Rails 5 api controller not receiving params sent by frontend app [duplicate] - ruby

Question

I seem to be running into some issues making a GET request to an API endpoint. I know rails has some security going on behind the scenes. I'm using React-Rails and in my componentDidMount to make an ajax call to an API endpoint. I am passing in a X-Auth-Token in my headers too.
My console error:
XMLHttpRequest cannot load "/api/end/point..." Response to preflight request doesn't pass access control check: No 'Access-Control-Allow-Origin' header is present on the requested resource. Origin 'http://localhost:3000' is therefore not allowed access. The response had HTTP status code 401.
My ajax call is looking like
$.ajax({ url: "my/api/endpoint...", headers: {"X-Auth-Token": "My API token..."},
success: (response) => { console.log(response); } })

Answer 1

Because your frontend will do requests from any origin (any client), you have to enable CORS from any origin. Try
# config/initializers/cors.rb
Rails.application.config.middleware.insert_before 0, Rack::Cors do
allow do
origins '*'
resource '*',
headers: :any,
methods: [:get, :post, :put, :patch, :delete, :options, :head]
end
end
I use this in a rails 5 api application. Before rails 5 add rack-cors gem to your Gemfile. Anyway, restart your server.
rails 3/4
# config/application.rb
module YourApp
class Application < Rails::Application
config.middleware.insert_before 0, "Rack::Cors" do
allow do
origins '*'
resource '*', :headers => :any, :methods => [:get, :post, :options]
end
end
end
end