CORS issue with Rails 3 consuming mongodb rest api - ruby-on-rails-3

Question

I'm experiencing a cross-origin resource sharing (CORS) issue with my Rails 3 application consuming the mongodb simple rest api. I have some CoffeeScript/JavaScript which is trying to consume the mongodb simple rest api, however Chrome prevents it with the following console message:
XMLHttpRequest cannot load http://127.0.0.1:28017/my-db/my-collection/. Origin http://127.0.0.1:3000 is not allowed by Access-Control-Allow-Origin.
I've added the two controller methods from this blog post:
before_filter :cors_preflight_check
after_filter :cors_set_access_control_headers
def cors_set_access_control_headers
headers['Access-Control-Allow-Origin'] = '*'
headers['Access-Control-Allow-Methods'] = 'POST, GET, OPTIONS'
headers['Access-Control-Max-Age'] = '1728000'
end
def cors_preflight_check
if request.method == :options
headers['Access-Control-Allow-Origin'] = '*'
headers['Access-Control-Allow-Methods'] = 'POST, GET, OPTIONS'
headers['Access-Control-Allow-Headers'] = 'Content-Type, X-Requested-With, X-Prototype-Version'
headers['Access-Control-Max-Age'] = '1728000'
render text: '', content_type: 'text/plain'
end
end
I can see the headers are present for my Rails page. However, it still isn't working.
My best guess is that whatever web server which the mongodb simple rest api uses needs to include the headers, not my Rails app. Can anyone confirm or deny this?
I also read somewhere that I could use a proxy re-write rule in nginx. However, this is somewhat tedious, especially since I'm not running nginx for development, only on the production server.

Answer 1

Whatever headers you are setting in Rails have nothing to do with the headers sent by Chrome for the ajax request to MongoDB directly. You need to use JSONP to get around the CORS issues.
Start mongod with --rest and --jsonp and Mongod will be setup appropriately. Then make a JSONP request using jquery or whatever and it should work fine.