post_route.js

App.PostRoute = Em.Route.extend({
  model: function(params) {
    return Em.$.ajax({
      type: 'GET',
      url: App.API+'/post/'+ params.post_id,
      dataType: 'json',
      contentType: 'application/json',
      context: this
    }).then(function(json) {
      if (json.status.code === 200) {//API return status code with success or errors
        return App.Post.create(json.data[0]);
      } else {
        App.notification('Server is failing! Sorry! Try again later.', 'notification-error');
      }
    });
  },
  setupController: function(controller, model) {
    this.controllerFor('postIndex').set('content', model);
  }
});

posts_route.js

App.PostsIndexRoute = Em.Route.extend({
  model: function() {
    return Em.$.ajax({
      type: 'GET',
      url: App.API+'/posts',
      dataType: 'json',
      contentType: 'application/json',
      context: this
    }).then(function(json) {
      if (json.status.code === 200) {
        var posts = Em.A();

        json.data.forEach(function (post){
          posts.pushObject(App.Post.create(post));
        });
        return posts;
      } else {
        App.notification('Server is failing! Sorry! Try again later.', 'notification-error');
      }
    });
  }
});

pusher_callback

var pusher = new Pusher('APP_KEY');

var eventName = 'new-comment';
var callback = function(data) {
  var applicationRoute = App.__container__.lookup('route:application');
  Em.A(data).map(function(comment){
    applicationRoute.findModel( "post", comment.post_id );
    post.comments.push(App.Comment.create(comment));
  });
};
pusher.bind(eventName, callback);