Angular 控制器无法从服务中获取数据

问题描述

背景:我正在学习 AngularJS，我编写了示例代码来为模块创建服务，并将数据从服务传递到模块的控制器之一，一切正常.

Background: I'm learning AngularJS, I've written sample code to create a service for a module, and pass the data from service into one of the module's controller, all works fine.

但是昨天当我尝试将以下服务的数据传递给控制器​​时，它只是显示数据未定义，我不知道为什么.

But yesterday when I tried to pass the following service's data into a controller, it just show the data is undefined, and I don't know why.

var notif = angular.module('testnotif',[]);

notif.service('sharedUsers', ['$http', function($http){
  var url = current_dir+'/testNotif/getAllUsersjson';
  var allUsers = [];
  var getAll = function (){
    $http.get(url)
    .success(function(data, status) {
      data.forEach(function(user){
        allUsers[user['ys_user_id']]=user;
      });

      console.log('in service');
      console.log(allUsers);//here console shows allUsers data correctly fetched from server.

      return allUsers;
      });
    };

   return {
       getAll: getAll
   };
}]);

notif.controller('notifCtrl',['$scope','$http', '$timeout','sharedUsers',
                              function($scope, $http, $timeout,sharedUsers ){

    $scope.allUsers=sharedUsers.getAll(); //shareUsers.getAll() returns nothing
    console.log('in notifCtrl');
    console.log($scope.allUsers); //console just prints 'undefined'. what goes wrong?
}]);

该服务有一个 getAll 属性，它是一个获取 allUsers 数据的函数.在控制台中，它显示 allUsers 已经填充了来自服务器的数据，但是在控制器中，当我调用这个 getAll() 函数时，它什么都不返回.我的代码有什么问题?非常感谢！

the service has a getAll property which is a function get allUsers data.in the console it shows allUsers are populated with data from server already,but in the controller, when I call this getAll() function, it returns nothing.what is the problem with my code?thank you very much!

现在我得到了正确的数据，感谢@doodeec 指出返回"错误，并建议使用promise api.并感谢@IntegrityFirst 指出了注入常量的更好方法.以下代码是工作版本，以防万一有人想知道.

now I got the data correct, thanks to @doodeec for pointing out the 'return' error, and suggesting using promise api. and thanks to@IntegrityFirst points out a better way for injecting constant. the following code is the working version, just in case anyone wants to know.

//define constant:
notif.value('current_dir', 'dir to current path');
//in module, define service
notif.service('sharedUsers', ['$http','$q','current_dir', function($http, $q, current_dir){
var url = current_dir+'/testNotif/getAllUsersjson';
var allUsers = [];

var getAll = function (){
    var deferred = $q.defer();
    $http.get(url)
    .success(function(data, status) {
        data.forEach(function(user){
            allUsers[user['ys_user_id']]=user;
        });
        console.log('in service');
        console.log(allUsers);
        deferred.resolve(allUsers);
    });
    return deferred.promise;
};
return {
     getAll: getAll
};
}]);
//in controller
notif.controller('notifCtrl',['$scope','$http', '$timeout','sharedUsers','$q',
                              function($scope, $http, $timeout,sharedUsers,$q ){
sharedUsers.getAll().then(function(data){$scope.allUsers=data;});
}]);

推荐答案

getAll 是不返回任何内容的函数，这就是为什么 $scope.allUsers 未定义

getAll is function which doesn't return anything, that's why $scope.allUsers is undefined

你可能想这样做

controller - 当 getAll 返回的承诺被解析时，代码将等待，并将该承诺返回的数据分配给范围变量

controller - code will wait while promise returned from getAll is resolved, and assign the data returned from that promise to scope variable

sharedUsers.getAll().then(function(data) { $scope.allUsers = data; });

service - $http.get 返回 promise，因此您可以在方法调用中返回它，这样您就可以对 resolve/reject 在控制器中

service - $http.get returns promise, so you can return it in method call, so you will be able to react on resolve/reject in the controller

var getAll = function (){
    return $http.get(url)
        .success(function(data, status) {
            data.forEach(function(user){
                allUsers[user['ys_user_id']]=user;
            });
            return allUsers;
        });
};

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