title: Embedded hasMany attribute access gives "TypeError: Cannot call method 'hasOwnProperty' of undefined"
body: <p>Using:</p>
  
  <ul>
  <li>Ember <a href="https://github.com/emberjs/ember.js/commit/a5d45f66e1f71bb5eda417c688db0ea08b474903" rel="nofollow noreferrer">commit a5d45f66e1 from Jan 3, 2013)</a></li>
  <li>Ember-Data <a href="https://github.com/emberjs/data/commit/508479dee764c2e9926487131a5a4814cfda1bf6" rel="nofollow noreferrer">commit 508479dee7 from Jan 4, 2013</a></li>
  </ul>
  
  <p>Similar to <a href="https://stackoverflow.com/questions/14170370/unable-to-get-hasmany-association">this question ('Unable to get hasMany association')</a>, I am unable to access embedded hasMany records directly but can see them through the model's content attribute.</p>
  
  <p>For JSON:</p>
  
  <pre><code>{
     "ref_book_search":{
        "query":"har",
        "results":[
           {
              "publisher":{
                 "name":"Pangolin",
                 "created":"2012-09-10T18:38:27.259515",
                 "id":"3d2028e4fb91181e1a6e012313914f821",
                 "is_active":true,
                 "main_url":null,
                 "resource_uri":"/api/v1/ref_publisher/3d2028e4fb91181e1a6e012313914f821"
              },
              "genre":"romcom",
              "id":"cc671f00fc2711e1e41612313914f821",
              "resource_uri":"/api/v1/ref_book/cc671f00fc2711e1e41612313914f821",
              "title":"Harry Placeholder and the Goblet of PBR"
           },
           {
              "publisher":{
                 "name":"Hoof &amp; Mouth",
                 "created":"2012-10-10T14:31:27.259515",
                 "id":"3d200e9afb9811e1a27417383914f821",
                 "is_active":true,
                 "main_url":null,
                 "resource_uri":"/api/v1/ref_publisher/3d200e9afb9811e1a27417383914f821"
              },
              "genre":"horror",
              "id":"cc621f08fc2711e1b81612313914e821",
              "resource_uri":"/api/v1/ref_book/cc621f08fc2711e1b81612313914e821",
              "title":"Harvey Weinstein Holiday Cookbook"
           }
        ]
     }
  }
  </code></pre>
  
  <p>And app.js (note the map statements, which were the solution suggested in the prior question):</p>
  
  <pre><code>var App = Ember.Application.create();
  
  DS.RESTAdapter.configure("plurals", {"ref_book_search" : "ref_book_search"});
  
  App.store = DS.Store.create({
    revision: 11,
    adapter: DS.RESTAdapter.create({
      bulkCommits: false,
      namespace: "api/v1"
    })
  });
  
  DS.RESTAdapter.map('App.RefBookSearch', {
    primaryKey: 'query'
  });
  
  App.store.adapter.serializer.map('App.RefBookSearch', {
    results: {embeddded: 'load'}
  });
  
  App.store.adapter.serializer.map('App.RefBook', {
    publisher: {embeddded: 'load'}
  });
  
  App.RefPublisher = DS.Model.extend({
    name : DS.attr('string'),
    created : DS.attr('date'),
    isActive : DS.attr('boolean'),
    mainUrl : DS.attr('string')
  });
  
  App.RefBook = DS.Model.extend({
    publisher: DS.belongsTo('App.RefPublisher'),
    title : DS.attr('string'),
    genre : DS.attr('string')
  });
  
  App.RefBookSearch = DS.Model.extend({
    query: DS.attr('string'),
    results: DS.hasMany('App.RefBook')
  });
  
  App.Router.map(function(match) {
    match('/').to('query'),
    match('/query/:ref_book_search_id').to('query')
  });
  
  App.QueryController = Ember.Controller.extend({
    bookSearch: null,
    results: []
  });
  
  App.QueryRoute = Ember.Route.extend({
    setupControllers: function(controller, refBookSearch) {
      controller.set('bookSearch', refBookSearch)
      controller.set('results', refBookSearch.get('results').content)
    }
  })
  
  App.initialize();
  </code></pre>
  
  <p>Everything looks fine at first, just like other poster:</p>
  
  <pre><code>search = App.RefBookSearch.find('ha')
  search.get('query')
  // =&gt; "ha"
  results = search.get('results')
  results.get('firstObject') instanceof App.RefBook
  // =&gt; true
  </code></pre>
  
  <p>But then: </p>
  
  <pre><code>results.forEach(function(result) { console.log(result.get('title')) })
  // =&gt; TypeError: Cannot call method 'hasOwnProperty' of undefined
  </code></pre>
  
  <p>Accessing via content shows the data is there:</p>
  
  <pre><code>results.content.forEach(function(result) { console.log(result.title) })
  // =&gt; Harry Placeholder and the Goblet of PBR
  // =&gt; Harvey Weinstein Holiday Cookbook
  </code></pre>
  
  <p>Now if I try accessing directly again, I get a slightly different error:</p>
  
  <pre><code>results.forEach(function(result) { console.log(result.get('title')) })
  // =&gt; undefined x 2
  </code></pre>
  
  <p>This may or may not be related to <a href="https://github.com/emberjs/data/pull/568" rel="nofollow noreferrer">this bug</a> filed a few days ago. </p>
  
  <p>I feel like I've tried everything here; I hope I'm just missing something simple. Any pointers very much appreciated. Thanks.</p>