title: Angularjs filter negated
body: <p>I have a set of items that I want to filter in ng-repeat using an ng-model as the string to filter the set, so far I haven't found a way to make it work when the expression is negated, I'm doing something like this:</p>
  
  <pre><code>&lt;select ng-model="languageOrigin" ng-change="updatePrice()"&gt;
               &lt;option ng-repeat="language in languages"&gt;{{language}}&lt;/option&gt;
  &lt;/select&gt;
  &lt;select ng-model="languageDestination" ng-change="updatePrice()"&gt;
              &lt;option ng-repeat="language in languages | filter:!languageOrigin"&gt;{{language}}&lt;/option&gt;
  &lt;/select&gt;
  </code></pre>
  
  <p>In the <a href="http://docs.angularjs.org/api/ng.filter%3afilter">documentation</a>, it says that we should use ! to negate the expression but still no luck.</p>
  
  <p>What am I doing wrong? </p>