Angular.js将数据从异步服务传递到范围

Question

我有类似的服务

app.factory('geolocation', function ($rootScope, cordovaReady) {
    return {
        getCurrentPosition: cordovaReady(function (onSuccess, onError, options) {

            navigator.geolocation.getCurrentPosition(function () {
                var that = this,
                    args = arguments;

                if (onSuccess) {
                    $rootScope.$apply(function () {
                        onSuccess.apply(that, args);
                    });
                }
            }, function () {
                var that = this,
                    args = arguments;
                if (onError) {
                    $rootScope.$apply(function () {
                        onError.apply(that, args);
                    });
                }
            }, options);
        }),
        getCurrentCity: function (onSuccess, onError) {
            this.getCurrentPosition(function (position) {
                var geocoder = new google.maps.Geocoder();
                geocoder.geocode(options,function (results, status) {
                    var city = address_component.long_name;
                });
            });
        }
    }
});

而我想从控制器那样做

function MainCtrl($scope, geolocation) {
   geolocation.getCurrentCity(function(city){
       $scope.city = city;
   });
};

getCurrentPosition工作正常,城市也确定了,但我不知道如何在控制器中访问城市.

怎么了？当调用getCurrentCity时,它会调用getCurrentPosition来确定gps coords.这个coords作为参数传递给onSuccess方法吧？所以这与我想在getCurrentCity方法中做的完全相同,但我不知道如何.如果异步地理编码器检索到了城市,我想将新数据应用于onSuccess方法.

有任何想法吗？

Answer 1

您正在处理回调和异步请求.所以你应该使用$ q服务.只需使用$ rootScope和cordovaReady依赖项将其注入您的服务中.并将承诺添加到您的函数中

getCurrentCity: function () {
    var deferred = $q.defer(); 
    this.getCurrentPosition(function (position) {
      var geocoder = new google.maps.Geocoder();
      geocoder.geocode(options,function (results, status) {
        var city = address_component.long_name;
        $rootScope.$apply(function(){
          deferred.resolve(city);
        });
      });
    });
    return deferred.promise;
}

在您的控制器中,执行以下操作来处理承诺.

function MainCtrl($scope, geolocation) {
   geolocation.getCurrentCity().then(function(result) {  //result === city
     $scope.city = result;
     //do whatever you want. This will be executed once city value is available
   });     
};

Answer 2

试试这个

function MainCtrl($scope, geolocation) {
   $scope.city = null;
   geolocation.getCurrentCity(function(city){
       $scope.city = city;
       if(!$scope.$$phase) {
            $scope.$digest($scope);
        }
   });
};

有时,在实例化控制器时,并不总是调用观察者,通过强制摘要事件,如果范围不同,你可以去你想去的地方,我相信.如果我不明白你的问题,请告诉我.

哦,我不知道我是否正确地阅读了代码,但似乎你没有在你的函数中调用onSuccess回调函数:用这个替换你的getCurrentCity函数:

getCurrentCity: function (onSuccess, onError) {
        this.getCurrentPosition(function (position) {
            var geocoder = new google.maps.Geocoder();
            geocoder.geocode(options,function (results, status) {
                var city = address_component.long_name;
                if(typeof onSuccess === 'function') {
                     onSuccess(city);
                }
            });
        });
    }