #
  # You can alternatively use <tt>self[:attribute]=(value)</tt> and <tt>self[:attribute]</tt> instead of <tt>write_attribute(:attribute, value)</tt> and
  # <tt>read_attribute(:attribute)</tt> as a shorter form.
  #
  # == Attribute query methods
  #
  # In addition to the basic accessors, query methods are also automatically available on the Active Record object.
  # Query methods allow you to test whether an attribute value is present.
  #
  # For example, an Active Record User with the <tt>name</tt> attribute has a <tt>name?</tt> method that you can call
  # to determine whether the user has a name:
  #
  #   user = User.new(:name => "David")
  #   user.name? # => true
  #
  #   anonymous = User.new(:name => "")
  #   anonymous.name? # => false
  #
  # == Accessing attributes before they have been typecasted
  #
  # Sometimes you want to be able to read the raw attribute data without having the column-determined typecast run its course first.
  # That can be done by using the <tt><attribute>_before_type_cast</tt> accessors that all attributes have. For example, if your Account model
  # has a <tt>balance</tt> attribute, you can call <tt>account.balance_before_type_cast</tt> or <tt>account.id_before_type_cast</tt>.
  #
  # This is especially useful in validation situations where the user might supply a string for an integer field and you want to display
  # the original string back in an error message. Accessing the attribute normally would typecast the string to 0, which isn't what you
  # want.
  #
  # == Dynamic attribute-based finders
  #
  # Dynamic attribute-based finders are a cleaner way of getting (and/or creating) objects by simple queries without turning to SQL. They work by
  # appending the name of an attribute to <tt>find_by_</tt>, <tt>find_last_by_</tt>, or <tt>find_all_by_</tt>, so you get finders like <tt>Person.find_by_user_name</tt>,
  # <tt>Person.find_all_by_last_name</tt>, and <tt>Payment.find_by_transaction_id</tt>. So instead of writing
  # <tt>Person.where(:user_name => user_name).first</tt>, you just do <tt>Person.find_by_user_name(user_name)</tt>.
  # And instead of writing <tt>Person.where(:last_name => last_name).all</tt>, you just do <tt>Person.find_all_by_last_name(last_name)</tt>.
  #
  # It's also possible to use multiple attributes in the same find by separating them with "_and_", so you get finders like
  # <tt>Person.find_by_user_name_and_password</tt> or even <tt>Payment.find_by_purchaser_and_state_and_country</tt>. So instead of writing
  # <tt>Person.where(:user_name => user_name, :password => password).first</tt>, you just do
  # <tt>Person.find_by_user_name_and_password(user_name, password)</tt>.
  #
  # It's even possible to call these dynamic finder methods on relations and named scopes. For example :
  #
  #   Payment.order("created_on").find_all_by_amount(50)
  #   Payment.pending.find_last_by_amount(100)
  #
  # The same dynamic finder style can be used to create the object if it doesn't already exist. This dynamic finder is called with
  # <tt>find_or_create_by_</tt> and will return the object if it already exists and otherwise creates it, then returns it. Protected attributes won't be set unless they are given in a block. For example:
  #
  #   # No 'Summer' tag exists
  #   Tag.find_or_create_by_name("Summer") # equal to Tag.create(:name => "Summer")
  #
  #   # Now the 'Summer' tag does exist
  #   Tag.find_or_create_by_name("Summer") # equal to Tag.find_by_name("Summer")
  #
  #   # Now 'Bob' exist and is an 'admin'
  #   User.find_or_create_by_name('Bob', :age => 40) { |u| u.admin = true }
  #
  # Use the <tt>find_or_initialize_by_</tt> finder if you want to return a new record without saving it first. Protected attributes won't be set unless they are given in a block. For example:
  #
  #   # No 'Winter' tag exists
  #   winter = Tag.find_or_initialize_by_name("Winter")
  #   winter.new_record? # true
  #
  # To find by a subset of the attributes to be used for instantiating a new object, pass a hash instead of
  # a list of parameters. For example:
  #
  #   Tag.find_or_create_by_name(:name => "rails", :creator => current_user)
  #
  # That will either find an existing tag named "rails", or create a new one while setting the user that created it.
  #
  # == Saving arrays, hashes, and other non-mappable objects in text columns
  #
  # Active Record can serialize any object in text columns using YAML. To do so, you must specify this with a call to the class method +serialize+.
  # This makes it possible to store arrays, hashes, and other non-mappable objects without doing any additional work. Example:
  #
  #   class User < ActiveRecord::Base
  #     serialize :preferences
  #   end
  #
  #   user = User.create(:preferences => { "background" => "black", "display" => large })
  #   User.find(user.id).preferences # => { "background" => "black", "display" => large }
  #
  # You can also specify a class option as the second parameter that'll raise an exception if a serialized object is retrieved as a
  # descendant of a class not in the hierarchy. Example:
  #
  #   class User < ActiveRecord::Base
  #     serialize :preferences, Hash
  #   end
  #
  #   user = User.create(:preferences => %w( one two three ))
  #   User.find(user.id).preferences    # raises SerializationTypeMismatch
  #
  # == Single table inheritance
  #
  # Active Record allows inheritance by storing the name of the class in a column that by default is named "type" (can be changed
  # by overwriting <tt>Base.inheritance_column</tt>). This means that an inheritance looking like this:
  #
  #   class Company < ActiveRecord::Base; end
  #   class Firm < Company; end
  #   class Client < Company; end
  #   class PriorityClient < Client; end
  #
  # When you do <tt>Firm.create(:name => "37signals")</tt>, this record will be saved in the companies table with type = "Firm". You can then
  # fetch this row again using <tt>Company.where(:name => '37signals').first</tt> and it will return a Firm object.
  #
  # If you don't have a type column defined in your table, single-table inheritance won't be triggered. In that case, it'll work just
  # like normal subclasses with no special magic for differentiating between them or reloading the right type with find.
  #
  # Note, all the attributes for all the cases are kept in the same table. Read more:
  # http://www.martinfowler.com/eaaCatalog/singleTableInheritance.html
  #
  # == Connection to multiple databases in different models
  #
  # Connections are usually created through ActiveRecord::Base.establish_connection and retrieved by ActiveRecord::Base.connection.
  # All classes inheriting from ActiveRecord::Base will use this connection. But you can also set a class-specific connection.
  # For example, if Course is an ActiveRecord::Base, but resides in a different database, you can just say <tt>Course.establish_connection</tt>
  # and Course and all of its subclasses will use this connection instead.
  #
  # This feature is implemented by keeping a connection pool in ActiveRecord::Base that is a Hash indexed by the class. If a connection is
  # requested, the retrieve_connection method will go up the class-hierarchy until a connection is found in the connection pool.
  #
  # == Exceptions
  #
  # * ActiveRecordError - Generic error class and superclass of all other errors raised by Active Record.
  # * AdapterNotSpecified - The configuration hash used in <tt>establish_connection</tt> didn't include an
  #   <tt>:adapter</tt> key.
  # * AdapterNotFound - The <tt>:adapter</tt> key used in <tt>establish_connection</tt> specified a non-existent adapter
  #   (or a bad spelling of an existing one).
  # * AssociationTypeMismatch - The object assigned to the association wasn't of the type specified in the association definition.
  # * SerializationTypeMismatch - The serialized object wasn't of the class specified as the second parameter.
  # * ConnectionNotEstablished+ - No connection has been established. Use <tt>establish_connection</tt> before querying.
  # * RecordNotFound - No record responded to the +find+ method. Either the row with the given ID doesn't exist
  #   or the row didn't meet the additional restrictions. Some +find+ calls do not raise this exception to signal
  #   nothing was found, please check its documentation for further details.
  # * StatementInvalid - The database server rejected the SQL statement. The precise error is added in the message.
  # * MultiparameterAssignmentErrors - Collection of errors that occurred during a mass assignment using the
  #   <tt>attributes=</tt> method. The +errors+ property of this exception contains an array of AttributeAssignmentError
  #   objects that should be inspected to determine which attributes triggered the errors.
  # * AttributeAssignmentError - An error occurred while doing a mass assignment through the <tt>attributes=</tt> method.
  #   You can inspect the +attribute+ property of the exception object to determine which attribute triggered the error.
  #
  # *Note*: The attributes listed are class-level attributes (accessible from both the class and instance level).
  # So it's possible to assign a logger to the class through <tt>Base.logger=</tt> which will then be used by all
  # instances in the current object space.
  class Base
    ##
    # :singleton-method:
    # Accepts a logger conforming to the interface of Log4r or the default Ruby 1.8+ Logger class, which is then passed
    # on to any new database connections made and which can be retrieved on both a class and instance level by calling +logger+.
    cattr_accessor :logger, :instance_writer => false

    def self.inherited(child) #:nodoc:
      @@subclasses[self] ||= []
      @@subclasses[self] << child
      super
    end

    def self.reset_subclasses #:nodoc:
      nonreloadables = []
      subclasses.each do |klass|
        unless ActiveSupport::Dependencies.autoloaded? klass
          nonreloadables << klass
          next
        end
        klass.instance_variables.each { |var| klass.send(:remove_instance_variable, var) }
        klass.instance_methods(false).each { |m| klass.send :undef_method, m }
      end
      @@subclasses = {}
      nonreloadables.each { |klass| (@@subclasses[klass.superclass] ||= []) << klass }
    end

    @@subclasses = {}

    ##
    # :singleton-method:
    # Contains the database configuration - as is typically stored in config/database.yml -
    # as a Hash.
    #
    # For example, the following database.yml...
    #
    #   development:
    #     adapter: sqlite3
    #     database: db/development.sqlite3
    #
    #   production:
    #     adapter: sqlite3
    #     database: db/production.sqlite3
    #
    # ...would result in ActiveRecord::Base.configurations to look like this:
    #
    #   {
    #      'development' => {
    #         'adapter'  => 'sqlite3',
    #         'database' => 'db/development.sqlite3'
    #      },
    #      'production' => {
    #         'adapter'  => 'sqlite3',
    #         'database' => 'db/production.sqlite3'
    #      }
    #   }
    cattr_accessor :configurations, :instance_writer => false
    @@configurations = {}

