Question

Getting my brain wrapped around emberjs. Trying to create a controller that loads objects from a webservice call that returns a JSON array:

(Note that this is javascript generated from coffeescript)

MTM.Trade.controller = Ember.ArrayController.create({
  loadAll: function() {
    var self;
    self = this;
    this.set('content', []); /* fails with or without this line*/
    return $.getJSON('http://localhost:8080/webservice/trades', function(data) {
      var jsonTrade, trade, _i, _len;
      console.log("Length = " + data.length);
      for (_i = 0, _len = data.length; _i < _len; _i++) {
        jsonTrade = data[_i];
        trade = MTM.Trade.create(jsonTrade);
        self.pushObject(trade);
      }
      console.log("Everything pushed");
    });
  }
});

Upon calling MTM.Trade.controller.loadAll(), it’s clear that the loop is being called for each object. However my controller never changes.. running console.log MTM.Trade.controller.get('content') returns a blank array.

I know that ember-rest and ember-data exist, but for now I’m rolling-my-own to learn how to do these things myself, and the will migrate to those frameworks later.

UPDATE

Thanks to this article I did get the answer to my question.. I need to init my array as such:

MTM.Trade.controller = Ember.ArrayController.create({

  init: function() {
    this._super();
    return this.set('content', Ember.A());
  },

loadAll: function() {
    ...

So now my question is, why? Intuitively shouldn’t the ArrayController initializer take care of this? Perhaps this is not the way an ArrayController is expected to be used?

Answer 1

Before your update, I put a comment, where I told you to initialize the content at creation time (so in the hash of the create).

MTM.Trade.controller = Ember.ArrayController.create({
    content: [],
    //...
});

But then I saw that you were setting content to [] in the loadAll function. So I was thinking that initialization was unnecessary.

When looking closest to ArrayController, it’s just an extension of the ArrayProxy mixin, (ie: kinds of interface), so when creating an instance of an ArrayController, you must define the content property.