使用AJAX从Ruby on Rails服务器获取JSON内容

Question

I have some experience with RoR, although, I'm kind of a newbie in AJAX matters. My goal is to have a HTML5 + JavaScript client and a Ruby on Rails server running in different machines (eventually).

What I want is the JavaScript client to get contents from the server in JSON format, to be parsed afterwards. I already tried a bunch of things, like adding a "responseType", etc, but non of them worked.

My current JavaScript file is like this:

$(document).ready(function() {
      var xmlhttp = new XMLHttpRequest();
      xmlhttp.open("GET", "http://localhost:3000/contents", true);
      xmlhttp.send();

      alert(xmlhttp.responseText);
});

And my RoR app has a path "/contents" that calls the index function of contents_controller.rb, that is like this:

def index
    @contents = Content.all.order('created_at DESC')

    respond_to do |format|
        format.html # index.html.erb
        format.json { render json: @contents }
    end
end

Is AJAX even the correct way to do this? I'm a bit lost.

Thanks a lot!

Answer 1

With jQuery, you can do it like this.

$.ajax({
  url: '/contents',
  type: 'GET',
  dataType: 'json',
  beforeSend: function (xhr) {
      xhr.setRequestHeader('X-CSRF-Token', $('meta[name="csrf-token"]').attr('content'));
  },
  success: function(data){/* do something meaningful with data */},
  error: function(xhr, status, response) {/* your error callback */}
});

Your format.json shall handle your responses.

Answer 2

You can simply call /contents.json (add .json with every url to get output fron json template) or Set your default format as json if you never need html view. For that ...

You can modify your routes.rb files to specify the default format.

routes.rb

resources :contents, defaults: {format: :json}