    ##
    # :singleton-method:
    # Accessor for the prefix type that will be prepended to every primary key column name. The options are :table_name and
    # :table_name_with_underscore. If the first is specified, the Product class will look for "productid" instead of "id" as
    # the primary column. If the latter is specified, the Product class will look for "product_id" instead of "id". Remember
    # that this is a global setting for all Active Records.
    cattr_accessor :primary_key_prefix_type, :instance_writer => false
    @@primary_key_prefix_type = nil

    ##
    # :singleton-method:
    # Accessor for the name of the prefix string to prepend to every table name. So if set to "basecamp_", all
    # table names will be named like "basecamp_projects", "basecamp_people", etc. This is a convenient way of creating a namespace
    # for tables in a shared database. By default, the prefix is the empty string.
    #
    # If you are organising your models within modules you can add a prefix to the models within a namespace by defining
    # a singleton method in the parent module called table_name_prefix which returns your chosen prefix.
    cattr_accessor :table_name_prefix, :instance_writer => false
    @@table_name_prefix = ""

    ##
    # :singleton-method:
    # Works like +table_name_prefix+, but appends instead of prepends (set to "_basecamp" gives "projects_basecamp",
    # "people_basecamp"). By default, the suffix is the empty string.
    cattr_accessor :table_name_suffix, :instance_writer => false
    @@table_name_suffix = ""

    ##
    # :singleton-method:
    # Indicates whether table names should be the pluralized versions of the corresponding class names.
    # If true, the default table name for a Product class will be +products+. If false, it would just be +product+.
    # See table_name for the full rules on table/class naming. This is true, by default.
    cattr_accessor :pluralize_table_names, :instance_writer => false
    @@pluralize_table_names = true

    ##
    # :singleton-method:
    # Determines whether to use Time.local (using :local) or Time.utc (using :utc) when pulling dates and times from the database.
    # This is set to :local by default.
    cattr_accessor :default_timezone, :instance_writer => false
    @@default_timezone = :local

    ##
    # :singleton-method:
    # Specifies the format to use when dumping the database schema with Rails'
    # Rakefile.  If :sql, the schema is dumped as (potentially database-
    # specific) SQL statements.  If :ruby, the schema is dumped as an
    # ActiveRecord::Schema file which can be loaded into any database that
    # supports migrations.  Use :ruby if you want to have different database
    # adapters for, e.g., your development and test environments.
    cattr_accessor :schema_format , :instance_writer => false
    @@schema_format = :ruby

    ##
    # :singleton-method:
    # Specify whether or not to use timestamps for migration versions
    cattr_accessor :timestamped_migrations , :instance_writer => false
    @@timestamped_migrations = true

    # Determine whether to store the full constant name including namespace when using STI
    superclass_delegating_accessor :store_full_sti_class
    self.store_full_sti_class = true

    # Stores the default scope for the class
    class_inheritable_accessor :default_scoping, :instance_writer => false
    self.default_scoping = []

    class << self # Class methods
      def colorize_logging(*args)
        ActiveSupport::Deprecation.warn "ActiveRecord::Base.colorize_logging and " <<
          "config.active_record.colorize_logging are deprecated. Please use " <<
          "Rails::LogSubscriber.colorize_logging or config.colorize_logging instead", caller
      end
      alias :colorize_logging= :colorize_logging

      delegate :find, :first, :last, :all, :destroy, :destroy_all, :exists?, :delete, :delete_all, :update, :update_all, :to => :scoped
      delegate :find_each, :find_in_batches, :to => :scoped
      delegate :select, :group, :order, :limit, :joins, :where, :preload, :eager_load, :includes, :from, :lock, :readonly, :having, :to => :scoped
      delegate :count, :average, :minimum, :maximum, :sum, :calculate, :to => :scoped

      # Executes a custom SQL query against your database and returns all the results.  The results will
      # be returned as an array with columns requested encapsulated as attributes of the model you call
      # this method from.  If you call <tt>Product.find_by_sql</tt> then the results will be returned in
      # a Product object with the attributes you specified in the SQL query.
      #
      # If you call a complicated SQL query which spans multiple tables the columns specified by the
      # SELECT will be attributes of the model, whether or not they are columns of the corresponding
      # table.
      #
      # The +sql+ parameter is a full SQL query as a string.  It will be called as is, there will be
      # no database agnostic conversions performed.  This should be a last resort because using, for example,
      # MySQL specific terms will lock you to using that particular database engine or require you to
      # change your call if you switch engines.
      #
      # ==== Examples
      #   # A simple SQL query spanning multiple tables
      #   Post.find_by_sql "SELECT p.title, c.author FROM posts p, comments c WHERE p.id = c.post_id"
      #   > [#<Post:0x36bff9c @attributes={"title"=>"Ruby Meetup", "first_name"=>"Quentin"}>, ...]
      #
      #   # You can use the same string replacement techniques as you can with ActiveRecord#find
      #   Post.find_by_sql ["SELECT title FROM posts WHERE author = ? AND created > ?", author_id, start_date]
      #   > [#<Post:0x36bff9c @attributes={"first_name"=>"The Cheap Man Buys Twice"}>, ...]
      def find_by_sql(sql)
        connection.select_all(sanitize_sql(sql), "#{name} Load").collect! { |record| instantiate(record) }
      end

      # Creates an object (or multiple objects) and saves it to the database, if validations pass.
      # The resulting object is returned whether the object was saved successfully to the database or not.
      #
      # The +attributes+ parameter can be either be a Hash or an Array of Hashes.  These Hashes describe the
      # attributes on the objects that are to be created.
      #
      # ==== Examples
      #   # Create a single new object
      #   User.create(:first_name => 'Jamie')
      #
      #   # Create an Array of new objects
      #   User.create([{ :first_name => 'Jamie' }, { :first_name => 'Jeremy' }])
      #
      #   # Create a single object and pass it into a block to set other attributes.
      #   User.create(:first_name => 'Jamie') do |u|
      #     u.is_admin = false
      #   end
      #
      #   # Creating an Array of new objects using a block, where the block is executed for each object:
      #   User.create([{ :first_name => 'Jamie' }, { :first_name => 'Jeremy' }]) do |u|
      #     u.is_admin = false
      #   end
      def create(attributes = nil, &block)
        if attributes.is_a?(Array)
          attributes.collect { |attr| create(attr, &block) }
        else
          object = new(attributes)
          yield(object) if block_given?
          object.save
          object
        end
      end

      # Returns the result of an SQL statement that should only include a COUNT(*) in the SELECT part.
      # The use of this method should be restricted to complicated SQL queries that can't be executed
      # using the ActiveRecord::Calculations class methods.  Look into those before using this.
      #
      # ==== Parameters
      #
      # * +sql+ - An SQL statement which should return a count query from the database, see the example below.
      #
      # ==== Examples
      #
      #   Product.count_by_sql "SELECT COUNT(*) FROM sales s, customers c WHERE s.customer_id = c.id"
      def count_by_sql(sql)
        sql = sanitize_conditions(sql)
        connection.select_value(sql, "#{name} Count").to_i
      end

      # Resets one or more counter caches to their correct value using an SQL
      # count query.  This is useful when adding new counter caches, or if the
      # counter has been corrupted or modified directly by SQL.
      #
      # ==== Parameters
      #
      # * +id+ - The id of the object you wish to reset a counter on.
      # * +counters+ - One or more counter names to reset
      #
      # ==== Examples
      #
      #   # For Post with id #1 records reset the comments_count
      #   Post.reset_counters(1, :comments)
      def reset_counters(id, *counters)
        object = find(id)
        counters.each do |association|
          child_class = reflect_on_association(association).klass
          counter_name = child_class.reflect_on_association(self.name.downcase.to_sym).counter_cache_column

          connection.update("UPDATE #{quoted_table_name} SET #{connection.quote_column_name(counter_name)} = #{object.send(association).count} WHERE #{connection.quote_column_name(primary_key)} = #{quote_value(object.id)}", "#{name} UPDATE")
        end
      end

      # A generic "counter updater" implementation, intended primarily to be
      # used by increment_counter and decrement_counter, but which may also
      # be useful on its own. It simply does a direct SQL update for the record
      # with the given ID, altering the given hash of counters by the amount
      # given by the corresponding value:
      #
      # ==== Parameters
      #
      # * +id+ - The id of the object you wish to update a counter on or an Array of ids.
      # * +counters+ - An Array of Hashes containing the names of the fields
      #   to update as keys and the amount to update the field by as values.
      #
      # ==== Examples
      #
      #   # For the Post with id of 5, decrement the comment_count by 1, and
      #   # increment the action_count by 1
      #   Post.update_counters 5, :comment_count => -1, :action_count => 1
      #   # Executes the following SQL:
      #   # UPDATE posts
      #   #    SET comment_count = comment_count - 1,
      #   #        action_count = action_count + 1
      #   #  WHERE id = 5
      #
      #   # For the Posts with id of 10 and 15, increment the comment_count by 1
      #   Post.update_counters [10, 15], :comment_count => 1
      #   # Executes the following SQL:
      #   # UPDATE posts
      #   #    SET comment_count = comment_count + 1,
      #   #  WHERE id IN (10, 15)
      def update_counters(id, counters)
        updates = counters.inject([]) { |list, (counter_name, increment)|
          sign = increment < 0 ? "-" : "+"
          list << "#{connection.quote_column_name(counter_name)} = COALESCE(#{connection.quote_column_name(counter_name)}, 0) #{sign} #{increment.abs}"
        }.join(", ")

        if id.is_a?(Array)
          ids_list = id.map {|i| quote_value(i)}.join(', ')
          condition = "IN  (#{ids_list})"
        else
          condition = "= #{quote_value(id)}"
        end

        update_all(updates, "#{connection.quote_column_name(primary_key)} #{condition}")
      end

      # Increment a number field by one, usually representing a count.
      #
      # This is used for caching aggregate values, so that they don't need to be computed every time.
      # For example, a DiscussionBoard may cache post_count and comment_count otherwise every time the board is
      # shown it would have to run an SQL query to find how many posts and comments there are.
      #
      # ==== Parameters
      #
      # * +counter_name+ - The name of the field that should be incremented.
      # * +id+ - The id of the object that should be incremented.
      #
      # ==== Examples
      #
      #   # Increment the post_count column for the record with an id of 5
      #   DiscussionBoard.increment_counter(:post_count, 5)
      def increment_counter(counter_name, id)
        update_counters(id, counter_name => 1)
      end

