aboutsummaryrefslogtreecommitdiffstats
path: root/activerecord/lib/active_record/reflection.rb
blob: 0310e7050d11c31ee7afee7b23a696c6d282714f (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
require 'active_support/core_ext/class/attribute'

module ActiveRecord
  # = Active Record Reflection
  module Reflection # :nodoc:
    extend ActiveSupport::Concern

    included do
      class_attribute :reflections
      self.reflections = {}
    end

    # Reflection enables to interrogate Active Record classes and objects
    # about their associations and aggregations. This information can,
    # for example, be used in a form builder that takes an Active Record object
    # and creates input fields for all of the attributes depending on their type
    # and displays the associations to other objects.
    #
    # MacroReflection class has info for AggregateReflection and AssociationReflection
    # classes.
    module ClassMethods
      def create_reflection(macro, name, options, active_record)
        case macro
          when :has_many, :belongs_to, :has_one, :has_and_belongs_to_many
            klass = options[:through] ? ThroughReflection : AssociationReflection
            reflection = klass.new(macro, name, options, active_record)
          when :composed_of
            reflection = AggregateReflection.new(macro, name, options, active_record)
        end

        self.reflections = self.reflections.merge(name => reflection)
        reflection
      end

      # Returns an array of AggregateReflection objects for all the aggregations in the class.
      def reflect_on_all_aggregations
        reflections.values.grep(AggregateReflection)
      end

      # Returns the AggregateReflection object for the named +aggregation+ (use the symbol).
      #
      #   Account.reflect_on_aggregation(:balance) # => the balance AggregateReflection
      #
      def reflect_on_aggregation(aggregation)
        reflections[aggregation].is_a?(AggregateReflection) ? reflections[aggregation] : nil
      end

      # Returns an array of AssociationReflection objects for all the
      # associations in the class. If you only want to reflect on a certain
      # association type, pass in the symbol (<tt>:has_many</tt>, <tt>:has_one</tt>,
      # <tt>:belongs_to</tt>) as the first parameter.
      #
      # Example:
      #
      #   Account.reflect_on_all_associations             # returns an array of all associations
      #   Account.reflect_on_all_associations(:has_many)  # returns an array of all has_many associations
      #
      def reflect_on_all_associations(macro = nil)
        association_reflections = reflections.values.grep(AssociationReflection)
        macro ? association_reflections.select { |reflection| reflection.macro == macro } : association_reflections
      end

      # Returns the AssociationReflection object for the +association+ (use the symbol).
      #
      #   Account.reflect_on_association(:owner)             # returns the owner AssociationReflection
      #   Invoice.reflect_on_association(:line_items).macro  # returns :has_many
      #
      def reflect_on_association(association)
        reflections[association].is_a?(AssociationReflection) ? reflections[association] : nil
      end

      # Returns an array of AssociationReflection objects for all associations which have <tt>:autosave</tt> enabled.
      def reflect_on_all_autosave_associations
        reflections.values.select { |reflection| reflection.options[:autosave] }
      end
    end


    # Abstract base class for AggregateReflection and AssociationReflection. Objects of
    # AggregateReflection and AssociationReflection are returned by the Reflection::ClassMethods.
    class MacroReflection
      attr_reader :active_record

      def initialize(macro, name, options, active_record)
        @macro, @name, @options, @active_record = macro, name, options, active_record
      end

      # Returns the name of the macro.
      #
      # <tt>composed_of :balance, :class_name => 'Money'</tt> returns <tt>:balance</tt>
      # <tt>has_many :clients</tt> returns <tt>:clients</tt>
      attr_reader :name

      # Returns the macro type.
      #
      # <tt>composed_of :balance, :class_name => 'Money'</tt> returns <tt>:composed_of</tt>
      # <tt>has_many :clients</tt> returns <tt>:has_many</tt>
      attr_reader :macro

      # Returns the hash of options used for the macro.
      #
      # <tt>composed_of :balance, :class_name => 'Money'</tt> returns <tt>{ :class_name => "Money" }</tt>
      # <tt>has_many :clients</tt> returns +{}+
      attr_reader :options

      # Returns the class for the macro.
      #
      # <tt>composed_of :balance, :class_name => 'Money'</tt> returns the Money class
      # <tt>has_many :clients</tt> returns the Client class
      def klass
        @klass ||= class_name.constantize
      end

      # Returns the class name for the macro.
      #
      # <tt>composed_of :balance, :class_name => 'Money'</tt> returns <tt>'Money'</tt>
      # <tt>has_many :clients</tt> returns <tt>'Client'</tt>
      def class_name
        @class_name ||= options[:class_name] || derive_class_name
      end

