我有设置，将执行异步HTTP请求服务的问题。

I am having problem with setting up a service that will perform asynchronous http request.

背景

我有一个后端端点 /cars.json 当你点击这个端点首次后台作业，这将获取所有信息会启动汽车。服务器然后返回响应状态为200：

I have a backend endpoint /cars.json When you hit this endpoint for the first time the background job which will fetch all the cars information gets started. Server then returns response with status 200:

{"status":"started", "percentage_completion":0, "data":null, "error":null}

连续请求该端点将继续使用更新的 percentage_completion 的

{"status":"started", "percentage_completion":45, "data":null, "error":null}
{"status":"started", "percentage_completion":90, "data":null, "error":null}

最后请求到端点将返回：

Finally the request to the endpoint will return:

{"status":"finished", "percentage_completion":100, "data": {...}, "error":null}

和幸福的日子我有一个数据，我可以把它添加到 $范围。

and happy days I have a data and I can add it to the $scope.

但我有很难让我的头周围的承诺和做事方式的角度...

But I am having hard time to get my head around the promises and angular way of doing things...

我已经上调是这样的：

   var dashboard = angular.module('dashboard', [                                                                                       
      'templates'                                                                                                                     
    ]);                                                                                                                                 

   dashboard.controller('dashboardController', ['carsService', '$scope',                                                          
        function(carsService, $scope){                                                                                             
          $scope.test = "Loading...";                                                                                                   
          carsService.get()                                                                                                        
            .then(function(response){                                                                                                   
              $scope.test = response.data;                                                                                              
            });                                                                                                                         
        }]                                                                                                                              
   );                                                                                                                                  

    dashboard.factory('carsService', ['$http', function($http){                                                                    
      var get = function(){                                                                                                             
        return $http.get('/cars.json');                                                                                            
      };                                                                                                                                
      return {                                                                                                                          
        get: get                                                                                                                        
      };                                                                                                                                
    }]);

它发送一个请求到服务器，并在与第一响应，说明该作业已被启动的范围更新测试。当我刷新页面几秒钟后，我得到了正确的数据和状态完成更新测试。

It sends a single request to the server and updates the test on the scope with the first response stating the job has been started. When I refresh the page after few seconds I get the test updated with a correct data and the finish status.

这将是一个最好的办法，棱角分明的方式:)用承诺和东西有服务和控制器自动做到这一点。

What would be a best way, angular way:) with promises and stuff to have the service and controller do it automatically.

第一件事是使用 $间隔或类似的东西，并定期重新发送。然后从（成功）的要求，但也许有更好的方法

First thing that comes to my head is to use a $interval or something similar and periodically resend the request from .then(success) but maybe there is a better way.

角文件说，一些有关进度/通知希望，但是在现阶段，我不知道如何把它

Angular documentation says something about progress/notify promise but at the moment I have no idea how to wire it in.

很显然，我不完全理解的那一刻，我刚刚介绍给他们的承诺 - 你可以分享一些技巧/关于如何处理异步请求的资源使用的角度

Obviously I don't fully understand the promises at the moment, I just got introduced to them - can you share some tips/resources on how to deal with asynchronous requests using angular?

推荐答案

我想你可以使用嵌套的承诺取得进展通知：

I guess you can use nested promise to achieve progress notify:

function get(){

    var defer = $q.defer();

    (function fetchData(){

        $http.get('/cars.json').then(function(result){
            if(result.status === 'started'){
                fetchData();
                defer.notify(result);
            }else if(result.status === 'finished'){
                defer.resolve(result);
            }
        }, function(err){
            defer.reject(err);
        })

    })()

    return defer.promise;
}

当你调用获得（），它首先调用 fetchData 从服务器请求数据。当 fetchData 解决，检查 result.status ，如果状态还没有完成，调用 fetchData 再次通知outter延迟，否则，解决outter与最终结果推迟

//in controller
carService.get().then(
    function(finalData){ $scope.test = finalData }, 
    function(err){ ... }, 
    function(notifyData){ $scope.test = notifyData }
}