The output of an Angular factory function is consistently null

Question

The output of an Angular factory function is consistently null

I am facing an issue with storing the currentUser object in a factory to make it accessible throughout my app. Despite ensuring that the user object is being received server side, whenever I call CurrentUserFactory.GetCurrentUser(), it returns null instead of the expected data.

angular.module('myWebApp.services')
    .factory('CurrentUserFactory', ['SettingsFactory', '$http', function(SettingsFactory, $http) {
            var CurrentUserFactory = {};
            var currentUser = null;

            CurrentUserFactory.GetCurrentUser = function() {
                if (!currentUser) {
                    $http.get(SettingsFactory.myAPIUrl + 'api/users/current', { withCredentials: true }).then(function (response) {
                        currentUser = response.data;
                    });
                }
                return currentUser;
            }

            return CurrentUserFactory;
        }
    ]);

javascript angularjs

Answer 1

Answer №1

When making an asynchronous call to $http, the function returns a promise, but the value of currentUser is initially null. In order to handle this scenario, you should return the $http promise if currentUser is null, or wrap currentUser in a promise and return that if it's not null:

angular.module('myWebApp.services')
    .factory('CurrentUserFactory', ['SettingsFactory', '$http', '$q', function(SettingsFactory, $http, $q) {
            var CurrentUserFactory = {};
            var currentUser = null;

            CurrentUserFactory.GetCurrentUser = function() {
                if (!currentUser) {
                    return $http.get(SettingsFactory.myAPIUrl + 'api/users/current', { withCredentials: true }).then(function (response) {
                        currentUser = response.data;
                        return response.data;
                    });
                }
                return $q.resolve(currentUser);
            }

            return CurrentUserFactory;
        }
    ]);

Usage:

Since the function returns a promise, you'll need to use a .then() block to access the results:

CurrentUserFactory.GetCurrentUser().then(function(currentUser) {
    console.log(currentUser);
});

Answer 2

When making an asynchronous call to $http, the function returns a promise, but the value of currentUser is initially null. In order to handle this scenario, you should return the $http promise if currentUser is null, or wrap currentUser in a promise and return that if it's not null:

angular.module('myWebApp.services')
    .factory('CurrentUserFactory', ['SettingsFactory', '$http', '$q', function(SettingsFactory, $http, $q) {
            var CurrentUserFactory = {};
            var currentUser = null;

            CurrentUserFactory.GetCurrentUser = function() {
                if (!currentUser) {
                    return $http.get(SettingsFactory.myAPIUrl + 'api/users/current', { withCredentials: true }).then(function (response) {
                        currentUser = response.data;
                        return response.data;
                    });
                }
                return $q.resolve(currentUser);
            }

            return CurrentUserFactory;
        }
    ]);

Usage:

Since the function returns a promise, you'll need to use a .then() block to access the results:

CurrentUserFactory.GetCurrentUser().then(function(currentUser) {
    console.log(currentUser);
});

The output of an Angular factory function is consistently null

Answer №1

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