AngularJS factory http returns empty

问题:

I'm trying AngularJS for the first time. I'm getting JSON data from a http-get request using a factory, but the object is returned empty, before the ajax-request is done.

Factory:

myDemo.factory('photosFactory', function($http) {
    var photos = [];

    var factory = {};

    factory.getPhotos = function() {
        $http({
            url: 'content/test_data.json',
            method: 'GET'
        }).success(function(data, status, headers, config) {
            photos = data;
            return photos;
        });
    };
    return factory;
});

Controller:

controllers.AppCtrl = function($scope, $location, $http, photosFactory) {
    $scope.photos = [];
    init();
    function init() {
        $scope.photos = photosFactory.getPhotos();
    }
};

This is what I've come up with. When the controller set $scope.photos, the value is empty as if it returns the photos array before it get populated with the ajax response.

回答1:

You should modify your code to return a promise and use the value in controller pls see dummy modified code

myDemo.factory('photosFactory', function($http) {
 return{
    getPhotos : function() {
        return $http({
            url: 'content/test_data.json',
            method: 'GET'
        })
    }
 }
});

and controller -

controllers.AppCtrl = function($scope, $location, $http, photosFactory) {
    $scope.photos = [];
    photosFactory.getPhotos().success(function(data){
       $scope.photos=data;
   });
};

回答2:

Using the q promise library means your success function can stay in your service:

app.factory('Data', function ($http, $q) {
    return {
        ajaxItems: function () {
            var deferred = $q.defer();
            $http({ method: "POST", url: "/Home/GetSearchResults" })
                .success(function (data, status, headers, config) {
                    deferred.resolve(data);
                }).error(function (data, status, headers, config) {
                    deferred.reject(status);
                });
            return deferred.promise;
        }
    }
});

app.controller('ResultsCtrl', ['$scope', 'Data', function ($scope, Data) {
    $scope.get = function () {
        $scope.items = Data.ajaxItems();
        //the model returns a promise and THEN items
        $scope.items.then(function (items) {
            $scope.items = items;
        }, function (status) {
            console.log(status);
        });
    };
}]);

回答3:

Using the $resource will let you achieve what you want, plus give you much more control compared to $http

(Do not forget to include ngResrouce as a dependency to your app.)

myDemo.factory('photosFactory', function($resource) {
    var factory = {};

    factory.getPhotos = $resource('content/test_data.json', {}, {
        'query': {method: 'GET', isArray: true}
    });
    return factory;
});

controllers.AppCtrl = function($scope, $location, $http, photosFactory) {
    $scope.photos = [];
    init();
    function init() {
        $scope.photos = photosFactory.getPhotos.query();
    }
};