No 'Access-Control-Allow-Origin' header is present on the requested resource

I’m trying to implement google places api in my rails app for finding restaurants near my location.

This is the error I’m getting when trying to use the function that is fetching the data from the ajax request:

XMLHttpRequest cannot load . 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.

I’ve added this snippet into my config/application.rb file:

    config.middleware.insert_before 0, "Rack::Cors" do
          allow do
            origins '*'
            resource '*', :headers => :any, :methods => [:get, :post, :options]
          end
        end

This is the ajax request from my view (coffeescript):

        $.ajax
          url: url
          dataType: "json"
          type: "GET"

and I’ve noticed that my request headers remain unchanged.

(Access-Control-Allow-Origin is not added to request headers)

    Request URL: (not relevant)
    Request Method:OPTIONS
    Status Code:200 
    Remote Address: (not relevant)

    Response Headers
    alt-svc:quic=":443"; ma=2592000; v="33,32,31,30,29,28,27,26,25"
    alternate-protocol:443:quic
    cache-control:public, max-age=300
    content-encoding:gzip
    content-length:538
    content-type:application/json; charset=UTF-8
    date:Mon, 16 May 2016 12:59:48 GMT
    expires:Mon, 16 May 2016 13:04:48 GMT
    server:pablo
    status:200
    vary:Accept-Language
    x-frame-options:SAMEORIGIN
    x-xss-protection:1; mode=block

    Request Headers
    Provisional headers are shown
    Access-Control-Request-Headers:accept, x-csrf-token
    Access-Control-Request-Method:GET
    Origin:http://localhost:3000
    Referer:http://localhost:3000/restil/new?
    User-Agent:Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/50.0.2661.102 Safari/537.36

    Query String Parameters
    view source
    view URL encoded
    location:( not relevant)
    radius:5000
    type:restraunt
    key: (not relevant)

jsonp is not an option because it’s not supported by places api

Tried everything that’s written in these threads:

• https://github.com/cyu/rack-cors/issues/33
• http://stackoverflow.com/questions/18538549/cant-get-rack-cors-working-in-rails-application (config.middleware.insert 0, Rack::Cors do)
• https://demisx.github.io/rails-api/2014/02/18/configure-accept-headers-cors.html
• http://stackoverflow.com/questions/36406869/add-custom-response-header-with-rack-cors-and-grape (using :expose key)

[bparanj]

This works:

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

This does not work:

Rails.application.config.middleware.insert_before 0, Rack::Cors do
  allow do
    origins 'http://localhost:3000'

    resource '*',
      headers: :any,
      methods: [:get, :post, :put, :patch, :delete, :options, :head]
  end
end

This also does not work:

Rails.application.config.middleware.insert_before 0, Rack::Cors do
  allow do
    origins 'localhost:3000', '127.0.0.1:3000'

    resource '*',
      headers: :any,
      methods: [:get, :post, :put, :patch, :delete, :options, :head]
  end
end

Adding:

  match '*path', via: [:options], to: lambda {|_| [204, { 'Content-Type' => 'text/plain' }]}

to routes does not help.

[asux]

Also tried all solutions and gem simply not works!