Binding to relationship property

Asked By: Anonymous

I’m trying to bind an attribute of a DS.belongsTo relationship like this:

App.User = DS.Model.extend({
  name: DS.attr('string')
});

App.Post = DS.Model.extend({
  text: DS.attr('string'),
  user: DS.belongsTo('App.User'),

  userNameBinding: 'user.name'
});

I know this example is a little bit stupid, but the idea is here.

Unfortunately, it does not work (in model.js, at this line):

Uncaught TypeError: Cannot call method ‘send’ of null

I also tried to use Ember.Binding.oneWay, but it does not work either. My current workaround is pretty ugly:

App.Post = DS.Model.extend({
  // code omitted

  userName: function() {
    return this.get('user.name');
  }.property('user.name')
});

You can test it in this JSFiddle.

Ember version used:

• ember-data on master
• ember v1.0.0-pre.2-311-g668783a

Solution

Answered By: Anonymous

There appears to be a bug with bindings to properties that rely on state set up in init. I have filed a bug on the Ember issue tracker.

For a less ugly solution, you can use Ember.computed.alias:

App.Post = DS.Model.extend({
  text: DS.attr('string'),
  user: DS.belongsTo('App.User'),

  userName: Ember.computed.alias('user.name')
});

I have a working example in this JSBin.