Angularjs filter negated

Question

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:

<select ng-model="languageOrigin" ng-change="updatePrice()">
             <option ng-repeat="language in languages">{{language}}</option>
</select>
<select ng-model="languageDestination" ng-change="updatePrice()">
            <option ng-repeat="language in languages | filter:!languageOrigin">{{language}}</option>
</select>

In the documentation, it says that we should use ! to negate the expression but still no luck.

What am I doing wrong?

Answer 1

'!' character prepend to the filter string, like below:

filter:'!'+languageOrigin

<select ng-model="languageOrigin" ng-change="updatePrice()">
  <option ng-repeat="language in languages">{{language}}</option>
</select>
<select ng-model="languageDestination" ng-change="updatePrice()">
  <option ng-repeat="language in languages | filter:'!'+languageOrigin">{{language}}</option>
</select>