Allow association redefinition in subclasses. Closes #9346.

git-svn-id: http://svn-commit.rubyonrails.org/rails/trunk@8046 5ecf4fe2-1ee6-0310-87b1-e25e094e27de

4 files changed, 89 insertions, 2 deletions

diff --git a/activerecord/CHANGELOG b/activerecord/CHANGELOG
index 6847755e6e..1875eda3ba 100644
--- a/activerecord/CHANGELOG
+++ b/activerecord/CHANGELOG
@@ -1,5 +1,7 @@
 *SVN*
 
+* Allow association redefinition in subclasses.  #9346 [wildchild]
+
 * Fix has_many :through delete with custom foreign keys.  #6466 [naffis]
 
 * Foxy fixtures, from rathole (http://svn.geeksomnia.com/rathole/trunk/README)
diff --git a/activerecord/lib/active_record/associations.rb b/activerecord/lib/active_record/associations.rb
index e542e8d85a..654b24d71c 100755
--- a/activerecord/lib/active_record/associations.rb
+++ b/activerecord/lib/active_record/associations.rb
@@ -955,7 +955,7 @@ module ActiveRecord
         # Don't use a before_destroy callback since users' before_destroy
         # callbacks will be executed after the association is wiped out.
         old_method = "destroy_without_habtm_shim_for_#{reflection.name}"
-        class_eval <<-end_eval
+        class_eval <<-end_eval unless method_defined?(old_method)
           alias_method :#{old_method}, :destroy_without_callbacks
           def destroy_without_callbacks
             #{reflection.name}.clear
@@ -1351,7 +1351,9 @@ module ActiveRecord
             defined_callbacks = options[callback_name.to_sym]
             if options.has_key?(callback_name.to_sym)
               class_inheritable_reader full_callback_name.to_sym
-              write_inheritable_array(full_callback_name.to_sym, [defined_callbacks].flatten)
+              write_inheritable_attribute(full_callback_name.to_sym, [defined_callbacks].flatten)
+            else
+              write_inheritable_attribute(full_callback_name.to_sym, [])
             end
           end
         end
diff --git a/activerecord/test/aggregations_test.rb b/activerecord/test/aggregations_test.rb
index 89927e5044..299e0484e3 100644
--- a/activerecord/test/aggregations_test.rb
+++ b/activerecord/test/aggregations_test.rb
@@ -108,3 +108,21 @@ class AggregationsTest < Test::Unit::TestCase
     assert_equal nil, customers(:david).gps_location
   end
 end
+
+class OverridingAggregationsTest < Test::Unit::TestCase
+  class Name; end
+  class DifferentName; end
+
+  class Person   < ActiveRecord::Base
+    composed_of :composed_of, :mapping => %w(person_first_name first_name)
+  end
+
+  class DifferentPerson < Person
+    composed_of :composed_of, :class_name => 'DifferentName', :mapping => %w(different_person_first_name first_name)
+  end
+
+  def test_composed_of_aggregation_redefinition_reflections_should_differ_and_not_inherited
+    assert_not_equal Person.reflect_on_aggregation(:composed_of),
+                     DifferentPerson.reflect_on_aggregation(:composed_of)
+  end
+end
diff --git a/activerecord/test/associations_test.rb b/activerecord/test/associations_test.rb
index 121a8c5ac4..1fe8d2a417 100755
--- a/activerecord/test/associations_test.rb
+++ b/activerecord/test/associations_test.rb
@@ -1932,3 +1932,68 @@ class HasAndBelongsToManyAssociationsTest < Test::Unit::TestCase
     end
   end
 end
+
+
+class OverridingAssociationsTest < Test::Unit::TestCase
+  class Person < ActiveRecord::Base; end
+  class DifferentPerson < ActiveRecord::Base; end
+
+  class PeopleList < ActiveRecord::Base
+    has_and_belongs_to_many :has_and_belongs_to_many, :before_add => :enlist
+    has_many :has_many, :before_add => :enlist
+    belongs_to :belongs_to
+    has_one :has_one
+  end
+
+  class DifferentPeopleList < PeopleList
+    # Different association with the same name, callbacks should be omitted here.
+    has_and_belongs_to_many :has_and_belongs_to_many, :class_name => 'DifferentPerson'
+    has_many :has_many, :class_name => 'DifferentPerson'
+    belongs_to :belongs_to, :class_name => 'DifferentPerson'
+    has_one :has_one, :class_name => 'DifferentPerson'
+  end
+
+  def test_habtm_association_redefinition_callbacks_should_differ_and_not_inherited
+    # redeclared association on AR descendant should not inherit callbacks from superclass
+    callbacks = PeopleList.read_inheritable_attribute(:before_add_for_has_and_belongs_to_many)
+    assert_equal([:enlist], callbacks)
+    callbacks = DifferentPeopleList.read_inheritable_attribute(:before_add_for_has_and_belongs_to_many)
+    assert_equal([], callbacks)
+  end
+
+  def test_has_many_association_redefinition_callbacks_should_differ_and_not_inherited
+    # redeclared association on AR descendant should not inherit callbacks from superclass
+    callbacks = PeopleList.read_inheritable_attribute(:before_add_for_has_many)
+    assert_equal([:enlist], callbacks)
+    callbacks = DifferentPeopleList.read_inheritable_attribute(:before_add_for_has_many)
+    assert_equal([], callbacks)
+  end
+
+  def test_habtm_association_redefinition_reflections_should_differ_and_not_inherited
+    assert_not_equal(
+      PeopleList.reflect_on_association(:has_and_belongs_to_many),
+      DifferentPeopleList.reflect_on_association(:has_and_belongs_to_many)
+    )
+  end
+
+  def test_has_many_association_redefinition_reflections_should_differ_and_not_inherited
+    assert_not_equal(
+      PeopleList.reflect_on_association(:has_many),
+      DifferentPeopleList.reflect_on_association(:has_many)
+    )
+  end
+
+  def test_belongs_to_association_redefinition_reflections_should_differ_and_not_inherited
+    assert_not_equal(
+      PeopleList.reflect_on_association(:belongs_to),
+      DifferentPeopleList.reflect_on_association(:belongs_to)
+    )
+  end
+
+  def test_has_one_association_redefinition_reflections_should_differ_and_not_inherited
+    assert_not_equal(
+      PeopleList.reflect_on_association(:has_one),
+      DifferentPeopleList.reflect_on_association(:has_one)
+    )
+  end
+end