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
|
module ActiveRecord
# = Active Record Counter Cache
module CounterCache
extend ActiveSupport::Concern
module ClassMethods
# 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 association counters to reset. Association name or counter name can be given.
#
# ==== 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 |counter_association|
has_many_association = _reflect_on_association(counter_association.to_sym)
unless has_many_association
has_many = reflect_on_all_associations(:has_many)
has_many_association = has_many.find { |association| association.counter_cache_column && association.counter_cache_column.to_sym == counter_association.to_sym }
counter_association = has_many_association.plural_name if has_many_association
end
raise ArgumentError, "'#{self.name}' has no association called '#{counter_association}'" unless has_many_association
if has_many_association.is_a? ActiveRecord::Reflection::ThroughReflection
has_many_association = has_many_association.through_reflection
end
foreign_key = has_many_association.foreign_key.to_s
child_class = has_many_association.klass
reflection = child_class._reflections.values.find { |e| :belongs_to == e.macro && e.foreign_key.to_s == foreign_key && e.options[:counter_cache].present? }
counter_name = reflection.counter_cache_column
stmt = unscoped.where(arel_table[primary_key].eq(object.id)).arel.compile_update({
arel_table[counter_name] => object.send(counter_association).count(:all)
}, primary_key)
connection.update stmt
end
return true
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+ - A Hash 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 = COALESCE(comment_count, 0) - 1,
# # action_count = COALESCE(action_count, 0) + 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 = COALESCE(comment_count, 0) + 1
# # WHERE id IN (10, 15)
def update_counters(id, counters)
updates = counters.map do |counter_name, value|
operator = value < 0 ? '-' : '+'
quoted_column = connection.quote_column_name(counter_name)
"#{quoted_column} = COALESCE(#{quoted_column}, 0) #{operator} #{value.abs}"
end
unscoped.where(primary_key => id).update_all updates.join(', ')
end
# Increment a numeric field by one, via a direct SQL update.
#
# This method is used primarily for maintaining counter_cache columns that are
# used to store aggregate values. For example, a DiscussionBoard may cache
# posts_count and comments_count to avoid running an SQL query to calculate the
# number of posts and comments there are, each time it is displayed.
#
# ==== Parameters
#
# * +counter_name+ - The name of the field that should be incremented.
# * +id+ - The id of the object that should be incremented or an Array of ids.
#
# ==== 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 numeric field by one, via a direct SQL update.
#
# 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 or an Array of ids.
#
# ==== 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
end
protected
def actually_destroyed?
@_actually_destroyed
end
def clear_destroy_state
@_actually_destroyed = nil
end
private
def _create_record(*)
id = super
each_counter_cached_associations do |association|
if send(association.reflection.name)
association.increment_counters
@_after_create_counter_called = true
end
end
id
end
def destroy_row
affected_rows = super
if affected_rows > 0
each_counter_cached_associations do |association|
foreign_key = association.reflection.foreign_key.to_sym
unless destroyed_by_association && destroyed_by_association.foreign_key.to_sym == foreign_key
if send(association.reflection.name)
association.decrement_counters
end
end
end
end
affected_rows
end
def each_counter_cached_associations
_reflections.each do |name, reflection|
yield association(name) if reflection.belongs_to? && reflection.counter_cache_column
end
end
end
end
|
