title: HasMany Relationship to Create Record - Why is undefined?
body: <p>I have an issue which relates to a "HasMany Relationship to Create Record" but I have looked and tried the answers that are already on stack overflow and they don't work. The issue is that the model is undefined. I have combined the QuestionsController and TopicController.</p>
  
  <p>This is the model for Topic:</p>
  
  <pre class="lang-js prettyprint-override"><code>App.Topic = DS.Model.extend({
    title: DS.attr('string'),
      questions: DS.hasMany('Question', {async: true}),
  });
  
  App.Topic.FIXTURES = [
   {
     id: 1,
     title: 'Early America',
      questions: [1,2]
   },
   {
     id: 2,
     title: 'American Revolution',
   },
   {
     id: 3,
     title: 'Modern America',
   }
  ];
  </code></pre>
  
  <p>This is the TopicsController:</p>
  
  <pre><code>App.TopicsController = Ember.ArrayController.extend({ 
  
      actions: {
          createTopic: function () {
              var Topic = this.store.createRecord('Topic', {
                  title: 'Untitled Topic'
              });
              /* Topic.get(questions.find(1)... */
              Topic.save();
  
              this.set('newTitle', '');
          },
      }
  });
  </code></pre>
  
  <p>This is the TopicController:</p>
  
  <pre><code>App.TopicController = Ember.ObjectController.extend({
      isEditing: false,
      actions: {
          editTopic: function () {
              this.set('isEditing', true);
          },
          acceptChanges: function () {
              this.set('isEditing', false);
          },
          removeTopic: function () {
              var topic = this.get('model');
  
              topic.deleteRecord();
              topic.save();
          },
          createQuestion: function () {
              var question = this.get('store').createRecord('Question', {
                  title: 'Untitled Question',
                  topic: this.get('model'),
              });
              question.save();
          }
      }   
  });
  </code></pre>
  
  <p>This is the model for question:</p>
  
  <pre><code>App.Question = DS.Model.extend({
      title: DS.attr('string'),
      topic: DS.belongsTo('Topic', {async: true}),
  });
  
  App.Question.FIXTURES = [
   {
     id: 1,
     title: 'What continent did Colombus find?',
     topic: 1,
   },
   {
     id: 2,
     title: 'Other question',
   },
  ];
  </code></pre>
  
  <p>And this is the QuestionController:</p>
  
  <pre><code>App.QuestionController = Ember.ObjectController.extend({ 
     isEditing: false,
      actions: {
          editQuestion: function () {
              this.set('isEditing', true);
          },
          acceptChanges: function () {
              this.set('isEditing', false);
          },
          removeQuestion: function () {
              console.log(this);
                          console.log("hello");
                          var question = this.get('model');
  
                          question.deleteRecord();
                          question.save();
          }
      }
  });
  </code></pre>
  
  <p>This is where all the files are stored: <a href="https://github.com/Glorious-Game-Design-ASL/MapQuizGame/tree/master/quiz_creator" rel="nofollow">https://github.com/Glorious-Game-Design-ASL/MapQuizGame/tree/master/quiz_creator</a></p>