      # Returns +true+ if +self+ and +other_aggregation+ have the same +name+ attribute, +active_record+ attribute,
      # and +other_aggregation+ has an options hash assigned to it.
      def ==(other_aggregation)
        other_aggregation.kind_of?(self.class) && name == other_aggregation.name && other_aggregation.options && active_record == other_aggregation.active_record
      end

      def sanitized_conditions #:nodoc:
        @sanitized_conditions ||= klass.send(:sanitize_sql, options[:conditions]) if options[:conditions]
      end

      private
        def derive_class_name
          name.to_s.camelize
        end
    end


    # Holds all the meta-data about an aggregation as it was specified in the
    # Active Record class.
    class AggregateReflection < MacroReflection #:nodoc:
    end

    # Holds all the meta-data about an association as it was specified in the
    # Active Record class.
    class AssociationReflection < MacroReflection #:nodoc:
      # Returns the target association's class.
      #
      #   class Author < ActiveRecord::Base
      #     has_many :books
      #   end
      #
      #   Author.reflect_on_association(:books).klass
      #   # => Book
      #
      # <b>Note:</b> Do not call +klass.new+ or +klass.create+ to instantiate
      # a new association object. Use +build_association+ or +create_association+
      # instead. This allows plugins to hook into association object creation.
      def klass
        @klass ||= active_record.send(:compute_type, class_name)
      end

      def initialize(macro, name, options, active_record)
        super
        @collection = [:has_many, :has_and_belongs_to_many].include?(macro)
      end

      # Returns a new, unsaved instance of the associated class. +options+ will
      # be passed to the class's constructor.
      def build_association(*options)
        klass.new(*options)
      end

      # Creates a new instance of the associated class, and immediately saves it
      # with ActiveRecord::Base#save. +options+ will be passed to the class's
      # creation method. Returns the newly created object.
      def create_association(*options)
        klass.create(*options)
      end

      # Creates a new instance of the associated class, and immediately saves it
      # with ActiveRecord::Base#save!. +options+ will be passed to the class's
      # creation method. If the created record doesn't pass validations, then an
      # exception will be raised.
      #
      # Returns the newly created object.
      def create_association!(*options)
        klass.create!(*options)
      end

      def table_name
        @table_name ||= klass.table_name
      end

      def quoted_table_name
        @quoted_table_name ||= klass.quoted_table_name
      end

      def primary_key_name
        @primary_key_name ||= options[:foreign_key] || derive_primary_key_name
      end

      def primary_key_column
        @primary_key_column ||= klass.columns.find { |c| c.name == klass.primary_key }
      end

      def association_foreign_key
        @association_foreign_key ||= options[:association_foreign_key] || class_name.foreign_key
      end

      def association_primary_key
        @association_primary_key ||=
          options[:primary_key] ||
          !options[:polymorphic] && klass.primary_key ||
          'id'
      end

      def active_record_primary_key
        @active_record_primary_key ||= options[:primary_key] || active_record.primary_key
      end

      def counter_cache_column
        if options[:counter_cache] == true
          "#{active_record.name.demodulize.underscore.pluralize}_count"
        elsif options[:counter_cache]
          options[:counter_cache]
        end
      end

      def columns(tbl_name, log_msg)
        @columns ||= klass.connection.columns(tbl_name, log_msg)
      end

      def reset_column_information
        @columns = nil
      end

      def check_validity!
        check_validity_of_inverse!
      end

      def check_validity_of_inverse!
        unless options[:polymorphic]
          if has_inverse? && inverse_of.nil?
            raise InverseOfAssociationNotFoundError.new(self)
          end
        end
      end

      def through_reflection
        false
      end

      def through_reflection_primary_key_name
      end

      def source_reflection
        nil
      end

      def has_inverse?
        @options[:inverse_of]
      end

      def inverse_of
        if has_inverse?
          @inverse_of ||= klass.reflect_on_association(options[:inverse_of])
        end
      end

      def polymorphic_inverse_of(associated_class)
        if has_inverse?
          if inverse_relationship = associated_class.reflect_on_association(options[:inverse_of])
            inverse_relationship
          else
            raise InverseOfAssociationNotFoundError.new(self, associated_class)
          end
        end
      end

      # Returns whether or not this association reflection is for a collection
      # association. Returns +true+ if the +macro+ is either +has_many+ or
      # +has_and_belongs_to_many+, +false+ otherwise.
      def collection?
        @collection
      end

