Ensure content type gets reset after render_to_string [#1182 state:resolved]

actionpack/lib/action_controller/base.rb

@@ -933,6 +933,7 @@ def render(options = nil, extra_options = {}, &block) #:doc:
       def render_to_string(options = nil, &block) #:doc:
         render(options, &block)
       ensure
+        response.content_type = nil
         erase_render_results
         reset_variables_added_to_assigns
       end

actionpack/test/controller/render_test.rb

@@ -154,6 +154,10 @@ def render_symbol_json
     render :json => {:hello => 'world'}.to_json
   end
 
+  def render_json_with_render_to_string
+    render :json => {:hello => render_to_string(:partial => 'partial')}
+  end
+
   def render_custom_code
     render :text => "hello world", :status => 404
   end
@@ -772,6 +776,12 @@ def test_render_symbol_json
     assert_equal 'application/json', @response.content_type
   end
 
+  def test_render_json_with_render_to_string
+    get :render_json_with_render_to_string
+    assert_equal '{"hello": "partial html"}', @response.body
+    assert_equal 'application/json', @response.content_type
+  end
+
   def test_render_custom_code
     get :render_custom_code
     assert_response 404