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put :update in json format should return '{}' in real-life and not only in tests

#5975

There is a bug in jQuery 1.4.4 which causes an succesful ajax update to a resource to trigger 'ajax:failure' events instead of 'ajax:success'.

The reason for this is, that the server answers with status 200 and a nearly empty body, it contains 1 whitespace. This causes jQuery to choke on the parseJSON. And so the wrong ajax callbacks are triggered.

This one is easy to reproduce:

 #generate a new rails project
 $ rails new ujs_test && cd ujs_test
 # add the line 'gem 'jquery-rails' to your Gemfile
 $ bundle install
 $ rails g jquery:install
 $ rails g scaffold folder name:string

In the 'app/views/folders/_form.html.erb' change the first line to:

<%= form_for(@folder, :remote => true, :html => {'data-type' => 'json' }) do |f| %>

Be sure to use just responders:

class FoldersController < ApplicationController
respond_to :html, :json

def index
@folders = Folder.all
respond_with(@folders)
end

def edit
@folder = Folder.find(params[:id])
respond_with(@folder)
end

def new
@folder = Folder.new
respond_with(@folder)
end

def create
@folder = Folder.create(params[:folder])
respond_with(@folder)
end

def update
@folder = Folder.find(params[:id]).update_attributes(params[:folder])
respond_with(@folder)
end
end

As a debug/logger you can use this in your application.js

  // Place your application-specific JavaScript functions and classes here
  // This file is automatically included by javascript_include_tag :defaults
  $(function(){
      $('form[data-remote]').bind('ajax:success', function(data, status, xhr){
          console.log("*** ajax:success ***");
          console.dir(data);
          console.dir(status);
          console.log("*** END: ajax:success ***");
      });

      $('form[data-remote]').bind('ajax:failure', function(xhr, status, error){
          console.log("+++ ajax:failure +++");
          console.dir(xhr);
          console.dir(status);
          console.dir(error);
          console.log("+++ END: ajax:failure +++");
      });
  });

When you go to http://localhost/folders/1/edit (besure to have one created already).

Doing an edit and hitting update will trigger an 'ajax:failure' event although the response status is 200.

Reported by Christiaan Van den Poel · November 15th, 2010 @ 01:51 PM

Activity

Neeraj Singh
- Assigned user set to Neeraj Singh
- Importance changed from to Low
I'll take a look.

November 15th, 2010 @ 02:10 PM
Christiaan Van den Poel
- Assigned user cleared.
The bug was rejected by the jquery team http://bugs.jquery.com/ticket/7521

They say the string with whitespaces is not valid json, so it's in the rails code where the whitespaces should be removed from the response, no?

November 15th, 2010 @ 02:11 PM
Christiaan Van den Poel
In the file 'actionpack/lib/action_controller/metal/responder.rb' on line 167
https://github.com/rails/rails/blob/master/actionpack/lib/action_co...

The code is that for a successful update the response is
```
head :ok
```
In the file 'actionpack/lib/action_controller/metal/head.rb' on line 29
https://github.com/rails/rails/blob/master/actionpack/lib/action_co...

There is code that set the response body to a string with one whitespace, which is, according the jQuery team non valid when you return json.
```
 self.response_body = " "
```
I can imagine there is a historic reason to return one whitespace in case of a head response, but I also follow the jQuery team when they state that in case of a JSON response this string/response is invalid.
November 15th, 2010 @ 02:24 PM
Christiaan Van den Poel
- Assigned user set to Neeraj Singh
Seems during my comment edit I've removed the who's responsible?

November 15th, 2010 @ 02:25 PM

Christiaan Van den Poel

When I look at the rails code there is a test for returning '{}' when a put request is made in json format.

https://github.com/rails/rails/blob/master/actionpack/test/controll...

But when I use it in my application and browser, I get " " which is invalid json.

