title: Ember - dynamic value binding
body: <p>I have a seemingly simple requirement in an Ember app that is giving me fits.</p>
  
  <p>I want to take this:</p>
  
  <pre><code>{{view Ember.TextField valueBinding="fields.firstName"}}
  </code></pre>
  
  <p>And make the firstName field a variable.  This is the intent, but obviously doesn't work:</p>
  
  <pre><code>{{view Ember.TextField valueBinding="fields.{{fieldName}}"}}
  </code></pre>
  
  <p>Am I missing something obvious?  This seems like it should be a very basic thing, but I've tried probably 10 different things I think "should" work but none of them work as intended.</p>