CORS Rails 4+

application.rb

config.middleware.insert_before 0, "Rack::Cors", debug: true, logger: ->{Rails.logger} do
      allow do
        origins 'localhost:3000'
        resource %r{/users\/?\d*},
          :headers => ['Origin', 'Accept', 'Content-Type','Token'],
          :methods => [:get, :put, :delete],
          :max_age => 0
      end
    end

curl_commands.md

-I means to show only headers

-H header to include in request

##Sending origin header:

curl -H "Origin: http://localhost:3000" -I http://localhost:3001/users

##Sending preflight options

curl -X OPTIONS -I http://localhost:3001/users -H 'Origin: http://localhost:3000' -H 'Access-Control-Request-Method: GET' -H 'Access-Control-Request-Headers: token'

curl
-H "Accept: application/json"
-H "Content-type: application/json"
-X POST
-d '{"name":"New User"}'
http://localhost:3001/users.json

notes.md

Need to set resource as a regular expression in order for OPTIONS to work without having to specify extra routes and controller.

Tested in Rails 4.0.13

Useful links:

http://blog.carbonfive.com/2012/02/27/supporting-cross-domain-ajax-in-rails-using-jsonp-and-cors/

http://jbilbo.com/blog/2015/05/19/testing-cors-with-rspec/