Move constructing polymorphic type to `join_scope` in `Reflection`

1 files changed, 7 insertions, 4 deletions

diff --git a/activerecord/lib/active_record/reflection.rb b/activerecord/lib/active_record/reflection.rb
index c6aa2ed720..4e3359bb4e 100644
--- a/activerecord/lib/active_record/reflection.rb
+++ b/activerecord/lib/active_record/reflection.rb
@@ -185,12 +185,16 @@ module ActiveRecord
       end
       deprecate :scope_chain
 
-      def join_scope(table)
+      def join_scope(table, foreign_klass)
         predicate_builder = predicate_builder(table)
         scope_chain_items = join_scopes(table, predicate_builder)
         klass_scope       = klass_join_scope(table, predicate_builder)
 
-        scope_chain_items.inject(klass_scope || scope_chain_items.shift, &:merge!)
+        if type
+          klass_scope.where!(type => foreign_klass.base_class.name)
+        end
+
+        scope_chain_items.inject(klass_scope, &:merge!)
       end
 
       def join_scopes(table, predicate_builder) # :nodoc:
@@ -207,8 +211,7 @@ module ActiveRecord
             scope.joins_values = scope.left_outer_joins_values = [].freeze
           }
         else
-          relation = build_scope(table, predicate_builder)
-          klass.send(:build_default_scope, relation)
+          klass.default_scoped(build_scope(table, predicate_builder))
         end
       end