The thing is also: the accepts request header is:

Chrome 7: application/json, text/javascript, /; q=0.01
FF3: application/json, text/javascript, /; q=0.01

So when I write a new test:

def test_using_resource_for_put_with_json_yields_ok_on_success_2
   Customer.any_instance.stubs(:to_json).returns('{"name": "David"}')
   @request.accept = "application/json,text/javascript,*/*;q=0.01"
   put :using_resource
   assert_equal "application/json", @response.content_type
   assert_equal 200, @response.status
   assert_equal "{}", @response.body
end

this fails (exception):

NoMethodError: undefined method `hash_for_customer_url' for #<Module:0xb6936fb4>
/var/projects/github/rails@github/actionpack/lib/action_dispatch/routing/polymorphic_routes.rb:135:in `__send__'
/var/projects/github/rails@github/actionpack/lib/action_dispatch/routing/polymorphic_routes.rb:135:in `polymorphic_url'
/var/projects/github/rails@github/actionpack/lib/action_dispatch/routing/url_for.rb:138:in `url_for'
/var/projects/github/rails@github/actionpack/lib/action_controller/metal/redirecting.rb:93:in `_compute_redirect_to_location'
/var/projects/github/rails@github/actionpack/lib/action_controller/metal/redirecting.rb:63:in `redirect_to'
....

So then I write the test like this:

     def test_using_resource_for_put_with_json_yields_ok_on_success_2
    with_test_route_set do
    Customer.any_instance.stubs(:to_json).returns('{"name": "David"}')
        @request.accept = "application/json,text/javascript,*/*;q=0.01"
        put :using_resource
        assert_equal "application/json", @response.content_type
        assert_equal 200, @response.status
        assert_equal "{}", @response.body
    end
  end

The test fails (real test fail):

1) Failure:
test_using_resource_for_put_with_json_yields_ok_on_success_2(RespondWithControllerTest)
[controller/mime_responds_test.rb:742:in `test_using_resource_for_put_with_json_yields_ok_on_success_2'
 controller/mime_responds_test.rb:932:in `with_test_route_set'
 /var/projects/github/rails@github/actionpack/lib/action_dispatch/testing/assertions/routing.rb:164:in `with_routing'
 controller/mime_responds_test.rb:924:in `with_test_route_set'
 controller/mime_responds_test.rb:738:in `test_using_resource_for_put_with_json_yields_ok_on_success_2'
 /var/projects/github/rails@github/activesupport/lib/active_support/testing/setup_and_teardown.rb:67:in `__send__'
 /var/projects/github/rails@github/activesupport/lib/active_support/testing/setup_and_teardown.rb:67:in `run'
 /var/projects/github/rails@github/activesupport/lib/active_support/callbacks.rb:428:in `_run_setup_callbacks'
 /var/projects/github/rails@github/activesupport/lib/active_support/testing/setup_and_teardown.rb:65:in `run']:
 <"application/json"> expected but was
 <"text/html">.

So I'm testing with a reallife situation and the test fails?

Perhaps I'm not getting all this rails code and am I doing it wrong, perhaps someone can help out here.

November 15th, 2010 @ 03:42 PM

Christiaan Van den Poel
- Title changed from latest jquery (1.4.4) has a bug in its parseJSON that has an effect on jquery-ujs and its callbacks to put :update in json format should return '{}' in real-life and not only in tests
November 15th, 2010 @ 03:49 PM
Neeraj Singh
I followed your instruction and I am getting {} as the response.

November 15th, 2010 @ 05:16 PM
Neeraj Singh
I tested on rails edge.

November 15th, 2010 @ 05:17 PM
Christiaan Van den Poel
indeed, it look likes it is fixed in edge since 3.0.1.

My mistake...

Thx for checking
- responder.diff 2.75 KB
November 15th, 2010 @ 05:39 PM
Neeraj Singh
- State changed from new to resolved
November 19th, 2010 @ 04:45 PM