Javascript 如何在角度工厂中保留范围上的数据

我正在学习爱奥尼亚，我正在做一个辅导。一切都很好，直到我创建了一个访问Web服务的工厂

当我访问作用域中的变量时，它们没有被定义，或者只是像我初始化变量一样

这是密码

Controller.js

angular.module('songhop.controllers', ['ionic', 'songhop.services'])

/*Controller for the discover page*/
    .controller('DiscoverCtrl', function($scope, $timeout, User, Recommendations) {
      // get our first songs
      Recommendations.getNextSongs()
        .then(function(){
          $scope.currentSong = Recommendations.queue[0];
          console.log($scope.currentSong);
        });

      console.log(Recommendations.queue);
      console.log($scope.currentSong);
      // Fired when a song is favorited or skiped
      $scope.sendFeedback = function (bool){
    Recommendations.nextSong();

    // First add to favorites if they favorited
    if (bool) User.addSongToFavorites($scope.currentSong);

    $scope.currentSong.rated = bool;
    $scope.currentSong.hide = true;

    $timeout(function() {
      $scope.currentSong = Recommendations.queue[0];
    }, 250);
  };

})


/*
Controller for the favorites page
*/
.controller('FavoritesCtrl', function($scope, User) {
  // get the list of our favorites from  the user service
  $scope.favorites = User.favorites;

  $scope.removeSong = function(song, index) {
    User.removeSongFromFavorites(song, index);
  };
})

  angular.module('songhop.services', []).factory('User', function() {

  var o = {
    favorites: []
  }


  o.addSongToFavorites = function(song){
    // Make sure there is a song to add
    if (!song) return false;

    // Add to favorites array
    o.favorites.unshift(song);
  }

  o.removeSongFromFavorites = function(song, index) {
    // make sure there is a song to remove
    if (!song) return false;

    // remove to favorites array
    o.favorites.splice(index, 1);
  }

  return o
})

.factory('Recommendations', function($http, SERVER) {
  var p = {
    queue: []
  };

  p.getNextSongs = function() {
    return $http({
      method: 'GET',
      url: SERVER.url + '/recommendations'
    }).success(function(data){
      // merge data into the queue
      p.queue = p.queue.concat(data);
    });
  };

  p.nextSong = function() {
    // pop the index 0 off
    p.queue.shift();

    // low on the queue? lets fill it up
    if (p.queue.length <= 3) {
      p.getNextSongs();
    }

  };
  return p;

})

Service.js

angular.module('songhop.controllers', ['ionic', 'songhop.services'])

/*Controller for the discover page*/
    .controller('DiscoverCtrl', function($scope, $timeout, User, Recommendations) {
      // get our first songs
      Recommendations.getNextSongs()
        .then(function(){
          $scope.currentSong = Recommendations.queue[0];
          console.log($scope.currentSong);
        });

      console.log(Recommendations.queue);
      console.log($scope.currentSong);
      // Fired when a song is favorited or skiped
      $scope.sendFeedback = function (bool){
    Recommendations.nextSong();

    // First add to favorites if they favorited
    if (bool) User.addSongToFavorites($scope.currentSong);

    $scope.currentSong.rated = bool;
    $scope.currentSong.hide = true;

    $timeout(function() {
      $scope.currentSong = Recommendations.queue[0];
    }, 250);
  };

})


/*
Controller for the favorites page
*/
.controller('FavoritesCtrl', function($scope, User) {
  // get the list of our favorites from  the user service
  $scope.favorites = User.favorites;

  $scope.removeSong = function(song, index) {
    User.removeSongFromFavorites(song, index);
  };
})

  angular.module('songhop.services', []).factory('User', function() {

  var o = {
    favorites: []
  }


  o.addSongToFavorites = function(song){
    // Make sure there is a song to add
    if (!song) return false;

    // Add to favorites array
    o.favorites.unshift(song);
  }

  o.removeSongFromFavorites = function(song, index) {
    // make sure there is a song to remove
    if (!song) return false;

    // remove to favorites array
    o.favorites.splice(index, 1);
  }

  return o
})

.factory('Recommendations', function($http, SERVER) {
  var p = {
    queue: []
  };

  p.getNextSongs = function() {
    return $http({
      method: 'GET',
      url: SERVER.url + '/recommendations'
    }).success(function(data){
      // merge data into the queue
      p.queue = p.queue.concat(data);
    });
  };

  p.nextSong = function() {
    // pop the index 0 off
    p.queue.shift();

    // low on the queue? lets fill it up
    if (p.queue.length <= 3) {
      p.getNextSongs();
    }

  };
  return p;

})

---

因为$scope变量应该是全局变量，所以没有将$scope.currentSong变量设置为它应该设置的值，对吗？

第二个和第三个控制台日志不会返回任何数据，因为它们在执行推荐返回的承诺之前执行了。getNextSongs（）已解决

第一个显示数据，因为您已将其正确地放置在then块中，该块仅在承诺解析时执行。即，当方法建议.getNextSongs（）完成时

如果您像下面这样更新代码，每个控制台将记录一些内容：

  Recommendations.getNextSongs()
        .then(function(){
          $scope.currentSong = Recommendations.queue[0];
             console.log($scope.currentSong);
             console.log(Recommendations.queue);
              console.log($scope.currentSong);
        });

---

您确定在加载数据的

承诺完成之前，
$scope.currentSong
的
控制台.log
没有执行吗？感谢您的回复，它实际上是在承诺之前执行的。