title: ng-options doesn't work in select
body: <p>I'm trying to implement a select in my angular app to show data about tv show episodes in a table.</p>
  
  <p>In the select the user should be able to select one of the episodes.</p>
  
  <p>I tried by <code>ng-repeat</code> the option elements, which worked. But when I try to set <code>ng-options</code> for the select, they seem to be not recognized.</p>
  
  <p>Any idea, what I got wrong here?</p>
  
  <p>Here is my html:</p>
  
  <pre><code>&lt;div class="container-fluid full-height"&gt;
      &lt;div id="tabs_container" class="col-xs-12"&gt;
  
  
          &lt;div ng-app="seriesAnalyzer" ng-controller="configTableController"&gt;
              &lt;label&gt;
                  Episode:
                  &lt;select&gt;
                      &lt;option ng-repeat="episode in all_episodes | orderBy:['season_number','episode_number']"&gt;Season: {{episode.season_number}} Episode: {{episode.episode_number}}&lt;/option&gt;
                  &lt;/select&gt;
              &lt;/label&gt;
  
              &lt;!-- This is not working --&gt;
              &lt;label&gt;
                  Episode:
                  &lt;select ng-options="episode.season_number for episode in all_episodes track by id"&gt;
                      &lt;option value=""&gt;Please select an episode...&lt;/option&gt;
                  &lt;/select&gt;
              &lt;/label&gt;
  
              &lt;div ng-init="episode = episode_data"&gt;
                  &lt;p&gt;{{episode_data.episode_number}}&lt;/p&gt;
                  &lt;p&gt;{{episode_data.season_number}}&lt;/p&gt;
              &lt;/div&gt;
  
              &lt;table st-table="rowCollection" class="table table-striped"&gt;
                  &lt;thead&gt;&lt;/thead&gt;
                  &lt;tbody&gt;
                  &lt;tr ng-repeat="scene in episode_data.configuration_matrix"&gt;
                      &lt;td ng-repeat="values in scene track by $index" ng-style="set_color(values)" &gt;{{values}}&lt;/td&gt;
                  &lt;/tr&gt;
                  &lt;/tbody&gt;
              &lt;/table&gt;
  
          &lt;/div&gt;
  
          &lt;br&gt;
      &lt;/div&gt;
  &lt;/div&gt;
  </code></pre>
  
  <p>And my controller:</p>
  
  <pre><code>seriesAnalyzer.controller('configTableController', function ($scope, $http) {
  
  var req_url = 'http://localhost:8080/api/episodes';
  $http.get(req_url)
      .success(function (data) {
          $scope.all_episodes = data;
          console.log($scope.all_episodes);
      })
      .error(function (data) {
          console.log('Error: ' + data);
      });
  
  
  $scope.update_season_number = function(){
      console.log(val);
  };
  
  $scope.update_episode_number = function(){
      console.log("Input changed");
  };
  
  var get_episode_data = function()
  {
      var req_url = 'http://localhost:8080/api/episodes?season_id=' + $scope.season_number + '&amp;episode_id=' + $scope.episode_number
      $http.get(req_url)
          .success(function (data) {
              $scope.episode_data = data;
          })
          .error(function (data) {
              console.log('Error: ' + data);
          });
  };
  
  ....
  </code></pre>