在AngularJS中将服务注入到另一个服务

Question

I am trying to implement login module to AngularJS app. I try to call UserService from (this) authenticationService but UserService is undefined. What am I doing wrong now, why UserService is undefined?

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

authenticationService.factory('authenticationSvc', ['$http', '$cookieStore', '$rootScope', '$timeout', 'UserService',

function AuthenticationService($scope, $http, $cookieStore, $rootScope, $timeout, UserService) {
    var service = {};

    service.Login = Login;
    service.SetCredentials = SetCredentials;
    service.ClearCredentials = ClearCredentials;

    return service;

function Login(username, password, callback) {
        var response;

        UserService.GetByUsername(username) //UserService is unidefined!!!
                .then(function (user) {
                    if (user !== null && user.password === password) {
                        response = { success: true };
                    } else {
                        response = { success: false, message: 'Username or password is incorrect' };
                    }
                    callback(response);
                });

    }

Answer 1

EDIT : Take a look at your dependency injection: you should have the same number of elements in the dependency array as the number of arguments in your function. You inject $scope in the array, and not in the arguments. You should always inject every dependency in both, and in the right order: here, Angular thinks $scope corresponds to your $http argument, the $http service corresponds to your $cookieStore argument, and so on, until UserService that refers to the 6th element of the dependency array which is... undefined.

Try

authenticationService.factory('authenticationSvc', ['$scope','$http', '$cookieStore', '$rootScope', '$timeout', 'UserService',

    function AuthenticationService($scope, $http, $cookieStore, $rootScope, $timeout, UserService) {
    ...
    }
]);

Instead.

Also, with this line

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

You create a new module that has no dependencies ( [] ) my guess is that UserService is defined in another module, that is not injected in the present service module nor in the app's main module, thus unavailable.

For the record : angular.module(name,array) creates a new module, which depends on the modules passed in the array. angular.module(name) retreives a previously created module.

I don't think you need a new module for a single service though. If you define your Authentication service in the same module as your UserService , it will be available by default.

EDIT : Plus, be careful with your naming pattern : for instance, given your code, if I wanted to include the authentication service as a service dependency, I would have to include authenticationSvc and not authenticationService ...