title: checkbox ng-false-value as null
body: <p>I have a an angularjs checkboxes with the following markup:</p>
  
  <pre><code>&lt;div class="ml20" ng-repeat="rate in auraInfo.rates"&gt;
      &lt;label class="aura-checkbox"&gt;
           &lt;input type="checkbox" 
                  ng-model="model.checkedRates[$index]" 
                  ng-true-value="{{ rate.id }}" 
                  ng-false-value="????" /&gt;
      &lt;/label&gt;
  &lt;/div&gt;
  </code></pre>
  
  <p><strong>checkedRates</strong> is an array that gets filled with identifiers when the user is checking the checkboxes. There's also a button that sends these identifiers to the server. If the user check and uncheck the same checkbox <strong>a "false" value is sent to server.</strong></p>
  
  <p>How can I set a null value (or fully remove the item from the array) when the checkbox is unchecked?</p>
  
  <p>Thanks in advance :)</p>