Add support for belongs_to to has_many inversing.

activerecord/CHANGELOG.md

@@ -1,3 +1,7 @@
+*   Add support for `belongs_to` to `has_many` inversing.
+
+    *Gannon McGibbon*
+
 *   Allow length configuration for `has_secure_token` method. The minimum length
     is set at 24 characters.
 

activerecord/lib/active_record/associations/belongs_to_association.rb

@@ -108,11 +108,8 @@ module ActiveRecord
           owner._read_attribute(reflection.foreign_key)
         end
 
-        # NOTE - for now, we're only supporting inverse setting from belongs_to back onto
-        # has_one associations.
         def invertible_for?(record)
-          inverse = inverse_reflection_for(record)
+          inverse_reflection_for(record)
-          inverse && inverse.has_one?
         end
 
         def stale_state

activerecord/lib/active_record/associations/collection_association.rb

@@ -285,6 +285,15 @@ module ActiveRecord
         replace_on_target(record, index, skip_callbacks, &block)
       end
 
+      def target=(record)
+        case record
+        when Array
+          super
+        else
+          add_to_target(record)
+        end
+      end
+
       def scope
         scope = super
         scope.none! if null_scope?

activerecord/test/cases/associations/inverse_associations_test.rb

@@ -607,7 +607,7 @@ class InverseBelongsToTests < ActiveRecord::TestCase
     assert_equal f.description, m.face.description, "Description of face should be the same after changes to newly-created-parent-owned instance"
   end
 
-  def test_should_not_try_to_set_inverse_instances_when_the_inverse_is_a_has_many
+  def test_should_try_to_set_inverse_instances_when_the_inverse_is_a_has_many
     i = interests(:trainspotting)
     m = i.man
     assert_not_nil m.interests
@@ -615,9 +615,9 @@ class InverseBelongsToTests < ActiveRecord::TestCase
     assert_not_nil iz
     assert_equal i.topic, iz.topic, "Interest topics should be the same before changes to child"
     i.topic = "Eating cheese with a spoon"
-    assert_not_equal i.topic, iz.topic, "Interest topics should not be the same after changes to child"
+    assert_equal i.topic, iz.topic, "Interest topics should be the same after changes to child"
     iz.topic = "Cow tipping"
-    assert_not_equal i.topic, iz.topic, "Interest topics should not be the same after changes to parent-owned instance"
+    assert_equal i.topic, iz.topic, "Interest topics should be the same after changes to parent-owned instance"
   end
 
   def test_child_instance_should_be_shared_with_replaced_via_accessor_parent
@@ -704,7 +704,7 @@ class InversePolymorphicBelongsToTests < ActiveRecord::TestCase
     assert_equal old_inversed_man.object_id, new_inversed_man.object_id
   end
 
-  def test_should_not_try_to_set_inverse_instances_when_the_inverse_is_a_has_many
+  def test_should_try_to_set_inverse_instances_when_the_inverse_is_a_has_many
     i = interests(:llama_wrangling)
     m = i.polymorphic_man
     assert_not_nil m.polymorphic_interests
@@ -712,9 +712,9 @@ class InversePolymorphicBelongsToTests < ActiveRecord::TestCase
     assert_not_nil iz
     assert_equal i.topic, iz.topic, "Interest topics should be the same before changes to child"
     i.topic = "Eating cheese with a spoon"
-    assert_not_equal i.topic, iz.topic, "Interest topics should not be the same after changes to child"
+    assert_equal i.topic, iz.topic, "Interest topics should be the same after changes to child"
     iz.topic = "Cow tipping"
-    assert_not_equal i.topic, iz.topic, "Interest topics should not be the same after changes to parent-owned instance"
+    assert_equal i.topic, iz.topic, "Interest topics should be the same after changes to parent-owned instance"
   end
 
   def test_trying_to_access_inverses_that_dont_exist_shouldnt_raise_an_error