<select ng-model="selectedMovieId" ng-if="movies.length>0" ng-options="movie.id as movie.title for movie in movies track by movie.id"></select>
  <div>
    {{selectedMovieId||'No movie selected'}}
  </div>

var app = angular.module("movieApp", []);

app.controller("movieCtrl", ["$scope", "$http", function($scope, $http) {
  $scope.apiKey = ''
  var baseUrl = 'https://api.themoviedb.org/3/'
  $scope.movies = []
  $scope.searchMovie = function() {
    var url = baseUrl + 'search/movie?api_key=' + $scope.apiKey + '&query=' + $scope.queryString;
    $http.get(url)
      .then(function(response) {
        $scope.movies = response.data.results;
      }, function() {
        console.log("some error");
      })
  }
  $scope.getCredits = function() {
    var url = baseUrl + 'movie/' + $scope.selectedMovieId + '/credits?api_key=' + $scope.apiKey
    console.log(url)
    console.log($scope.movies)
      /*$http.get(url)
          .then(function(response) {
              console.log(response.data)
              $scope.actors = response.data.results;
          }, function() {
              console.log("some error");
          })*/
  }
}]);

<div ng-app="movieApp" ng-controller="movieCtrl">
  <input type='text' ng-model='queryString' ng-submit="searchMovie()">
  <button ng-click="searchMovie()">
    Search
  </button>
  <hr/>
  <select ng-model="selectedMovieId" ng-if="movies.length>0" ng-options="movie.id as movie.title for movie in movies track by movie.id">
  </select>
  <div>
    {{selectedMovieId||'No movie selected'}}
  </div>
  <button ng-if="movies.length>0" ng-click="getCredits()">
    Get Credits
  </button>
</div>