How to get the id when I create a save a new model
===

In my `Marionette.CompositeView` it will be possible to create a new model making a put request to the server(1).        
The put request is ok, but when I add the new model to the collection, the new model misses the id which is created by the server.     
How should I fix this issue? 

Should      
1) the POST request send the id to the client or   
2) I have to make another request from the client to get the id?

---

(1)

    return Marionette.CompositeView.extend({

	    submitForm: function (event) {
                this.textAreaElement = this.$el.find('[data-tid="announcement"]');
                this.messageModel = new MessageModel();
                this.messageModel.save({
                    message: this.textAreaElement.val()
                }, {
                    success: this.onSuccess,
                    error: this.onError
                });
       },

        onSuccess: function () {
            this.collection.add(this.messageModel); // I need to get also the id of the following model
                                                    // which is created by the server
        }

    });

