title: _.bindAll(this) and Uncaught TypeError: Cannot read property 'idAttribute' of undefined in backbone-relation.js
body: <p>I have two models (User and Task) which are instances of <code>Backbone.RelationalModel</code>.    </p>
  
  <p>The relation about these two models is the following:</p>
  
  <pre><code>// Task model
  
      var Task = Backbone.RelationalModel.extend({
  
          relations: [
              {
                  type: 'HasOne',
                  key: 'user',
                  relatedModel: User
              }
          ],
  
          urlRoot: 'someUrl'
  
      });
  </code></pre>
  
  <p>Then I have one collection which code looks like this:</p>
  
  <pre><code>var FollowerCollection = Backbone.Collection.extend({
      initialize: function () {
           _.bindAll(this);
      }
      model: User
  });
  
  
  var User = Backbone.RelationalModel.extend({
  
  });
  </code></pre>
  
  <hr>
  
  <p>When I make a fetch on FollowerCollection I get the following error:    </p>
  
  <pre><code> Uncaught TypeError: Cannot read property 'idAttribute' of undefined
  </code></pre>
  
  <p>on the line 1565 of backbone-relation.js of <code>backbone-relation version 0.5.0</code></p>
  
  <hr>
  
  <p>Here a piece of code of backbone-relation.js</p>
  
  <pre><code>if ( !( model instanceof Backbone.Model ) ) {
      // Try to find 'model' in Backbone.store. If it already exists, set the new properties on it.
         var existingModel = Backbone.Relational.store.find( this.model, model[ this.model.prototype.idAttribute ] );
  </code></pre>
  
  <hr>
  
  <p>The problem is related to <code>_.bindAll(this)</code> because if I comment it, it works properly.<br>
  Why? Any ideas?</p>
  
  <hr>