Ajax响应为空

I have an AJAX call that talks to my Rails controller, the AJAX is okay but the callback contains no data.

My AJAX call:

$.ajax({
    url: '/get_progress/:' + this.props.myfile,
    type: "GET",
    dataType: "text",
    success: function(data) {
        console.log(data);
    }.bind(this),
    error: function(data) {
        console.log("Error");
    }.bind(this)
});

My rails controller method:

def get_progress
    a = Rails.configuration.progress
    render :text => a
end

My routes:

get '/get_progress/:id' => 'myfiles#get_progress'

My AJAX Success callback has no data in it, why is my a value not passed back?

Your url is incorrect, the :id is meant to just be the value of the ID:

$.ajax({
    url: '/get_progress/' + this.props.myfile,
    type: "GET",
    dataType: "text",
    success: function(data) {
        console.log(data);
    },
    error: function(data) {
        console.log("Error");
    }
});