Merge pull request rails#14234 from arthurnn/fix_trans_on_replace

Remove unnecessary db call when replacing.
steamrolly · Mar 1, 2014 · f60b524 · f60b524
2 parents f160107 + 774160b
commit f60b524
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Showing 2 changed files with 13 additions and 1 deletion.
diff --git a/activerecord/lib/active_record/associations/collection_association.rb b/activerecord/lib/active_record/associations/collection_association.rb
@@ -359,7 +359,9 @@ def replace(other_array)
         if owner.new_record?
           replace_records(other_array, original_target)
         else
-          transaction { replace_records(other_array, original_target) }
+          if other_array != original_target
+            transaction { replace_records(other_array, original_target) }
+          end
         end
       end
 

diff --git a/activerecord/test/cases/associations/has_many_associations_test.rb b/activerecord/test/cases/associations/has_many_associations_test.rb
@@ -1242,6 +1242,16 @@ def test_replace_failure
     assert_equal orig_accounts, firm.accounts
   end
 
+  def test_replace_with_same_content
+    firm = Firm.first
+    firm.clients = []
+    firm.save
+
+    assert_queries(0, ignore_none: true) do
+      firm.clients = []
+    end
+  end
+
   def test_transactions_when_replacing_on_persisted
     good = Client.new(:name => "Good")
     bad  = Client.new(:name => "Bad", :raise_on_save => true)