Make AssociationCollection start transactions in the correct database.

AssociationCollection now starts transactions by calling
AssociationCollection#transaction instead of @owner.transaction or
@reflection.klass.transaction.

Signed-off-by: Michael Koziarski <michael@koziarski.com>

[#1081 state:committed]

activerecord/lib/active_record/associations/association_collection.rb

@@ -108,7 +108,7 @@ def <<(*records)
         result = true
         load_target if @owner.new_record?
 
-        @owner.transaction do
+        transaction do
           flatten_deeper(records).each do |record|
             raise_on_type_mismatch(record)
             add_record_to_target_with_callbacks(record) do |r|
@@ -123,6 +123,21 @@ def <<(*records)
       alias_method :push, :<<
       alias_method :concat, :<<
 
+      # Starts a transaction in the association class's database connection.
+      #
+      #   class Author < ActiveRecord::Base
+      #     has_many :books
+      #   end
+      #
+      #   Author.find(:first).books.transaction do
+      #     # same effect as calling Book.transaction
+      #   end
+      def transaction(*args)
+        @reflection.klass.transaction(*args) do
+          yield
+        end
+      end
+
       # Remove all records from this association
       def delete_all
         load_target
@@ -173,7 +188,7 @@ def delete(*records)
         records = flatten_deeper(records)
         records.each { |record| raise_on_type_mismatch(record) }
 
-        @owner.transaction do
+        transaction do
           records.each { |record| callback(:before_remove, record) }
 
           old_records = records.reject {|r| r.new_record? }
@@ -200,7 +215,7 @@ def clear
       end
 
       def destroy_all
-        @owner.transaction do
+        transaction do
           each { |record| record.destroy }
         end
 
@@ -292,7 +307,7 @@ def replace(other_array)
         other   = other_array.size < 100 ? other_array : other_array.to_set
         current = @target.size < 100 ? @target : @target.to_set
 
-        @owner.transaction do
+        transaction do
           delete(@target.select { |v| !other.include?(v) })
           concat(other_array.select { |v| !current.include?(v) })
         end

activerecord/lib/active_record/associations/has_many_through_association.rb

@@ -9,14 +9,14 @@ def initialize(owner, reflection)
       alias_method :new, :build
 
       def create!(attrs = nil)
-        @reflection.klass.transaction do
+        transaction do
           self << (object = attrs ? @reflection.klass.send(:with_scope, :create => attrs) { @reflection.create_association! } : @reflection.create_association!)
           object
         end
       end
 
       def create(attrs = nil)
-        @reflection.klass.transaction do
+        transaction do
           self << (object = attrs ? @reflection.klass.send(:with_scope, :create => attrs) { @reflection.create_association } : @reflection.create_association)
           object
         end

activerecord/test/cases/associations/has_and_belongs_to_many_associations_test.rb

@@ -738,4 +738,13 @@ def test_counting_on_habtm_association_and_not_array
     # Array#count in Ruby >=1.8.7, which would raise an ArgumentError
     assert_nothing_raised { david.projects.count(:all, :conditions => '1=1') }
   end
+
+  uses_mocha 'mocking Post.transaction' do
+    def test_association_proxy_transaction_method_starts_transaction_in_association_class
+      Post.expects(:transaction)
+      Category.find(:first).posts.transaction do
+        # nothing
+      end
+    end
+  end
 end

activerecord/test/cases/associations/has_many_associations_test.rb

@@ -1071,4 +1071,13 @@ def test_joins_with_namespaced_model_should_use_correct_type
     ActiveRecord::Base.store_full_sti_class = old
   end
 
+  uses_mocha 'mocking Comment.transaction' do
+    def test_association_proxy_transaction_method_starts_transaction_in_association_class
+      Comment.expects(:transaction)
+      Post.find(:first).comments.transaction do
+        # nothing
+      end
+    end
+  end
+
 end

activerecord/test/cases/associations/has_many_through_associations_test.rb

@@ -220,4 +220,13 @@ def test_get_ids_for_unloaded_associations_does_not_load_them
     assert_equal [posts(:welcome).id, posts(:authorless).id].sort, person.post_ids.sort
     assert !person.posts.loaded?
   end
+
+  uses_mocha 'mocking Tag.transaction' do
+    def test_association_proxy_transaction_method_starts_transaction_in_association_class
+      Tag.expects(:transaction)
+      Post.find(:first).tags.transaction do
+        # nothing
+      end
+    end
+  end
 end