async for each循環之後回調函數

Question

如何在async for循環之後添加回調函數？

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); 
      }); 
     }); 
    }; 
)]}; 

服務：

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

Answer 1

正如安德魯所說的使用$q和延期對象應該可以讓你實現你的目標。

你想用$q.all()這將確保所有承諾的對象都解決了，然後你可以用$http電話撥打你的電話回.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

運作，但不

隨着延期對象，你可以訪問一個承諾，你可以改變連續then()一起調用。當您解析延遲對象時，它將執行foreach，然後執行您提供的回調函數。我試圖進一步簡化你的例子，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看起來像推遲http://docs.angularjs.org/api/ng.$q，特別是鏈接承諾可能在這裏很有用。

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; 
    } 

在上面的代碼：

1. 的getAlbum由返回一個承諾。
2. 收集爲getAlbums列表
3. 的每個迭代的承諾，一旦所有的承諾都收集，許數組被傳遞給 $q.all
4. 的$q.all方法，而不是返回一個最終的承諾，其回調 功能將被觸發一次陣列中的所有承諾都解決了 。

Answer 4

使用$resource承諾PR commit提名爲1.1.3，我能包住$resource電話與$ q和控制自己的異步behavoir的流動。

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