title: NgRepeat: Multiple filters result array length with track by option
body: <p>Say I have an ng-repeat like</p>
  
  <pre><code>&lt;li ng-repeat="event in eventData | filter:search | customFilter1:someData 
  | customFilter2:someData | orderBy:predicate:reverse | limitTo:quantity 
  track by id"&gt;{{event.someAttribute}}&lt;/li&gt;
  </code></pre>
  
  <p>I wish to display a notification for empty result set with ng-hide or what have you. My problem is, how can I get all filters' combined resulting array length while keeping the track by option? I have tried </p>
  
  <pre><code>&lt;li ng-repeat="event in filtered = ( eventData | filter:search 
  | customFilter1:someData | customFilter2:someData ) | 
  orderBy:predicate:reverse | limitTo:quantity 
  track by id"&gt;{{event.someAttribute}}&lt;/li&gt;
  </code></pre>
  
  <p>and many variations, but I have not found the correct syntax to pipe all filter results to a variable or alias, after which I would be able to do </p>
  
  <pre><code>&lt;div ng-show="filtered.length === 0"&gt;No Results.&lt;/div&gt;
  </code></pre>
  
  <p>It works without the track by option. With the track by I always get a syntax error. I know the rule is to always have track by last and outside of expression. 
  Angular documentation only states</p>
  
  <pre><code>item in expression track by
  </code></pre>
  
  <p>so what is the syntax to wrap expression part and be able to track by?</p>
  
  <p><strong>Edit.</strong></p>
  
  <p>Turns out the culprit is 
      track by </p>
  
  <p>Updated question.</p>