title: Ember.js - How do I set the property of an element within an ArrayProxy?
body: <p>If I'm using an ArrayProxy in my model, I cannot find a way to update the properties of a specific element within that array.</p>
  
  <p>Here's my sample route and controller:</p>
  
  <pre><code>App.IndexRoute = Ember.Route.extend({
    model: function() {
      return Ember.ArrayProxy.create({
          content : [
              { firstName : "Bob", lastName : "Smith" }, 
              { firstName : "George", lastName : "Jhnsn"}
          ]
      });
    }
  });
  
  
  App.IndexController = Ember.Controller.extend({
      actions : {
          fixGeorgesLastName : function(){
              // how to I change the last name to 'Johnson' ???
              console.log(this.get("model").objectAt(1).lastName); // Jhnsn
              var georgeObjFromModel = this.get("model").objectAt(1);
              console.log(georgeObjFromModel.lastName); // Jhnsn
  
              // georgeObjFromModel.objectAt(1).lastName = "Johnson";  // error !!!  TypeError: Object #&lt;Object&gt; has no method 'objectAt'
  
          }
      }
  });
  </code></pre>
  
  <p>How do I change the <code>lastName</code> value of the second element?</p>
  
  <p>I can figure out how to do it for a local version of the same array:</p>
  
  <pre><code>// local instance of same array
  var localCustomerArray = Ember.ArrayProxy.create({
      content : [
          { firstName : "Bob", lastName : "Smith" }, 
          { firstName : "George", lastName : "Jhnsn"}
      ]
  });
  
  // works fine
  console.log("before: " + localCustomerArray.objectAt(1).lastName);  // Jhnsn
  localCustomerArray.objectAt(1).lastName = "Johnson";
  console.log("after: " + localCustomerArray.objectAt(1).lastName);  // Johnson
  </code></pre>
  
  <p>Any idea what I'm doing wrong?</p>