Ensure Model.scoped adds type conditions for STI models

activerecord/lib/active_record/named_scope.rb

@@ -28,6 +28,7 @@ def scoped(options = {}, &block)
         else
           if !scoped?(:find)
             relation = arel_table
+            relation = relation.where(type_condition) if finder_needs_type_condition?
           else
             relation = construct_finder_arel
             include_associations = scope(:find, :include)

activerecord/lib/active_record/relation.rb

@@ -49,19 +49,22 @@ def on(join)
     end
 
     def joins(join, join_type = nil)
-      join = case join
-        when String
-          @relation.join(join)
-        when Hash, Array, Symbol
-          if @klass.send(:array_of_strings?, join)
-            @relation.join(join.join(' '))
-          else
-            @relation.join(@klass.send(:build_association_joins, join))
-          end
+      return self if join.blank?
+
+      join_relation = case join
+      when String
+        @relation.join(join)
+      when Hash, Array, Symbol
+        if @klass.send(:array_of_strings?, join)
+          @relation.join(join.join(' '))
         else
-          @relation.join(join, join_type)
+          @relation.join(@klass.send(:build_association_joins, join))
+        end
+      else
+        @relation.join(join, join_type)
       end
-      create_new_relation(join)
+
+      create_new_relation(join_relation)
     end
 
     def where(*args)

activerecord/test/cases/finder_test.rb

@@ -291,7 +291,7 @@ def test_find_on_hash_conditions_with_hashed_table_name
   end
 
   def test_find_with_hash_conditions_on_joined_table
-    firms = Firm.all :joins => :account, :conditions => {:accounts => { :credit_limit => 50 }}
+    firms = Firm.joins(:account).where(:accounts => { :credit_limit => 50 })
     assert_equal 1, firms.size
     assert_equal companies(:first_firm), firms.first
   end