for 循环内的异步函数（解析查询）

Question

我正在尝试从 Parse.com 获取所有帖子，并检查当前用户是否喜欢每个帖子。据我了解，内部查询无法在 for 循环内完成，因为它是一个异步函数。我不明白如何以允许我检查每个帖子的方式对其进行格式化。我试过 $q.defer() 但它也没有工作。任何帮助将不胜感激

var imageGallery = Parse.Object.extend("Gallery");
var query = new Parse.Query(imageGallery);

query.include("user");
query.near("location", $rootScope.currentLocation);
query.find({
  success: function(results) {
    var i = 0;
    for (i; i < results.length; i++) {
      var object = results[i];

      var galleryLike = Parse.Object.extend("GalleryLike");
      var likeQuery = new Parse.Query(galleryLike);

      likeQuery.include('gallery');
      likeQuery.include('user');
      likeQuery.equalTo('gallery', object);
      likeQuery.equalTo('user', Parse.User.current());
      likeQuery.find({
        success: function(res) {
          if (res.length == 0) {
            var like = "false";
          } else {
            var like = "true";
          }
        },
        error: function(error) {

        }
      });

      var distance = object.get('location').kilometersTo($rootScope.currentLocation);

      self.images.push({
        object: object,
        locationName: object.get('locationName'),
        caption: object.get('caption'),
        img: object.get('img').url(),
        username: object.get('user').get('username'),
        userprofpic: object.get('user').get('profpic').url(),
        distance: distance,
        isLiked: like
      });
    }
    $scope.$apply();
    $ionicLoading.hide();
  },
  error: function(error) {
    $ionicLoading.hide();
  }
});

Answer 1

定义一个只得到一个帖子的函数，比如getPost()，它会返回一个promise。 然后你可以像下面这样使用$q.all()：

var promises = [];    
for (var i < results.length; i++) {
    promises.push(getPost(i));
}
$q.all(promises)
    .then(function(results){
        // results[i] is relevant to post #i
    });