Question

I have a User model in a Backbone application that makes an ajax request. In the error callback, I wish to set an error message to pass to the view. However, if I try do

this.set({errors: result.errors});

I’m told “this” doesn’t have a method set. In this case, I believe “this” is the ajax response object (rather than the User model which does have a set method)

Object {url: "/users.json", isLocal: false, global: true, type: "POST", contentType: "application/x-www-form-urlencoded; charset=UTF-8"…}

However, I also tried to do

  this.model.set({errors: result.errors});

but it said I can’t call “set” of undefined. I’m assuming it doesn’t make sense to say “this.model” from within the model, but, as mentioned above, if I just say “this,” it refers to the response object.

Is this the wrong way to go about it?

Answer 1

I am assuming you are doing something like this when you are saving your model

model.save({
  success: function() {},
  error: function() {
    this.set({ errors: result.errors });
  }
});

If that is the case, then you can change this.set to model.set, and everything will work.

However it doesn’t really make that much sense to be storing the error message as a model attribute.

The model will fire an event when its save call fails on the server (check out the backbone events catalogue).

Therefore if you have a view with an attached model, you can tell the view to listen to this error event.

var MyView = Backbone.View.extend({
  initialize: function() {
    // if your using backbone v0.9.10
    this.listenTo(this.model, 'error', this.handleModelError);
    // or for earlier versions
    this.model.on('error', this.handleModelError, this);
  },

  handleModelError: function(model, xhr, options) {
    // show an error message, or whatever
  }

});

var view = new MyView({ model: aModel });

// if the server returns an error, view.handleModelError will be called
aModel.save();