async for each循环之后回调函数

Question

如何在async for循环之后添加回调函数？

下面是一些更好的方面：

$scope.getAlbums = function(user, callback) { 
    $scope.albumsList.forEach(function (obj, i) { 
     $scope.getAlbum(user, obj.id, function(value){ 
      $scope.albums.push(value); 
     }); 
    }); 
    // callback(); ??? 
}; 

$scope.getAlbums('guy123', function(){ 
    // forEach loop is all done! 
    console.log($scope.albums) 
}); 

控制器：

.controller('Filters', ['$scope','Imgur', function($scope, Imgur) { 

    $scope.getAlbum = function(user, id, callback) { 
     Imgur.album.get({user:user, id:id},  
      function(value) { 
       return callback(value.data); 
      } 
     ); 
    } 

    $scope.getAlbums = function(user, callback) { 
     // Callback function at end of this forEach loop? 
     // Request is async... 
     $scope.albumsList.forEach(function (obj, i) { 
      $scope.getAlbum(user, obj.id, function(value){ 
       $scope.albums.push(value); 
      }); 
     }); 
    }; 
)]}; 

服务：

.factory('Imgur', function($resource) { 
    return { 
     album : $resource('https://api.imgur.com/3/account/:user/album/:id') 
    } 
}); 

Answer 1

正如安德鲁所说的使用$q和延期对象应该可以让你实现你的目标。

你想用$q.all()这将确保所有承诺的对象都解决了，然后你可以用$http电话拨打你的电话回.then()

function MyCtrl($scope, $q, $http) { 

    $scope.albumsList = [{ 
      id: 1, 
      name: "11" 
     }, { 
      id: 2, 
      name: "22" 
     } 
    ]; 
    $scope.albums = []; 
    $scope.getAlbum = function(user, id, callback) { 
     return $http.get("https://api.imgur.com/3/account/" + user + "/album/" + id).success(
      function(value) { 
       return callback(value.data); 
      } 
     ); 
    } 
    $scope.getAlbums = function (user, callback) { 
     var prom = []; 
     $scope.albumsList.forEach(function (obj, i) { 
      prom.push($scope.getAlbum(user, obj.id, function(value){ 
       $scope.albums.push(value); 
      })); 
     }); 
     $q.all(prom).then(function() { 
      callback(); 
     }); 
    }; 
    $scope.getAlbums('guy123', function() { 
     alert($scope.albums.length); 
    }); 
} 

Example with this on jsfiddle

运作，但不

随着延期对象，你可以访问一个承诺，你可以改变连续then()一起调用。当您解析延迟对象时，它将执行foreach，然后执行您提供的回调函数。我试图进一步简化你的例子，所以它可以在jsfiddle中工作。

function MyCtrl($scope, $http, $q) { 

    $scope.albumsList = [{ 
     id: 1, 
     name: "11" 
    }, { 
     id: 2, 
     name: "22" 
    }]; 
    $scope.albums = []; 
    $scope.getAlbums = function (user, callback) { 
     var deferred = $q.defer(); 
     var promise = deferred.promise; 
     promise.then(function() { 
      $scope.albumsList.forEach(function (obj, i) { 
       $scope.albums.push(obj); 
      }); 
     }).then(function() { 
      callback(); 
     }); 
     deferred.resolve(); 
    }; 
    $scope.getAlbums('guy123', function() { 
     alert($scope.albums.length); 
    }); 
} 

Example on jsfiddle

A bit more reading on deferred and promises.

Answer 2

我t看起来像推迟http://docs.angularjs.org/api/ng.$q，特别是链接承诺可能在这里很有用。

Answer 3

$scope.getAlbums = function(user, callback) { 

     var promiseArr = []; 
     $scope.albumsList.forEach(function (obj, i) { 
      var anHttpPromise = 
      $scope.getAlbum(user, obj.id, function(value){ 
       $scope.albums.push(value); 
      }); 
      promiseArr.push(anHttpPromise); 
     }); 

     $q.all(promiseArr).then(function(){ 
      // This callback function will be called when all the promises are resolved. (when all the albums are retrived)  
     }) 
    }; 

    $scope.getAlbum = function(user, id, callback) { 
     var anHttpPromise = Imgur.album.get({user:user, id:id},  
      function(value) { 
       return callback(value.data); 
      } 
     ); 
     return anHttpPromise; 
    } 

在上面的代码：

1. 的getAlbum由返回一个承诺。
2. 收集为getAlbums列表
3. 的每个迭代的承诺，一旦所有的承诺都收集，许数组被传递给 $q.all
4. 的$q.all方法，而不是返回一个最终的承诺，其回调 功能将被触发一次阵列中的所有承诺都解决了 。

Answer 4

使用$resource承诺PR commit提名为1.1.3，我能包住$resource电话与$ q和控制自己的异步behavoir的流动。

$scope.getAlbum = function(user, id, callback) { 
    var promise = Imgur.album.get({user:user, id:id}).$promise.then(
     function(value){ 
      return callback(value.data); 
     }, 
     function(error){ 
      //Something went wrong! 
     } 
    ) 
    return promise; 
} 

$scope.getAlbums = function(user, callback) { 
    var prom = []; 
    $scope.albumsList.forEach(function (obj, i) { 
     var promise = 
     $scope.getAlbum(user, obj.id, function(value){ 
      $scope.albums.push(value); 
     }); 
     prom.push(promise); 

    }); 

    $q.all(prom).then(function() { 
     callback(); 
    }); 
}; 

$scope.getAlbums(user, function(){ 
    // Totally works, bro. 
    console.log($scope.albums); 
});