2 files changed, 30 insertions, 3 deletions
diff --git a/activerecord/lib/active_record/associations/collection_proxy.rb b/activerecord/lib/active_record/associations/collection_proxy.rb
index 388173c1fb..adfc71d435 100644
--- a/activerecord/lib/active_record/associations/collection_proxy.rb
+++ b/activerecord/lib/active_record/associations/collection_proxy.rb
@@ -64,9 +64,12 @@ module ActiveRecord
 
       def method_missing(method, *args, &block)
         match = DynamicFinderMatch.match(method)
-        if match && match.creator?
-          attributes = match.attribute_names
-          return send(:"find_by_#{attributes.join('_and_')}", *args) || create(Hash[attributes.zip(args)])
+        if match && match.instantiator?
+          record = send(:find_or_instantiator_by_attributes, match, match.attribute_names, *args) do |r|
+            @association.send :set_owner_attributes, r
+            @association.send :add_to_target, r
+            yield(r) if block_given?
+          end
         end
 
         if target.respond_to?(method) || (!@association.klass.respond_to?(method) && Class.respond_to?(method))
diff --git a/activerecord/test/cases/associations/has_many_associations_test.rb b/activerecord/test/cases/associations/has_many_associations_test.rb
index 007f11b535..247decc67b 100644
--- a/activerecord/test/cases/associations/has_many_associations_test.rb
+++ b/activerecord/test/cases/associations/has_many_associations_test.rb
@@ -605,6 +605,30 @@ class HasManyAssociationsTest < ActiveRecord::TestCase
     assert_equal number_of_clients + 1, companies(:first_firm, :reload).clients.size
   end
 
+  def test_find_or_initialize_updates_collection_size
+    number_of_clients = companies(:first_firm).clients_of_firm.size
+    companies(:first_firm).clients_of_firm.find_or_initialize_by_name("name" => "Another Client")
+    assert_equal number_of_clients + 1, companies(:first_firm).clients_of_firm.size
+  end
+
+  def test_find_or_create_with_hash
+    post = authors(:david).posts.find_or_create_by_title(:title => 'Yet another post', :body => 'somebody')
+    assert_equal post, authors(:david).posts.find_or_create_by_title(:title => 'Yet another post', :body => 'somebody')
+    assert post.persisted?
+  end
+
+  def test_find_or_create_with_one_attribute_followed_by_hash
+    post = authors(:david).posts.find_or_create_by_title('Yet another post', :body => 'somebody')
+    assert_equal post, authors(:david).posts.find_or_create_by_title('Yet another post', :body => 'somebody')
+    assert post.persisted?
+  end
+
+  def test_find_or_create_should_work_with_block
+    post = authors(:david).posts.find_or_create_by_title('Yet another post') {|p| p.body = 'somebody'}
+    assert_equal post, authors(:david).posts.find_or_create_by_title('Yet another post') {|p| p.body = 'somebody'}
+    assert post.persisted?
+  end
+
   def test_deleting
     force_signal37_to_load_all_clients_of_firm
     companies(:first_firm).clients_of_firm.delete(companies(:first_firm).clients_of_firm.first)