      # Decrement a number field by one, usually representing a count.
      #
      # This works the same as increment_counter but reduces the column value by 1 instead of increasing it.
      #
      # ==== Parameters
      #
      # * +counter_name+ - The name of the field that should be decremented.
      # * +id+ - The id of the object that should be decremented.
      #
      # ==== Examples
      #
      #   # Decrement the post_count column for the record with an id of 5
      #   DiscussionBoard.decrement_counter(:post_count, 5)
      def decrement_counter(counter_name, id)
        update_counters(id, counter_name => -1)
      end

      # Attributes named in this macro are protected from mass-assignment,
      # such as <tt>new(attributes)</tt>,
      # <tt>update_attributes(attributes)</tt>, or
      # <tt>attributes=(attributes)</tt>.
      #
      # Mass-assignment to these attributes will simply be ignored, to assign
      # to them you can use direct writer methods. This is meant to protect
      # sensitive attributes from being overwritten by malicious users
      # tampering with URLs or forms.
      #
      #   class Customer < ActiveRecord::Base
      #     attr_protected :credit_rating
      #   end
      #
      #   customer = Customer.new("name" => David, "credit_rating" => "Excellent")
      #   customer.credit_rating # => nil
      #   customer.attributes = { "description" => "Jolly fellow", "credit_rating" => "Superb" }
      #   customer.credit_rating # => nil
      #
      #   customer.credit_rating = "Average"
      #   customer.credit_rating # => "Average"
      #
      # To start from an all-closed default and enable attributes as needed,
      # have a look at +attr_accessible+.
      #
      # If the access logic of your application is richer you can use <tt>Hash#except</tt>
      # or <tt>Hash#slice</tt> to sanitize the hash of parameters before they are
      # passed to Active Record.
      #
      # For example, it could be the case that the list of protected attributes
      # for a given model depends on the role of the user:
      #
      #   # Assumes plan_id is not protected because it depends on the role.
      #   params[:account] = params[:account].except(:plan_id) unless admin?
      #   @account.update_attributes(params[:account])
      #
      # Note that +attr_protected+ is still applied to the received hash. Thus,
      # with this technique you can at most _extend_ the list of protected
      # attributes for a particular mass-assignment call.
      def attr_protected(*attributes)
        write_inheritable_attribute(:attr_protected, Set.new(attributes.map {|a| a.to_s}) + (protected_attributes || []))
      end

      # Returns an array of all the attributes that have been protected from mass-assignment.
      def protected_attributes # :nodoc:
        read_inheritable_attribute(:attr_protected)
      end

      # Specifies a white list of model attributes that can be set via
      # mass-assignment, such as <tt>new(attributes)</tt>,
      # <tt>update_attributes(attributes)</tt>, or
      # <tt>attributes=(attributes)</tt>
      #
      # This is the opposite of the +attr_protected+ macro: Mass-assignment
      # will only set attributes in this list, to assign to the rest of
      # attributes you can use direct writer methods. This is meant to protect
      # sensitive attributes from being overwritten by malicious users
      # tampering with URLs or forms. If you'd rather start from an all-open
      # default and restrict attributes as needed, have a look at
      # +attr_protected+.
      #
      #   class Customer < ActiveRecord::Base
      #     attr_accessible :name, :nickname
      #   end
      #
      #   customer = Customer.new(:name => "David", :nickname => "Dave", :credit_rating => "Excellent")
      #   customer.credit_rating # => nil
      #   customer.attributes = { :name => "Jolly fellow", :credit_rating => "Superb" }
      #   customer.credit_rating # => nil
      #
      #   customer.credit_rating = "Average"
      #   customer.credit_rating # => "Average"
      #
      # If the access logic of your application is richer you can use <tt>Hash#except</tt>
      # or <tt>Hash#slice</tt> to sanitize the hash of parameters before they are
      # passed to Active Record.
      #
      # For example, it could be the case that the list of accessible attributes
      # for a given model depends on the role of the user:
      #
      #   # Assumes plan_id is accessible because it depends on the role.
      #   params[:account] = params[:account].except(:plan_id) unless admin?
      #   @account.update_attributes(params[:account])
      #
      # Note that +attr_accessible+ is still applied to the received hash. Thus,
      # with this technique you can at most _narrow_ the list of accessible
      # attributes for a particular mass-assignment call.
      def attr_accessible(*attributes)
        write_inheritable_attribute(:attr_accessible, Set.new(attributes.map(&:to_s)) + (accessible_attributes || []))
      end

      # Returns an array of all the attributes that have been made accessible to mass-assignment.
      def accessible_attributes # :nodoc:
        read_inheritable_attribute(:attr_accessible)
      end

       # Attributes listed as readonly can be set for a new record, but will be ignored in database updates afterwards.
       def attr_readonly(*attributes)
         write_inheritable_attribute(:attr_readonly, Set.new(attributes.map(&:to_s)) + (readonly_attributes || []))
       end

       # Returns an array of all the attributes that have been specified as readonly.
       def readonly_attributes
         read_inheritable_attribute(:attr_readonly) || []
       end

      # If you have an attribute that needs to be saved to the database as an object, and retrieved as the same object,
      # then specify the name of that attribute using this method and it will be handled automatically.
      # The serialization is done through YAML. If +class_name+ is specified, the serialized object must be of that
      # class on retrieval or SerializationTypeMismatch will be raised.
      #
      # ==== Parameters
      #
      # * +attr_name+ - The field name that should be serialized.
      # * +class_name+ - Optional, class name that the object type should be equal to.
      #
      # ==== Example
      #   # Serialize a preferences attribute
      #   class User
      #     serialize :preferences
      #   end
      def serialize(attr_name, class_name = Object)
        serialized_attributes[attr_name.to_s] = class_name
      end

      # Returns a hash of all the attributes that have been specified for serialization as keys and their class restriction as values.
      def serialized_attributes
        read_inheritable_attribute(:attr_serialized) or write_inheritable_attribute(:attr_serialized, {})
      end

      # Guesses the table name (in forced lower-case) based on the name of the class in the inheritance hierarchy descending
      # directly from ActiveRecord::Base. So if the hierarchy looks like: Reply < Message < ActiveRecord::Base, then Message is used
      # to guess the table name even when called on Reply. The rules used to do the guess are handled by the Inflector class
      # in Active Support, which knows almost all common English inflections. You can add new inflections in config/initializers/inflections.rb.
      #
      # Nested classes are given table names prefixed by the singular form of
      # the parent's table name. Enclosing modules are not considered.
      #
      # ==== Examples
      #
      #   class Invoice < ActiveRecord::Base; end;
      #   file                  class               table_name
      #   invoice.rb            Invoice             invoices
      #
      #   class Invoice < ActiveRecord::Base; class Lineitem < ActiveRecord::Base; end; end;
      #   file                  class               table_name
      #   invoice.rb            Invoice::Lineitem   invoice_lineitems
      #
      #   module Invoice; class Lineitem < ActiveRecord::Base; end; end;
      #   file                  class               table_name
      #   invoice/lineitem.rb   Invoice::Lineitem   lineitems
      #
      # Additionally, the class-level +table_name_prefix+ is prepended and the
      # +table_name_suffix+ is appended.  So if you have "myapp_" as a prefix,
      # the table name guess for an Invoice class becomes "myapp_invoices".
      # Invoice::Lineitem becomes "myapp_invoice_lineitems".
      #
      # You can also overwrite this class method to allow for unguessable
      # links, such as a Mouse class with a link to a "mice" table. Example:
      #
      #   class Mouse < ActiveRecord::Base
      #     set_table_name "mice"
      #   end
      def table_name
        reset_table_name
      end

      def quoted_table_name
        @quoted_table_name ||= connection.quote_table_name(table_name)
      end

      def reset_table_name #:nodoc:
        base = base_class

        name =
          # STI subclasses always use their superclass' table.
          unless self == base
            base.table_name
          else
            # Nested classes are prefixed with singular parent table name.
            if parent < ActiveRecord::Base && !parent.abstract_class?
              contained = parent.table_name
              contained = contained.singularize if parent.pluralize_table_names
              contained << '_'
            end
            name = "#{full_table_name_prefix}#{contained}#{undecorated_table_name(base.name)}#{table_name_suffix}"
          end

        @quoted_table_name = nil
        set_table_name(name)
        name
      end

      def full_table_name_prefix #:nodoc:
        (parents.detect{ |p| p.respond_to?(:table_name_prefix) } || self).table_name_prefix
      end

      # Defines the column name for use with single table inheritance
      # -- can be set in subclasses like so: self.inheritance_column = "type_id"
      def inheritance_column
        @inheritance_column ||= "type".freeze
      end

      # Lazy-set the sequence name to the connection's default.  This method
      # is only ever called once since set_sequence_name overrides it.
      def sequence_name #:nodoc:
        reset_sequence_name
      end

      def reset_sequence_name #:nodoc:
        default = connection.default_sequence_name(table_name, primary_key)
        set_sequence_name(default)
        default
      end

      # Sets the table name to use to the given value, or (if the value
      # is nil or false) to the value returned by the given block.
      #
      #   class Project < ActiveRecord::Base
      #     set_table_name "project"
      #   end
      def set_table_name(value = nil, &block)
        define_attr_method :table_name, value, &block
      end
      alias :table_name= :set_table_name

      # Sets the name of the inheritance column to use to the given value,
      # or (if the value # is nil or false) to the value returned by the
      # given block.
      #
      #   class Project < ActiveRecord::Base
      #     set_inheritance_column do
      #       original_inheritance_column + "_id"
      #     end
      #   end
      def set_inheritance_column(value = nil, &block)
        define_attr_method :inheritance_column, value, &block
      end
      alias :inheritance_column= :set_inheritance_column

