如何处理数据时在一个循环的承诺？ [英] How to deal the data when the promise in a loop?

问题描述

这是我的方式：

var activeArr = [];
var activeDate = [];
var day = (endDate - startDate) / (24 * 60 * 60 * 1000);
for (var i = 1; i < day + 1; i++) {
    activeDate.push(endDate - (24 * 60 * 60 * 1000) * i);

    var start = endDate - (24 * 60 * 60 * 1000) * i;
    var end = endDate - (24 * 60 * 60 * 1000) * (i - 1);

    statisService.getRegStatis(start, end).then(function(data) {
        activeArr.push(data);
        if(activeArr.length == day){
            var active = [];
            for(var j=0;j<activeArr.length;j++){
                var obj = {};
                obj.date = activeDate[j];
                obj.data = activeArr[j].data;
                active.push(obj);
            }
            $scope.active = active;
        }
    });
}

该服务：

userServiceModule.factory('statisService', ['$http', 'serverUrl', function($http, serverUrl) {
return {
    getRegStatis: function(startDate, endDate) {
        var url = serverUrl + "/adminDA/dbReport?startTime=" + startDate + "&endTime=" + endDate;
        return $http.get(url).then(function(result) {
            return result.data;
        });
    }
};

我想把日期和数据合并到一个对象，这样我可以在这样的视图中使用它：

I want to put the date and the data into one object so that I can use it in the view like this:

<tr ng-repeat="item in active track by $index">

for循环不会等待所有的服务调用完成，所以我处理的数据在for循环，我认为这不是一个好办法，但我不知道该怎么做的更好。

The for loop will not wait for all the service calls to be completed,So I deal the data in the for loop,and I think this is not a good way,but I don't know how to do it better.

推荐答案

您应该使用 $ q.defer（）诺经理，从延期API 。

You should use the $q.defer() promise manager, from the deferred API.

$ q.defer（）获得2种方法：

• 解析（值）：这解决我们的相关承诺，给她终值

• resolve(value) : which resolve our associated promise, by giving her the final value

拒绝（原因）：其中一个解决错误的承诺

reject(reason) : which resolve an promise error.

另外的 $ q.all（）采取承诺数组作为参数，并解决所有的人。

Moreover $q.all() take an promises array as parameter, and resolve all of them.

控制器

(function(){

function Controller($scope, Service, $q) {

  var promises = [];

  var defer = $q.defer();

  //Process loop
  for (var i = 0; i < 20; ++i){
    //Fill my promises array with the promise that Service.post(i) return
    promises.push(Service.post(i));
  }

  //Resolve all promise into the promises array
  $q.all(promises).then(function(response){
    //Create arr by maping each data field of the response
    var arr = response.map(function(elm){
      return elm.data;
    });
    //Resolve my data when she is processed
    defer.resolve(arr);
  });

  //When the data is set, i can get it
  defer.promise.then(function(data){
    //Here data is an array
    console.log(data)
  });

}

angular
.module('app', [])
.controller('ctrl', Controller);

})();

服务

(function(){

  function Service($http){


    function post(num){
      //Just an example, I've pass an object, and just return it then
      return $http.post('path_to_url', {id:num});
    }

    var factory = {
      post: post
    };

    return factory;

  }

  angular
    .module('app')
    .factory('Service', Service);

})();

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