title: How to let Angular JS ng-init only under certain condition?
body: <p>Let say I have the following short input form:</p>
  
  <pre><code>&lt;form ng-controller="parentController" action="testing.php" method="post"&gt;
      &lt;input name="parentInputField" ng-model="x"&gt;
      &lt;div ng-controller="childController"&gt;
          &lt;div ng-repeat="item in itemList"&gt;
              &lt;input name="childInputField[]" ng-model="x"&gt;
          &lt;/div&gt;
      &lt;/div&gt;
  &lt;/form&gt;
  </code></pre>
  
  <p>As you may already know, the model x in childController will follow the value of of model x in parentController until the user type in something in the childController input field, so the user can simply change the value in parent for bulk input and then fine tune in child.</p>
  
  <p>Now, after the user have submitted the form, I want to call the same form for editing function. To keep the bulk input function on new items, is there a way I can ng-init model x in childController only when there is a previous value?</p>