      # Sets the name of the sequence to use when generating ids to the given
      # value, or (if the value is nil or false) to the value returned by the
      # given block. This is required for Oracle and is useful for any
      # database which relies on sequences for primary key generation.
      #
      # If a sequence name is not explicitly set when using Oracle or Firebird,
      # it will default to the commonly used pattern of: #{table_name}_seq
      #
      # If a sequence name is not explicitly set when using PostgreSQL, it
      # will discover the sequence corresponding to your primary key for you.
      #
      #   class Project < ActiveRecord::Base
      #     set_sequence_name "projectseq"   # default would have been "project_seq"
      #   end
      def set_sequence_name(value = nil, &block)
        define_attr_method :sequence_name, value, &block
      end
      alias :sequence_name= :set_sequence_name

      # Turns the +table_name+ back into a class name following the reverse rules of +table_name+.
      def class_name(table_name = table_name) # :nodoc:
        # remove any prefix and/or suffix from the table name
        class_name = table_name[table_name_prefix.length..-(table_name_suffix.length + 1)].camelize
        class_name = class_name.singularize if pluralize_table_names
        class_name
      end

      # Indicates whether the table associated with this class exists
      def table_exists?
        connection.table_exists?(table_name)
      end

      # Returns an array of column objects for the table associated with this class.
      def columns
        unless defined?(@columns) && @columns
          @columns = connection.columns(table_name, "#{name} Columns")
          @columns.each { |column| column.primary = column.name == primary_key }
        end
        @columns
      end

      # Returns a hash of column objects for the table associated with this class.
      def columns_hash
        @columns_hash ||= columns.inject({}) { |hash, column| hash[column.name] = column; hash }
      end

      # Returns an array of column names as strings.
      def column_names
        @column_names ||= columns.map { |column| column.name }
      end

      # Returns an array of column objects where the primary id, all columns ending in "_id" or "_count",
      # and columns used for single table inheritance have been removed.
      def content_columns
        @content_columns ||= columns.reject { |c| c.primary || c.name =~ /(_id|_count)$/ || c.name == inheritance_column }
      end

      # Returns a hash of all the methods added to query each of the columns in the table with the name of the method as the key
      # and true as the value. This makes it possible to do O(1) lookups in respond_to? to check if a given method for attribute
      # is available.
      def column_methods_hash #:nodoc:
        @dynamic_methods_hash ||= column_names.inject(Hash.new(false)) do |methods, attr|
          attr_name = attr.to_s
          methods[attr.to_sym]       = attr_name
          methods["#{attr}=".to_sym] = attr_name
          methods["#{attr}?".to_sym] = attr_name
          methods["#{attr}_before_type_cast".to_sym] = attr_name
          methods
        end
      end

      # Resets all the cached information about columns, which will cause them
      # to be reloaded on the next request.
      #
      # The most common usage pattern for this method is probably in a migration,
      # when just after creating a table you want to populate it with some default
      # values, eg:
      #
      #  class CreateJobLevels < ActiveRecord::Migration
      #    def self.up
      #      create_table :job_levels do |t|
      #        t.integer :id
      #        t.string :name
      #
      #        t.timestamps
      #      end
      #
      #      JobLevel.reset_column_information
      #      %w{assistant executive manager director}.each do |type|
      #        JobLevel.create(:name => type)
      #      end
      #    end
      #
      #    def self.down
      #      drop_table :job_levels
      #    end
      #  end
      def reset_column_information
        undefine_attribute_methods
        @column_names = @columns = @columns_hash = @content_columns = @dynamic_methods_hash = @inheritance_column = nil
        @arel_engine = @unscoped = @arel_table = nil
      end

      def reset_column_information_and_inheritable_attributes_for_all_subclasses#:nodoc:
        subclasses.each { |klass| klass.reset_inheritable_attributes; klass.reset_column_information }
      end

      # Set the lookup ancestors for ActiveModel.
      def lookup_ancestors #:nodoc:
        klass = self
        classes = [klass]
        while klass != klass.base_class
          classes << klass = klass.superclass
        end
        classes
      rescue
        # OPTIMIZE this rescue is to fix this test: ./test/cases/reflection_test.rb:56:in `test_human_name_for_column'
        # Apparently the method base_class causes some trouble.
        # It now works for sure.
        [self]
      end

      # Set the i18n scope to overwrite ActiveModel.
      def i18n_scope #:nodoc:
        :activerecord
      end

      # True if this isn't a concrete subclass needing a STI type condition.
      def descends_from_active_record?
        if superclass.abstract_class?
          superclass.descends_from_active_record?
        else
          superclass == Base || !columns_hash.include?(inheritance_column)
        end
      end

      def finder_needs_type_condition? #:nodoc:
        # This is like this because benchmarking justifies the strange :false stuff
        :true == (@finder_needs_type_condition ||= descends_from_active_record? ? :false : :true)
      end

      # Returns a string like 'Post id:integer, title:string, body:text'
      def inspect
        if self == Base
          super
        elsif abstract_class?
          "#{super}(abstract)"
        elsif table_exists?
          attr_list = columns.map { |c| "#{c.name}: #{c.type}" } * ', '
          "#{super}(#{attr_list})"
        else
          "#{super}(Table doesn't exist)"
        end
      end

      def quote_value(value, column = nil) #:nodoc:
        connection.quote(value,column)
      end

      # Used to sanitize objects before they're used in an SQL SELECT statement. Delegates to <tt>connection.quote</tt>.
      def sanitize(object) #:nodoc:
        connection.quote(object)
      end

      # Overwrite the default class equality method to provide support for association proxies.
      def ===(object)
        object.is_a?(self)
      end

      # Returns the base AR subclass that this class descends from. If A
      # extends AR::Base, A.base_class will return A. If B descends from A
      # through some arbitrarily deep hierarchy, B.base_class will return A.
      def base_class
        class_of_active_record_descendant(self)
      end

      # Set this to true if this is an abstract class (see <tt>abstract_class?</tt>).
      attr_accessor :abstract_class

      # Returns whether this class is a base AR class.  If A is a base class and
      # B descends from A, then B.base_class will return B.
      def abstract_class?
        defined?(@abstract_class) && @abstract_class == true
      end

      def respond_to?(method_id, include_private = false)
        if match = DynamicFinderMatch.match(method_id)
          return true if all_attributes_exists?(match.attribute_names)
        elsif match = DynamicScopeMatch.match(method_id)
          return true if all_attributes_exists?(match.attribute_names)
        end

        super
      end

      def sti_name
        store_full_sti_class ? name : name.demodulize
      end

      def unscoped
        @unscoped ||= Relation.new(self, arel_table)
        finder_needs_type_condition? ? @unscoped.where(type_condition) : @unscoped
      end

      def arel_table
        @arel_table ||= Arel::Table.new(table_name, :engine => arel_engine)
      end

      def arel_engine
        @arel_engine ||= begin
          if self == ActiveRecord::Base
            Arel::Table.engine
          else
            connection_handler.connection_pools[name] ? Arel::Sql::Engine.new(self) : superclass.arel_engine
          end
        end
      end

      private
        # Finder methods must instantiate through this method to work with the
        # single-table inheritance model that makes it possible to create
        # objects of different types from the same table.
        def instantiate(record)
          object = find_sti_class(record[inheritance_column]).allocate

          object.instance_variable_set(:'@attributes', record)
          object.instance_variable_set(:'@attributes_cache', {})
          object.instance_variable_set(:@new_record, false)
          object.instance_variable_set(:@readonly, false)
          object.instance_variable_set(:@destroyed, false)
          object.instance_variable_set(:@marked_for_destruction, false)
          object.instance_variable_set(:@previously_changed, {})
          object.instance_variable_set(:@changed_attributes, {})

          object.send(:_run_find_callbacks)
          object.send(:_run_initialize_callbacks)

          object
        end

        def find_sti_class(type_name)
          if type_name.blank? || !columns_hash.include?(inheritance_column)
            self
          else
            begin
              compute_type(type_name)
            rescue NameError
              raise SubclassNotFound,
                "The single-table inheritance mechanism failed to locate the subclass: '#{type_name}'. " +
                "This error is raised because the column '#{inheritance_column}' is reserved for storing the class in case of inheritance. " +
                "Please rename this column if you didn't intend it to be used for storing the inheritance class " +
                "or overwrite #{name}.inheritance_column to use another column for that information."
            end
          end
        end

        # Nest the type name in the same module as this class.
        # Bar is "MyApp::Business::Bar" relative to MyApp::Business::Foo
        def type_name_with_module(type_name)
          if store_full_sti_class
            type_name
          else
            (/^::/ =~ type_name) ? type_name : "#{parent.name}::#{type_name}"
          end
        end

        def construct_finder_arel(options = {}, scope = nil)
          relation = options.is_a?(Hash) ? unscoped.apply_finder_options(options) : unscoped.merge(options)
          relation = scope.merge(relation) if scope
          relation
        end

        def type_condition
          sti_column = arel_table[inheritance_column]
          condition = sti_column.eq(sti_name)
          subclasses.each{|subclass| condition = condition.or(sti_column.eq(subclass.sti_name)) }

          condition
        end

        # Guesses the table name, but does not decorate it with prefix and suffix information.
        def undecorated_table_name(class_name = base_class.name)
          table_name = class_name.to_s.demodulize.underscore
          table_name = table_name.pluralize if pluralize_table_names
          table_name
        end

