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Merge pull request #9737 from wangjohn/counter_cache_update_attribute…

…s_fix

The counter cache will now work correctly when the foreign key is changed. Fixes #9722.
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2 parents ae8e84e + 455d710 commit 34be80443c76dde393ae5e2b28805bd01605eadc @jeremy jeremy committed Mar 15, 2013
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26 activerecord/CHANGELOG.md
@@ -1,5 +1,31 @@
## Rails 4.0.0 (unreleased) ##
+* Counter caches on associations will now stay valid when attributes are
+ updated (not just when records are created or destroyed), for example,
+ when calling +update_attributes+. The following code now works:
+
+ class Comment < ActiveRecord::Base
+ belongs_to :post, counter_cache: true
+ end
+
+ class Post < ActiveRecord::Base
+ has_many :comments
+ end
+
+ post = Post.create
+ comment = Comment.create
+
+ post.comments << comment
+ post.save.reload.comments_count # => 1
+ comment.update_attributes(:post_id => nil)
+
+ post.save.reload.comments_count # => 0
+
+ Updating the id of a +belongs_to+ object with the id of a new object will
+ also keep the count accurate.
+
+ *John Wang*
+
* Referencing join tables implicitly was deprecated. There is a
possibility that these deprecation warnings are shown even if you
don't make use of that feature. You can now disable the feature entirely.
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20 activerecord/lib/active_record/associations/builder/belongs_to.rb
@@ -21,11 +21,13 @@ def build
def add_counter_cache_callbacks(reflection)
cache_column = reflection.counter_cache_column
+ foreign_key = reflection.foreign_key
mixin.class_eval <<-CODE, __FILE__, __LINE__ + 1
def belongs_to_counter_cache_after_create_for_#{name}
record = #{name}
record.class.increment_counter(:#{cache_column}, record.id) unless record.nil?
+ @_after_create_counter_called = true
end
def belongs_to_counter_cache_before_destroy_for_#{name}
@@ -34,10 +36,28 @@ def belongs_to_counter_cache_before_destroy_for_#{name}
record.class.decrement_counter(:#{cache_column}, record.id) unless record.nil?
end
end
+
+ def belongs_to_counter_cache_after_update_for_#{name}
+ if (@_after_create_counter_called ||= false)
+ @_after_create_counter_called = false
+ elsif self.#{foreign_key}_changed? && !new_record? && defined?(#{name.to_s.camelize})
+ model = #{name.to_s.camelize}
+ foreign_key_was = self.#{foreign_key}_was
+ foreign_key = self.#{foreign_key}
+
+ if foreign_key && model.respond_to?(:increment_counter)
+ model.increment_counter(:#{cache_column}, foreign_key)
+ end
+ if foreign_key_was && model.respond_to?(:decrement_counter)
+ model.decrement_counter(:#{cache_column}, foreign_key_was)
+ end
+ end
+ end
CODE
model.after_create "belongs_to_counter_cache_after_create_for_#{name}"
model.before_destroy "belongs_to_counter_cache_before_destroy_for_#{name}"
+ model.after_update "belongs_to_counter_cache_after_update_for_#{name}"
klass = reflection.class_name.safe_constantize
klass.attr_readonly cache_column if klass && klass.respond_to?(:attr_readonly)
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31 activerecord/test/cases/associations/has_many_associations_test.rb
@@ -789,6 +789,37 @@ def test_custom_named_counter_cache
end
end
+ def test_calling_update_attributes_on_id_changes_the_counter_cache
+ topic = Topic.order("id ASC").first
+ original_count = topic.replies.to_a.size
+ assert_equal original_count, topic.replies_count
+
+ first_reply = topic.replies.first
+ first_reply.update_attributes(:parent_id => nil)
+ assert_equal original_count - 1, topic.reload.replies_count
+
+ first_reply.update_attributes(:parent_id => topic.id)
+ assert_equal original_count, topic.reload.replies_count
+ end
+
+ def test_calling_update_attributes_changing_ids_doesnt_change_counter_cache
+ topic1 = Topic.find(1)
+ topic2 = Topic.find(3)
+ original_count1 = topic1.replies.to_a.size
+ original_count2 = topic2.replies.to_a.size
+
+ reply1 = topic1.replies.first
+ reply2 = topic2.replies.first
+
+ reply1.update_attributes(:parent_id => topic2.id)
+ assert_equal original_count1 - 1, topic1.reload.replies_count
+ assert_equal original_count2 + 1, topic2.reload.replies_count
+
+ reply2.update_attributes(:parent_id => topic1.id)
+ assert_equal original_count1, topic1.reload.replies_count
+ assert_equal original_count2, topic2.reload.replies_count
+ end
+
def test_deleting_a_collection
force_signal37_to_load_all_clients_of_firm
companies(:first_firm).clients_of_firm.create("name" => "Another Client")

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