Angular : Create a service using $http

Question

I try to create a service for my user. I use a request http for get the current user. For avoid to call my server each time that I call the userService.getCurrentUser() I tried to send a variable if the request has already be send or call the server if it is the first time.

Here my service :

angular.module('UserService', []) 
.factory('UserService', function($q , $http, $rootScope,$timeout) {
    var currentUser = null;

    return {
        getCurrentUser: function() {
                if (currentUser == null){
                var config = {};

                config.cache = true;
                config.method = "GET"; 
                config.url = "users/get_current_user";
            return $http(config)
                .then(function(response) {
                    if (typeof response.data === 'object') {
                            currentUser = response.data.user;
                        return response.data.user;
                    } else {
                        // invalid response
                        return $q.reject(response.data);
                    }

                }, function(response) {
                    // something went wrong
                    return $q.reject(response.data);
                });
                }
                else{
                    return currentUser;
                }
        }
        };     
});

Unfortunately I call my request few time because the promise is not immediately resolved. How can I fix this to be sure to call my server once.

And how call this function from my controller because some time the return value is an promise so I use .then() and sometime it will be the value currentUser.

urish · Accepted Answer · 2013-11-08 23:54:23Z

2

What you would need to save (and return in future invocations) is the promise itself. This way, it's guaranteed that:

You will always get a promise object from your function (consistent behavior)
You will never fire more than one request.

You can achieve this by changing your code as following:

angular.module('UserService', []) 
.factory('UserService', function($q , $http, $rootScope,$timeout) {
    var currentUserPromise = null;

    return {
        getCurrentUser: function() {
            if (currentUserPromise === null) {
                var config = {};

                config.cache = true;
                config.method = "GET"; 
                config.url = "users/get_current_user";
                currentUserPromise = $http(config)
                    .then(function(response) {
                        if (typeof response.data === 'object') {
                            return response.data.user;
                        } else {
                            // invalid response
                            return $q.reject(response.data);
                        }  
                    }, function(response) {
                        // something went wrong
                        return $q.reject(response.data);
                    });
            }
            return currentUserPromise;
        }
    }
};

answered Nov 8, 2013 at 23:54

urish

9,0738 gold badges57 silver badges75 bronze badges

Sign up to request clarification or add additional context in comments.

2 Comments

FlavienBert Over a year ago

Hello urish, first thx for your answer. Great it works verry well so like it's a promise for get the data in my controller I need to do this : UserService.getCurrentUser().then(function(user){$scope.currentUser = user;}), instead of that $scope.currentUser = UserService.getCurrentUser() ?? it's little be constraining.

urish Over a year ago

You welcome Flavien! Well, before AngularJS 1.2.0 you could get away with assigning the returned promise directly to the scope and this would work as expected, but since angular 1.2.0-rc3 this is deprecated (see github.com/angular/angular.js/issues/4158) and you should explicitly call .then() in your controller as you mentioned.

Collectives™ on Stack Overflow

Angular : Create a service using $http

1 Answer 1

2 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

2 Comments

Your Answer

Sign up or log in

Post as a guest

Related