        # Enables dynamic finders like <tt>find_by_user_name(user_name)</tt> and <tt>find_by_user_name_and_password(user_name, password)</tt>
        # that are turned into <tt>where(:user_name => user_name).first</tt> and <tt>where(:user_name => user_name, :password => :password).first</tt>
        # respectively. Also works for <tt>all</tt> by using <tt>find_all_by_amount(50)</tt> that is turned into <tt>where(:amount => 50).all</tt>.
        #
        # It's even possible to use all the additional parameters to +find+. For example, the full interface for +find_all_by_amount+
        # is actually <tt>find_all_by_amount(amount, options)</tt>.
        #
        # Each dynamic finder, scope or initializer/creator is also defined in the class after it is first invoked, so that future
        # attempts to use it do not run through method_missing.
        def method_missing(method_id, *arguments, &block)
          if match = DynamicFinderMatch.match(method_id)
            attribute_names = match.attribute_names
            super unless all_attributes_exists?(attribute_names)
            if match.finder?
              options = arguments.extract_options!
              relation = options.any? ? construct_finder_arel(options, current_scoped_methods) : scoped
              relation.send :find_by_attributes, match, attribute_names, *arguments
            elsif match.instantiator?
              scoped.send :find_or_instantiator_by_attributes, match, attribute_names, *arguments, &block
            end
          elsif match = DynamicScopeMatch.match(method_id)
            attribute_names = match.attribute_names
            super unless all_attributes_exists?(attribute_names)
            if match.scope?
              self.class_eval %{
                def self.#{method_id}(*args)                        # def self.scoped_by_user_name_and_password(*args)
                  options = args.extract_options!                   #   options = args.extract_options!
                  attributes = construct_attributes_from_arguments( #   attributes = construct_attributes_from_arguments(
                    [:#{attribute_names.join(',:')}], args          #     [:user_name, :password], args
                  )                                                 #   )
                                                                    #
                  scoped(:conditions => attributes)                 #   scoped(:conditions => attributes)
                end                                                 # end
              }, __FILE__, __LINE__
              send(method_id, *arguments)
            end
          else
            super
          end
        end

        def construct_attributes_from_arguments(attribute_names, arguments)
          attributes = {}
          attribute_names.each_with_index { |name, idx| attributes[name] = arguments[idx] }
          attributes
        end

        # Similar in purpose to +expand_hash_conditions_for_aggregates+.
        def expand_attribute_names_for_aggregates(attribute_names)
          expanded_attribute_names = []
          attribute_names.each do |attribute_name|
            unless (aggregation = reflect_on_aggregation(attribute_name.to_sym)).nil?
              aggregate_mapping(aggregation).each do |field_attr, aggregate_attr|
                expanded_attribute_names << field_attr
              end
            else
              expanded_attribute_names << attribute_name
            end
          end
          expanded_attribute_names
        end

        def all_attributes_exists?(attribute_names)
          attribute_names = expand_attribute_names_for_aggregates(attribute_names)
          attribute_names.all? { |name| column_methods_hash.include?(name.to_sym) }
        end

        def attribute_condition(quoted_column_name, argument)
          case argument
            when nil   then "#{quoted_column_name} IS ?"
            when Array, ActiveRecord::Associations::AssociationCollection, ActiveRecord::NamedScope::Scope then "#{quoted_column_name} IN (?)"
            when Range then if argument.exclude_end?
                              "#{quoted_column_name} >= ? AND #{quoted_column_name} < ?"
                            else
                              "#{quoted_column_name} BETWEEN ? AND ?"
                            end
            else            "#{quoted_column_name} = ?"
          end
        end

      protected
        # Scope parameters to method calls within the block.  Takes a hash of method_name => parameters hash.
        # method_name may be <tt>:find</tt> or <tt>:create</tt>. <tt>:find</tt> parameter is <tt>Relation</tt> while
        # <tt>:create</tt> parameters are an attributes hash.
        #
        #   class Article < ActiveRecord::Base
        #     def self.create_with_scope
        #       with_scope(:find => where(:blog_id => 1), :create => { :blog_id => 1 }) do
        #         find(1) # => SELECT * from articles WHERE blog_id = 1 AND id = 1
        #         a = create(1)
        #         a.blog_id # => 1
        #       end
        #     end
        #   end
        #
        # In nested scopings, all previous parameters are overwritten by the innermost rule, with the exception of
        # <tt>where</tt>, <tt>includes</tt>, and <tt>joins</tt> operations in <tt>Relation</tt>, which are merged.
        #
        # <tt>joins</tt> operations are uniqued so multiple scopes can join in the same table without table aliasing
        # problems.  If you need to join multiple tables, but still want one of the tables to be uniqued, use the
        # array of strings format for your joins.
        #
        #   class Article < ActiveRecord::Base
        #     def self.find_with_scope
        #       with_scope(:find => where(:blog_id => 1).limit(1), :create => { :blog_id => 1 }) do
        #         with_scope(:find => limit(10)) do
        #           all # => SELECT * from articles WHERE blog_id = 1 LIMIT 10
        #         end
        #         with_scope(:find => where(:author_id => 3)) do
        #           all # => SELECT * from articles WHERE blog_id = 1 AND author_id = 3 LIMIT 1
        #         end
        #       end
        #     end
        #   end
        #
        # You can ignore any previous scopings by using the <tt>with_exclusive_scope</tt> method.
        #
        #   class Article < ActiveRecord::Base
        #     def self.find_with_exclusive_scope
        #       with_scope(:find => where(:blog_id => 1).limit(1)) do
        #         with_exclusive_scope(:find => limit(10))
        #           all # => SELECT * from articles LIMIT 10
        #         end
        #       end
        #     end
        #   end
        #
        # *Note*: the +:find+ scope also has effect on update and deletion methods,
        # like +update_all+ and +delete_all+.
        def with_scope(method_scoping = {}, action = :merge, &block)
          method_scoping = method_scoping.method_scoping if method_scoping.respond_to?(:method_scoping)

          if method_scoping.is_a?(Hash)
            # Dup first and second level of hash (method and params).
            method_scoping = method_scoping.inject({}) do |hash, (method, params)|
              hash[method] = (params == true) ? params : params.dup
              hash
            end

            method_scoping.assert_valid_keys([ :find, :create ])
            relation = construct_finder_arel(method_scoping[:find] || {})

            if current_scoped_methods && current_scoped_methods.create_with_value && method_scoping[:create]
              scope_for_create = if action == :merge
                current_scoped_methods.create_with_value.merge(method_scoping[:create])
              else
                method_scoping[:create]
              end

              relation = relation.create_with(scope_for_create)
            else
              scope_for_create = method_scoping[:create]
              scope_for_create ||= current_scoped_methods.create_with_value if current_scoped_methods
              relation = relation.create_with(scope_for_create) if scope_for_create
            end

            method_scoping = relation
          end

          method_scoping = current_scoped_methods.merge(method_scoping) if current_scoped_methods && action ==  :merge

          self.scoped_methods << method_scoping
          begin
            yield
          ensure
            self.scoped_methods.pop
          end
        end

        # Works like with_scope, but discards any nested properties.
        def with_exclusive_scope(method_scoping = {}, &block)
          with_scope(method_scoping, :overwrite, &block)
        end

        def subclasses #:nodoc:
          @@subclasses[self] ||= []
          @@subclasses[self] + extra = @@subclasses[self].inject([]) {|list, subclass| list + subclass.subclasses }
        end

        # Sets the default options for the model. The format of the
        # <tt>options</tt> argument is the same as in find.
        #
        #   class Person < ActiveRecord::Base
        #     default_scope order('last_name, first_name')
        #   end
        def default_scope(options = {})
          self.default_scoping << construct_finder_arel(options)
        end

        def scoped_methods #:nodoc:
          key = :"#{self}_scoped_methods"
          Thread.current[key] = Thread.current[key].presence || self.default_scoping.dup
        end

        def current_scoped_methods #:nodoc:
          scoped_methods.last
        end

        # Returns the class type of the record using the current module as a prefix. So descendants of
        # MyApp::Business::Account would appear as MyApp::Business::AccountSubclass.
        def compute_type(type_name)
          modularized_name = type_name_with_module(type_name)
          silence_warnings do
            begin
              class_eval(modularized_name, __FILE__, __LINE__)
            rescue NameError
              class_eval(type_name, __FILE__, __LINE__)
            end
          end
        end

        # Returns the class descending directly from ActiveRecord::Base or an
        # abstract class, if any, in the inheritance hierarchy.
        def class_of_active_record_descendant(klass)
          if klass.superclass == Base || klass.superclass.abstract_class?
            klass
          elsif klass.superclass.nil?
            raise ActiveRecordError, "#{name} doesn't belong in a hierarchy descending from ActiveRecord"
          else
            class_of_active_record_descendant(klass.superclass)
          end
        end

        # Returns the name of the class descending directly from Active Record in the inheritance hierarchy.
        def class_name_of_active_record_descendant(klass) #:nodoc:
          klass.base_class.name
        end

        # Accepts an array, hash, or string of SQL conditions and sanitizes
        # them into a valid SQL fragment for a WHERE clause.
        #   ["name='%s' and group_id='%s'", "foo'bar", 4]  returns  "name='foo''bar' and group_id='4'"
        #   { :name => "foo'bar", :group_id => 4 }  returns "name='foo''bar' and group_id='4'"
        #   "name='foo''bar' and group_id='4'" returns "name='foo''bar' and group_id='4'"
        def sanitize_sql_for_conditions(condition, table_name = self.table_name)
          return nil if condition.blank?

          case condition
            when Array; sanitize_sql_array(condition)
            when Hash;  sanitize_sql_hash_for_conditions(condition, table_name)
            else        condition
          end
        end
        alias_method :sanitize_sql, :sanitize_sql_for_conditions

        # Accepts an array, hash, or string of SQL conditions and sanitizes
        # them into a valid SQL fragment for a SET clause.
        #   { :name => nil, :group_id => 4 }  returns "name = NULL , group_id='4'"
        def sanitize_sql_for_assignment(assignments)
          case assignments
            when Array; sanitize_sql_array(assignments)
            when Hash;  sanitize_sql_hash_for_assignment(assignments)
            else        assignments
          end
        end

        def aggregate_mapping(reflection)
          mapping = reflection.options[:mapping] || [reflection.name, reflection.name]
          mapping.first.is_a?(Array) ? mapping : [mapping]
        end

        # Accepts a hash of SQL conditions and replaces those attributes
        # that correspond to a +composed_of+ relationship with their expanded
        # aggregate attribute values.
        # Given:
        #     class Person < ActiveRecord::Base
        #       composed_of :address, :class_name => "Address",
        #         :mapping => [%w(address_street street), %w(address_city city)]
        #     end
        # Then:
        #     { :address => Address.new("813 abc st.", "chicago") }
        #       # => { :address_street => "813 abc st.", :address_city => "chicago" }
        def expand_hash_conditions_for_aggregates(attrs)
          expanded_attrs = {}
          attrs.each do |attr, value|
            unless (aggregation = reflect_on_aggregation(attr.to_sym)).nil?
              mapping = aggregate_mapping(aggregation)
              mapping.each do |field_attr, aggregate_attr|
                if mapping.size == 1 && !value.respond_to?(aggregate_attr)
                  expanded_attrs[field_attr] = value
                else
                  expanded_attrs[field_attr] = value.send(aggregate_attr)
                end
              end
            else
              expanded_attrs[attr] = value
            end
          end
          expanded_attrs
        end