      # Returns whether or not the association should be validated as part of
      # the parent's validation.
      #
      # Unless you explicitly disable validation with
      # <tt>:validate => false</tt>, validation will take place when:
      #
      # * you explicitly enable validation; <tt>:validate => true</tt>
      # * you use autosave; <tt>:autosave => true</tt>
      # * the association is a +has_many+ association
      def validate?
        !options[:validate].nil? ? options[:validate] : (options[:autosave] == true || macro == :has_many)
      end

      def dependent_conditions(record, base_class, extra_conditions)
        dependent_conditions = []
        dependent_conditions << "#{primary_key_name} = #{record.send(name).send(:owner_quoted_id)}"
        dependent_conditions << "#{options[:as]}_type = '#{base_class.name}'" if options[:as]
        dependent_conditions << klass.send(:sanitize_sql, options[:conditions]) if options[:conditions]
        dependent_conditions << extra_conditions if extra_conditions
        dependent_conditions = dependent_conditions.collect {|where| "(#{where})" }.join(" AND ")
        dependent_conditions = dependent_conditions.gsub('@', '\@')
        dependent_conditions
      end

      # Returns +true+ if +self+ is a +belongs_to+ reflection.
      def belongs_to?
        macro == :belongs_to
      end

      private
        def derive_class_name
          class_name = name.to_s.camelize
          class_name = class_name.singularize if collection?
          class_name
        end

        def derive_primary_key_name
          if belongs_to?
            "#{name}_id"
          elsif options[:as]
            "#{options[:as]}_id"
          else
            active_record.name.foreign_key
          end
        end
    end

    # Holds all the meta-data about a :through association as it was specified
    # in the Active Record class.
    class ThroughReflection < AssociationReflection #:nodoc:
      # Gets the source of the through reflection.  It checks both a singularized
      # and pluralized form for <tt>:belongs_to</tt> or <tt>:has_many</tt>.
      #
      #   class Post < ActiveRecord::Base
      #     has_many :taggings
      #     has_many :tags, :through => :taggings
      #   end
      #
      def source_reflection
        @source_reflection ||= source_reflection_names.collect { |name| through_reflection.klass.reflect_on_association(name) }.compact.first
      end

      # Returns the AssociationReflection object specified in the <tt>:through</tt> option
      # of a HasManyThrough or HasOneThrough association.
      #
      #   class Post < ActiveRecord::Base
      #     has_many :taggings
      #     has_many :tags, :through => :taggings
      #   end
      #
      #   tags_reflection = Post.reflect_on_association(:tags)
      #   taggings_reflection = tags_reflection.through_reflection
      #
      def through_reflection
        @through_reflection ||= active_record.reflect_on_association(options[:through])
      end

      # Gets an array of possible <tt>:through</tt> source reflection names:
      #
      #   [:singularized, :pluralized]
      #
      def source_reflection_names
        @source_reflection_names ||= (options[:source] ? [options[:source]] : [name.to_s.singularize, name]).collect { |n| n.to_sym }
      end

      def check_validity!
        if through_reflection.nil?
          raise HasManyThroughAssociationNotFoundError.new(active_record.name, self)
        end

        if through_reflection.options[:polymorphic]
          raise HasManyThroughAssociationPolymorphicThroughError.new(active_record.name, self)
        end

        if source_reflection.nil?
          raise HasManyThroughSourceAssociationNotFoundError.new(self)
        end

        if options[:source_type] && source_reflection.options[:polymorphic].nil?
          raise HasManyThroughAssociationPointlessSourceTypeError.new(active_record.name, self, source_reflection)
        end

        if source_reflection.options[:polymorphic] && options[:source_type].nil?
          raise HasManyThroughAssociationPolymorphicSourceError.new(active_record.name, self, source_reflection)
        end

        unless [:belongs_to, :has_many, :has_one].include?(source_reflection.macro) && source_reflection.options[:through].nil?
          raise HasManyThroughSourceAssociationMacroError.new(self)
        end

        if macro == :has_one && through_reflection.collection?
          raise HasOneThroughCantAssociateThroughCollection.new(active_record.name, self, through_reflection)
        end

        check_validity_of_inverse!
      end

      def through_reflection_primary_key
        through_reflection.belongs_to? ? through_reflection.klass.primary_key : through_reflection.primary_key_name
      end

      def through_reflection_primary_key_name
        through_reflection.primary_key_name if through_reflection.belongs_to?
      end

      private
        def derive_class_name
          # get the class_name of the belongs_to association of the through reflection
          options[:source_type] || source_reflection.class_name
        end
    end
  end
end