Update Country code field upon selecting Country field using AJAX

application.js

 $(document).ready(function(){
$("#id_country_code").change(function(){
        var option = $(this).val();
        $.ajax({
          type: "GET",
          url: "/models/get",
          data:{
            key: option
          },
          success: function(response){
            if(response.phone)
              $("#phone").val(response.phone); 
          }
        })
      });


    });

model_get.rb

@c = params[:key]
    @c = ISO3166::Country.new(@c)
    @c = @c.country_code
    @c = "+#{@c}"

    render json: {:phone => @c}

routes.rb

resources :models do
      collection do
        get 'get'
      end
    end