        # Sanitizes a hash of attribute/value pairs into SQL conditions for a WHERE clause.
        #   { :name => "foo'bar", :group_id => 4 }
        #     # => "name='foo''bar' and group_id= 4"
        #   { :status => nil, :group_id => [1,2,3] }
        #     # => "status IS NULL and group_id IN (1,2,3)"
        #   { :age => 13..18 }
        #     # => "age BETWEEN 13 AND 18"
        #   { 'other_records.id' => 7 }
        #     # => "`other_records`.`id` = 7"
        #   { :other_records => { :id => 7 } }
        #     # => "`other_records`.`id` = 7"
        # And for value objects on a composed_of relationship:
        #   { :address => Address.new("123 abc st.", "chicago") }
        #     # => "address_street='123 abc st.' and address_city='chicago'"
        def sanitize_sql_hash_for_conditions(attrs, default_table_name = self.table_name)
          attrs = expand_hash_conditions_for_aggregates(attrs)

          table = Arel::Table.new(self.table_name, :engine => arel_engine, :as => default_table_name)
          builder = PredicateBuilder.new(arel_engine)
          builder.build_from_hash(attrs, table).map(&:to_sql).join(' AND ')
        end
        alias_method :sanitize_sql_hash, :sanitize_sql_hash_for_conditions

        # Sanitizes a hash of attribute/value pairs into SQL conditions for a SET clause.
        #   { :status => nil, :group_id => 1 }
        #     # => "status = NULL , group_id = 1"
        def sanitize_sql_hash_for_assignment(attrs)
          attrs.map do |attr, value|
            "#{connection.quote_column_name(attr)} = #{quote_bound_value(value)}"
          end.join(', ')
        end

        # Accepts an array of conditions.  The array has each value
        # sanitized and interpolated into the SQL statement.
        #   ["name='%s' and group_id='%s'", "foo'bar", 4]  returns  "name='foo''bar' and group_id='4'"
        def sanitize_sql_array(ary)
          statement, *values = ary
          if values.first.is_a?(Hash) and statement =~ /:\w+/
            replace_named_bind_variables(statement, values.first)
          elsif statement.include?('?')
            replace_bind_variables(statement, values)
          else
            statement % values.collect { |value| connection.quote_string(value.to_s) }
          end
        end

        alias_method :sanitize_conditions, :sanitize_sql

        def replace_bind_variables(statement, values) #:nodoc:
          raise_if_bind_arity_mismatch(statement, statement.count('?'), values.size)
          bound = values.dup
          statement.gsub('?') { quote_bound_value(bound.shift) }
        end

        def replace_named_bind_variables(statement, bind_vars) #:nodoc:
          statement.gsub(/(:?):([a-zA-Z]\w*)/) do
            if $1 == ':' # skip postgresql casts
              $& # return the whole match
            elsif bind_vars.include?(match = $2.to_sym)
              quote_bound_value(bind_vars[match])
            else
              raise PreparedStatementInvalid, "missing value for :#{match} in #{statement}"
            end
          end
        end

        def expand_range_bind_variables(bind_vars) #:nodoc:
          expanded = []

          bind_vars.each do |var|
            next if var.is_a?(Hash)

            if var.is_a?(Range)
              expanded << var.first
              expanded << var.last
            else
              expanded << var
            end
          end

          expanded
        end

        def quote_bound_value(value) #:nodoc:
          if value.respond_to?(:map) && !value.acts_like?(:string)
            if value.respond_to?(:empty?) && value.empty?
              connection.quote(nil)
            else
              value.map { |v| connection.quote(v) }.join(',')
            end
          else
            connection.quote(value)
          end
        end

        def raise_if_bind_arity_mismatch(statement, expected, provided) #:nodoc:
          unless expected == provided
            raise PreparedStatementInvalid, "wrong number of bind variables (#{provided} for #{expected}) in: #{statement}"
          end
        end

        def encode_quoted_value(value) #:nodoc:
          quoted_value = connection.quote(value)
          quoted_value = "'#{quoted_value[1..-2].gsub(/\'/, "\\\\'")}'" if quoted_value.include?("\\\'") # (for ruby mode) "
          quoted_value
        end
    end

    public
      # New objects can be instantiated as either empty (pass no construction parameter) or pre-set with
      # attributes but not yet saved (pass a hash with key names matching the associated table column names).
      # In both instances, valid attribute keys are determined by the column names of the associated table --
      # hence you can't have attributes that aren't part of the table columns.
      def initialize(attributes = nil)
        @attributes = attributes_from_column_definition
        @attributes_cache = {}
        @new_record = true
        @readonly = false
        @destroyed = false
        @marked_for_destruction = false
        @previously_changed = {}
        @changed_attributes = {}

        ensure_proper_type

        if scope = self.class.send(:current_scoped_methods)
          create_with = scope.scope_for_create
          create_with.each { |att,value| self.send("#{att}=", value) } if create_with
        end
        self.attributes = attributes unless attributes.nil?

        result = yield self if block_given?
        _run_initialize_callbacks
        result
      end

      # Cloned objects have no id assigned and are treated as new records. Note that this is a "shallow" clone
      # as it copies the object's attributes only, not its associations. The extent of a "deep" clone is
      # application specific and is therefore left to the application to implement according to its need.
      def initialize_copy(other)
        # Think the assertion which fails if the after_initialize callback goes at the end of the method is wrong. The
        # deleted clone method called new which therefore called the after_initialize callback. It then went on to copy
        # over the attributes. But if it's copying the attributes afterwards then it hasn't finished initializing right?
        # For example in the test suite the topic model's after_initialize method sets the author_email_address to
        # test@test.com. I would have thought this would mean that all cloned models would have an author email address
        # of test@test.com. However the test_clone test method seems to test that this is not the case. As a result the
        # after_initialize callback has to be run *before* the copying of the atrributes rather than afterwards in order
        # for all tests to pass. This makes no sense to me.
        callback(:after_initialize) if respond_to_without_attributes?(:after_initialize)
        cloned_attributes = other.clone_attributes(:read_attribute_before_type_cast)
        cloned_attributes.delete(self.class.primary_key)
        @attributes = cloned_attributes
        clear_aggregation_cache
        @attributes_cache = {}
        @new_record = true
        ensure_proper_type

        if scope = self.class.send(:current_scoped_methods)
          create_with = scope.scope_for_create
          create_with.each { |att,value| self.send("#{att}=", value) } if create_with
        end
      end

      # Returns a String, which Action Pack uses for constructing an URL to this
      # object. The default implementation returns this record's id as a String,
      # or nil if this record's unsaved.
      #
      # For example, suppose that you have a User model, and that you have a
      # <tt>resources :users</tt> route. Normally, +user_path+ will
      # construct a path with the user object's 'id' in it:
      #
      #   user = User.find_by_name('Phusion')
      #   user_path(user)  # => "/users/1"
      #
      # You can override +to_param+ in your model to make +user_path+ construct
      # a path using the user's name instead of the user's id:
      #
      #   class User < ActiveRecord::Base
      #     def to_param  # overridden
      #       name
      #     end
      #   end
      #
      #   user = User.find_by_name('Phusion')
      #   user_path(user)  # => "/users/Phusion"
      def to_param
        # We can't use alias_method here, because method 'id' optimizes itself on the fly.
        id && id.to_s # Be sure to stringify the id for routes
      end

      # Returns a cache key that can be used to identify this record.
      #
      # ==== Examples
      #
      #   Product.new.cache_key     # => "products/new"
      #   Product.find(5).cache_key # => "products/5" (updated_at not available)
      #   Person.find(5).cache_key  # => "people/5-20071224150000" (updated_at available)
      def cache_key
        case
        when new_record?
          "#{self.class.model_name.cache_key}/new"
        when timestamp = self[:updated_at]
          "#{self.class.model_name.cache_key}/#{id}-#{timestamp.to_s(:number)}"
        else
          "#{self.class.model_name.cache_key}/#{id}"
        end
      end

      def quoted_id #:nodoc:
        quote_value(id, column_for_attribute(self.class.primary_key))
      end

      # Returns true if this object hasn't been saved yet -- that is, a record for the object doesn't exist yet; otherwise, returns false.
      def new_record?
        @new_record
      end

      # Returns true if this object has been destroyed, otherwise returns false.
      def destroyed?
        @destroyed
      end

      # Returns if the record is persisted, i.e. it's not a new record and it was not destroyed.
      def persisted?
        !(new_record? || destroyed?)
      end

      # :call-seq:
      #   save(options)
      #
      # Saves the model.
      #
      # If the model is new a record gets created in the database, otherwise
      # the existing record gets updated.
      #
      # By default, save always run validations. If any of them fail the action
      # is cancelled and +save+ returns +false+. However, if you supply
      # :validate => false, validations are bypassed altogether. See
      # ActiveRecord::Validations for more information.
      #
      # There's a series of callbacks associated with +save+. If any of the
      # <tt>before_*</tt> callbacks return +false+ the action is cancelled and
      # +save+ returns +false+. See ActiveRecord::Callbacks for further
      # details.
      def save
        create_or_update
      end

      # Saves the model.
      #
      # If the model is new a record gets created in the database, otherwise
      # the existing record gets updated.
      #
      # With <tt>save!</tt> validations always run. If any of them fail
      # ActiveRecord::RecordInvalid gets raised. See ActiveRecord::Validations
      # for more information.
      #
      # There's a series of callbacks associated with <tt>save!</tt>. If any of
      # the <tt>before_*</tt> callbacks return +false+ the action is cancelled
      # and <tt>save!</tt> raises ActiveRecord::RecordNotSaved. See
      # ActiveRecord::Callbacks for further details.
      def save!
        create_or_update || raise(RecordNotSaved)
      end

      # Deletes the record in the database and freezes this instance to
      # reflect that no changes should be made (since they can't be
      # persisted). Returns the frozen instance.
      #
      # The row is simply removed with a SQL +DELETE+ statement on the
      # record's primary key, and no callbacks are executed.
      #
      # To enforce the object's +before_destroy+ and +after_destroy+
      # callbacks, Observer methods, or any <tt>:dependent</tt> association
      # options, use <tt>#destroy</tt>.
      def delete
        self.class.delete(id) if persisted?
        @destroyed = true
        freeze
      end

      # Deletes the record in the database and freezes this instance to reflect that no changes should
      # be made (since they can't be persisted).
      def destroy
        if persisted?
          self.class.unscoped.where(self.class.arel_table[self.class.primary_key].eq(id)).delete_all
        end

        @destroyed = true
        freeze
      end

      # Returns an instance of the specified +klass+ with the attributes of the current record. This is mostly useful in relation to
      # single-table inheritance structures where you want a subclass to appear as the superclass. This can be used along with record
      # identification in Action Pack to allow, say, <tt>Client < Company</tt> to do something like render <tt>:partial => @client.becomes(Company)</tt>
      # to render that instance using the companies/company partial instead of clients/client.
      #
      # Note: The new instance will share a link to the same attributes as the original class. So any change to the attributes in either
      # instance will affect the other.
      def becomes(klass)
        became = klass.new
        became.instance_variable_set("@attributes", @attributes)
        became.instance_variable_set("@attributes_cache", @attributes_cache)
        became.instance_variable_set("@new_record", new_record?)
        became.instance_variable_set("@destroyed", destroyed?)
        became
      end

      # Updates a single attribute and saves the record without going through the normal validation procedure.
      # This is especially useful for boolean flags on existing records. The regular +update_attribute+ method
      # in Base is replaced with this when the validations module is mixed in, which it is by default.
      def update_attribute(name, value)
        send("#{name}=", value)
        save(:validate => false)
      end

      # Updates all the attributes from the passed-in Hash and saves the record. If the object is invalid, the saving will
      # fail and false will be returned.
      def update_attributes(attributes)
        self.attributes = attributes
        save
      end

      # Updates an object just like Base.update_attributes but calls save! instead of save so an exception is raised if the record is invalid.
      def update_attributes!(attributes)
        self.attributes = attributes
        save!
      end

      # Initializes +attribute+ to zero if +nil+ and adds the value passed as +by+ (default is 1).
      # The increment is performed directly on the underlying attribute, no setter is invoked.
      # Only makes sense for number-based attributes. Returns +self+.
      def increment(attribute, by = 1)
        self[attribute] ||= 0
        self[attribute] += by
        self
      end

      # Wrapper around +increment+ that saves the record. This method differs from
      # its non-bang version in that it passes through the attribute setter.
      # Saving is not subjected to validation checks. Returns +true+ if the
      # record could be saved.
      def increment!(attribute, by = 1)
        increment(attribute, by).update_attribute(attribute, self[attribute])
      end

      # Initializes +attribute+ to zero if +nil+ and subtracts the value passed as +by+ (default is 1).
      # The decrement is performed directly on the underlying attribute, no setter is invoked.
      # Only makes sense for number-based attributes. Returns +self+.
      def decrement(attribute, by = 1)
        self[attribute] ||= 0
        self[attribute] -= by
        self
      end

      # Wrapper around +decrement+ that saves the record. This method differs from
      # its non-bang version in that it passes through the attribute setter.
      # Saving is not subjected to validation checks. Returns +true+ if the
      # record could be saved.
      def decrement!(attribute, by = 1)
        decrement(attribute, by).update_attribute(attribute, self[attribute])
      end

      # Assigns to +attribute+ the boolean opposite of <tt>attribute?</tt>. So
      # if the predicate returns +true+ the attribute will become +false+. This
      # method toggles directly the underlying value without calling any setter.
      # Returns +self+.
      def toggle(attribute)
        self[attribute] = !send("#{attribute}?")
        self
      end

      # Wrapper around +toggle+ that saves the record. This method differs from
      # its non-bang version in that it passes through the attribute setter.
      # Saving is not subjected to validation checks. Returns +true+ if the
      # record could be saved.
      def toggle!(attribute)
        toggle(attribute).update_attribute(attribute, self[attribute])
      end

      # Reloads the attributes of this object from the database.
      # The optional options argument is passed to find when reloading so you
      # may do e.g. record.reload(:lock => true) to reload the same record with
      # an exclusive row lock.
      def reload(options = nil)
        clear_aggregation_cache
        clear_association_cache
        @attributes.update(self.class.send(:with_exclusive_scope) { self.class.find(self.id, options) }.instance_variable_get('@attributes'))
        @attributes_cache = {}
        self
      end

      # Returns true if the given attribute is in the attributes hash
      def has_attribute?(attr_name)
        @attributes.has_key?(attr_name.to_s)
      end

      # Returns an array of names for the attributes available on this object sorted alphabetically.
      def attribute_names
        @attributes.keys.sort
      end

      # Returns the value of the attribute identified by <tt>attr_name</tt> after it has been typecast (for example,
      # "2004-12-12" in a data column is cast to a date object, like Date.new(2004, 12, 12)).
      # (Alias for the protected read_attribute method).
      def [](attr_name)
        read_attribute(attr_name)
      end

      # Updates the attribute identified by <tt>attr_name</tt> with the specified +value+.
      # (Alias for the protected write_attribute method).
      def []=(attr_name, value)
        write_attribute(attr_name, value)
      end

      # Allows you to set all the attributes at once by passing in a hash with keys
      # matching the attribute names (which again matches the column names).
      #
      # If +guard_protected_attributes+ is true (the default), then sensitive
      # attributes can be protected from this form of mass-assignment by using
      # the +attr_protected+ macro. Or you can alternatively specify which
      # attributes *can* be accessed with the +attr_accessible+ macro. Then all the
      # attributes not included in that won't be allowed to be mass-assigned.
      #
      #   class User < ActiveRecord::Base
      #     attr_protected :is_admin
      #   end
      #
      #   user = User.new
      #   user.attributes = { :username => 'Phusion', :is_admin => true }
      #   user.username   # => "Phusion"
      #   user.is_admin?  # => false
      #
      #   user.send(:attributes=, { :username => 'Phusion', :is_admin => true }, false)
      #   user.is_admin?  # => true
      def attributes=(new_attributes, guard_protected_attributes = true)
        return if new_attributes.nil?
        attributes = new_attributes.dup
        attributes.stringify_keys!

        multi_parameter_attributes = []
        attributes = remove_attributes_protected_from_mass_assignment(attributes) if guard_protected_attributes

        attributes.each do |k, v|
          if k.include?("(")
            multi_parameter_attributes << [ k, v ]
          else
            respond_to?(:"#{k}=") ? send(:"#{k}=", v) : raise(UnknownAttributeError, "unknown attribute: #{k}")
          end
        end

        assign_multiparameter_attributes(multi_parameter_attributes)
      end

      # Returns a hash of all the attributes with their names as keys and the values of the attributes as values.
      def attributes
        attrs = {}
        attribute_names.each { |name| attrs[name] = read_attribute(name) }
        attrs
      end

      # Returns an <tt>#inspect</tt>-like string for the value of the
      # attribute +attr_name+. String attributes are elided after 50
      # characters, and Date and Time attributes are returned in the
      # <tt>:db</tt> format. Other attributes return the value of
      # <tt>#inspect</tt> without modification.
      #
      #   person = Person.create!(:name => "David Heinemeier Hansson " * 3)
      #
      #   person.attribute_for_inspect(:name)
      #   # => '"David Heinemeier Hansson David Heinemeier Hansson D..."'
      #
      #   person.attribute_for_inspect(:created_at)
      #   # => '"2009-01-12 04:48:57"'
      def attribute_for_inspect(attr_name)
        value = read_attribute(attr_name)

        if value.is_a?(String) && value.length > 50
          "#{value[0..50]}...".inspect
        elsif value.is_a?(Date) || value.is_a?(Time)
          %("#{value.to_s(:db)}")
        else
          value.inspect
        end
      end

      # Returns true if the specified +attribute+ has been set by the user or by a database load and is neither
      # nil nor empty? (the latter only applies to objects that respond to empty?, most notably Strings).
      def attribute_present?(attribute)
        value = read_attribute(attribute)
        !value.blank?
      end

      # Returns the column object for the named attribute.
      def column_for_attribute(name)
        self.class.columns_hash[name.to_s]
      end

      # Returns true if the +comparison_object+ is the same object, or is of the same type and has the same id.
      def ==(comparison_object)
        comparison_object.equal?(self) ||
          (comparison_object.instance_of?(self.class) &&
            comparison_object.id == id && !comparison_object.new_record?)
      end

      # Delegates to ==
      def eql?(comparison_object)
        self == (comparison_object)
      end

      # Delegates to id in order to allow two records of the same type and id to work with something like:
      #   [ Person.find(1), Person.find(2), Person.find(3) ] & [ Person.find(1), Person.find(4) ] # => [ Person.find(1) ]
      def hash
        id.hash
      end

      # Freeze the attributes hash such that associations are still accessible, even on destroyed records.
      def freeze
        @attributes.freeze; self
      end

      # Returns +true+ if the attributes hash has been frozen.
      def frozen?
        @attributes.frozen?
      end

      # Returns duplicated record with unfreezed attributes.
      def dup
        obj = super
        obj.instance_variable_set('@attributes', @attributes.dup)
        obj
      end

      # Returns +true+ if the record is read only. Records loaded through joins with piggy-back
      # attributes will be marked as read only since they cannot be saved.
      def readonly?
        @readonly
      end

      # Marks this record as read only.
      def readonly!
        @readonly = true
      end

      # Returns the contents of the record as a nicely formatted string.
      def inspect
        attributes_as_nice_string = self.class.column_names.collect { |name|
          if has_attribute?(name) || new_record?
            "#{name}: #{attribute_for_inspect(name)}"
          end
        }.compact.join(", ")
        "#<#{self.class} #{attributes_as_nice_string}>"
      end

    protected
      def clone_attributes(reader_method = :read_attribute, attributes = {})
        attribute_names.each do |name|
          attributes[name] = clone_attribute_value(reader_method, name)
        end
        attributes
      end

      def clone_attribute_value(reader_method, attribute_name)
        value = send(reader_method, attribute_name)
        value.duplicable? ? value.clone : value
      rescue TypeError, NoMethodError
        value
      end

    private
      def create_or_update
        raise ReadOnlyRecord if readonly?
        result = new_record? ? create : update
        result != false
      end

      # Updates the associated record with values matching those of the instance attributes.
      # Returns the number of affected rows.
      def update(attribute_names = @attributes.keys)
        attributes_with_values = arel_attributes_values(false, false, attribute_names)
        return 0 if attributes_with_values.empty?
        self.class.unscoped.where(self.class.arel_table[self.class.primary_key].eq(id)).arel.update(attributes_with_values)
      end

      # Creates a record with values matching those of the instance attributes
      # and returns its id.
      def create
        if self.id.nil? && connection.prefetch_primary_key?(self.class.table_name)
          self.id = connection.next_sequence_value(self.class.sequence_name)
        end

        attributes_values = arel_attributes_values

        new_id = if attributes_values.empty?
          self.class.unscoped.insert connection.empty_insert_statement_value
        else
          self.class.unscoped.insert attributes_values
        end

        self.id ||= new_id

        @new_record = false
        id
      end

      # Sets the attribute used for single table inheritance to this class name if this is not the ActiveRecord::Base descendant.
      # Considering the hierarchy Reply < Message < ActiveRecord::Base, this makes it possible to do Reply.new without having to
      # set <tt>Reply[Reply.inheritance_column] = "Reply"</tt> yourself. No such attribute would be set for objects of the
      # Message class in that example.
      def ensure_proper_type
        unless self.class.descends_from_active_record?
          write_attribute(self.class.inheritance_column, self.class.sti_name)
        end
      end

      def remove_attributes_protected_from_mass_assignment(attributes)
        safe_attributes =
          if self.class.accessible_attributes.nil? && self.class.protected_attributes.nil?
            attributes.reject { |key, value| attributes_protected_by_default.include?(key.gsub(/\(.+/, "")) }
          elsif self.class.protected_attributes.nil?
            attributes.reject { |key, value| !self.class.accessible_attributes.include?(key.gsub(/\(.+/, "")) || attributes_protected_by_default.include?(key.gsub(/\(.+/, "")) }
          elsif self.class.accessible_attributes.nil?
            attributes.reject { |key, value| self.class.protected_attributes.include?(key.gsub(/\(.+/,"")) || attributes_protected_by_default.include?(key.gsub(/\(.+/, "")) }
          else
            raise "Declare either attr_protected or attr_accessible for #{self.class}, but not both."
          end

        removed_attributes = attributes.keys - safe_attributes.keys

        if removed_attributes.any?
          log_protected_attribute_removal(removed_attributes)
        end

        safe_attributes
      end

      # Removes attributes which have been marked as readonly.
      def remove_readonly_attributes(attributes)
        unless self.class.readonly_attributes.nil?
          attributes.delete_if { |key, value| self.class.readonly_attributes.include?(key.gsub(/\(.+/,"")) }
        else
          attributes
        end
      end

      def log_protected_attribute_removal(*attributes)
        if logger
          logger.debug "WARNING: Can't mass-assign these protected attributes: #{attributes.join(', ')}"
        end
      end

      # The primary key and inheritance column can never be set by mass-assignment for security reasons.
      def attributes_protected_by_default
        default = [ self.class.primary_key, self.class.inheritance_column ]
        default << 'id' unless self.class.primary_key.eql? 'id'
        default
      end

      # Returns a copy of the attributes hash where all the values have been safely quoted for use in
      # an Arel insert/update method.
      def arel_attributes_values(include_primary_key = true, include_readonly_attributes = true, attribute_names = @attributes.keys)
        attrs = {}
        attribute_names.each do |name|
          if (column = column_for_attribute(name)) && (include_primary_key || !column.primary)

            if include_readonly_attributes || (!include_readonly_attributes && !self.class.readonly_attributes.include?(name))
              value = read_attribute(name)

              if value && ((self.class.serialized_attributes.has_key?(name) && (value.acts_like?(:date) || value.acts_like?(:time))) || value.is_a?(Hash) || value.is_a?(Array))
                value = value.to_yaml
              end
              attrs[self.class.arel_table[name]] = value
            end
          end
        end
        attrs
      end

      # Quote strings appropriately for SQL statements.
      def quote_value(value, column = nil)
        self.class.connection.quote(value, column)
      end

      # Interpolate custom SQL string in instance context.
      # Optional record argument is meant for custom insert_sql.
      def interpolate_sql(sql, record = nil)
        instance_eval("%@#{sql.gsub('@', '\@')}@")
      end

      # Initializes the attributes array with keys matching the columns from the linked table and
      # the values matching the corresponding default value of that column, so
      # that a new instance, or one populated from a passed-in Hash, still has all the attributes
      # that instances loaded from the database would.
      def attributes_from_column_definition
        self.class.columns.inject({}) do |attributes, column|
          attributes[column.name] = column.default unless column.name == self.class.primary_key
          attributes
        end
      end

      # Instantiates objects for all attribute classes that needs more than one constructor parameter. This is done
      # by calling new on the column type or aggregation type (through composed_of) object with these parameters.
      # So having the pairs written_on(1) = "2004", written_on(2) = "6", written_on(3) = "24", will instantiate
      # written_on (a date type) with Date.new("2004", "6", "24"). You can also specify a typecast character in the
      # parentheses to have the parameters typecasted before they're used in the constructor. Use i for Fixnum, f for Float,
      # s for String, and a for Array. If all the values for a given attribute are empty, the attribute will be set to nil.
      def assign_multiparameter_attributes(pairs)
        execute_callstack_for_multiparameter_attributes(
          extract_callstack_for_multiparameter_attributes(pairs)
        )
      end

      def instantiate_time_object(name, values)
        if self.class.send(:create_time_zone_conversion_attribute?, name, column_for_attribute(name))
          Time.zone.local(*values)
        else
          Time.time_with_datetime_fallback(@@default_timezone, *values)
        end
      end

      def execute_callstack_for_multiparameter_attributes(callstack)
        errors = []
        callstack.each do |name, values_with_empty_parameters|
          begin
            klass = (self.class.reflect_on_aggregation(name.to_sym) || column_for_attribute(name)).klass
            # in order to allow a date to be set without a year, we must keep the empty values.
            # Otherwise, we wouldn't be able to distinguish it from a date with an empty day.
            values = values_with_empty_parameters.reject(&:nil?)

            if values.empty?
              send(name + "=", nil)
            else

              value = if Time == klass
                instantiate_time_object(name, values)
              elsif Date == klass
                begin
                  values = values_with_empty_parameters.collect do |v| v.nil? ? 1 : v end
                  Date.new(*values)
                rescue ArgumentError => ex # if Date.new raises an exception on an invalid date
                  instantiate_time_object(name, values).to_date # we instantiate Time object and convert it back to a date thus using Time's logic in handling invalid dates
                end
              else
                klass.new(*values)
              end

              send(name + "=", value)
            end
          rescue => ex
            errors << AttributeAssignmentError.new("error on assignment #{values.inspect} to #{name}", ex, name)
          end
        end
        unless errors.empty?
          raise MultiparameterAssignmentErrors.new(errors), "#{errors.size} error(s) on assignment of multiparameter attributes"
        end
      end

      def extract_callstack_for_multiparameter_attributes(pairs)
        attributes = { }

        for pair in pairs
          multiparameter_name, value = pair
          attribute_name = multiparameter_name.split("(").first
          attributes[attribute_name] = [] unless attributes.include?(attribute_name)

          parameter_value = value.empty? ? nil : type_cast_attribute_value(multiparameter_name, value)
          attributes[attribute_name] << [ find_parameter_position(multiparameter_name), parameter_value ]
        end

        attributes.each { |name, values| attributes[name] = values.sort_by{ |v| v.first }.collect { |v| v.last } }
      end

      def type_cast_attribute_value(multiparameter_name, value)
        multiparameter_name =~ /\([0-9]*([if])\)/ ? value.send("to_" + $1) : value
      end

      def find_parameter_position(multiparameter_name)
        multiparameter_name.scan(/\(([0-9]*).*\)/).first.first
      end

      # Returns a comma-separated pair list, like "key1 = val1, key2 = val2".
      def comma_pair_list(hash)
        hash.map { |k,v| "#{k} = #{v}" }.join(", ")
      end

      def quote_columns(quoter, hash)
        hash.inject({}) do |quoted, (name, value)|
          quoted[quoter.quote_column_name(name)] = value
          quoted
        end
      end

      def quoted_comma_pair_list(quoter, hash)
        comma_pair_list(quote_columns(quoter, hash))
      end

      def convert_number_column_value(value)
        if value == false
          0
        elsif value == true
          1
        elsif value.is_a?(String) && value.blank?
          nil
        else
          value
        end
      end

      def object_from_yaml(string)
        return string unless string.is_a?(String) && string =~ /^---/
        YAML::load(string) rescue string
      end
  end

  Base.class_eval do
    extend ActiveModel::Naming
    extend QueryCache::ClassMethods
    extend ActiveSupport::Benchmarkable

    include ActiveModel::Conversion
    include Validations
    include Locking::Optimistic, Locking::Pessimistic
    include AttributeMethods
    include AttributeMethods::Read, AttributeMethods::Write, AttributeMethods::BeforeTypeCast, AttributeMethods::Query
    include AttributeMethods::PrimaryKey
    include AttributeMethods::TimeZoneConversion
    include AttributeMethods::Dirty
    include Callbacks, ActiveModel::Observing, Timestamp
    include Associations, AssociationPreload, NamedScope

    # AutosaveAssociation needs to be included before Transactions, because we want
    # #save_with_autosave_associations to be wrapped inside a transaction.
    include AutosaveAssociation, NestedAttributes
    include Aggregations, Transactions, Reflection, Serialization

    NilClass.add_whiner(self) if NilClass.respond_to?(:add_whiner)
  end
end

# TODO: Remove this and make it work with LAZY flag
require 'active_record/connection_adapters/abstract_adapter'
ActiveSupport.run_load_hooks(:active_record, ActiveRecord::Base)