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How to return a resolved promise from an AngularJS Service using $q?

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Happy的楠姐
Happy的楠姐 2020-12-05 17:23

My service is:

myApp.service(\'userService\', [
  \'$http\', \'$q\', \'$rootScope\', \'$location\', function($http, $q, $rootScope, $location) {
    var defe
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7条回答
  • 夕颜
    2020-12-05 17:35

    From your service method:

    function serviceMethod() {
    return $timeout(function() {
        return {
            property: 'value'
        };
    }, 1000);
}

    And in your controller:

    serviceName
    .serviceMethod()
    .then(function(data){
        //handle the success condition here
        var x = data.property
    });
    0 讨论(0)
  • 情话喂你
    2020-12-05 17:36

    Return your promise , return deferred.promise.
    It is the promise API that has the 'then' method.

    https://docs.angularjs.org/api/ng/service/$q

    Calling resolve does not return a promise it only signals the promise that the promise is resolved so it can execute the 'then' logic.

    Basic pattern as follows, rinse and repeat
    http://plnkr.co/edit/fJmmEP5xOrEMfLvLWy1h?p=preview

    <!DOCTYPE html>
<html>

<head>
  <script data-require="angular.js@*" data-semver="1.3.0-beta.5" 
        src="https://code.angularjs.org/1.3.0-beta.5/angular.js"></script>
  <link rel="stylesheet" href="style.css" />
  <script src="script.js"></script>
</head>

<body>

<div ng-controller="test">
  <button ng-click="test()">test</button>
</div>
<script>
  var app = angular.module("app",[]);

  app.controller("test",function($scope,$q){

    $scope.$test = function(){
      var deferred = $q.defer();
      deferred.resolve("Hi");
      return deferred.promise;
    };

    $scope.test=function(){
      $scope.$test()
      .then(function(data){
        console.log(data);
      });
    }      
  });

  angular.bootstrap(document,["app"]);

</script>

    0 讨论(0)
  • 北恋
    2020-12-05 17:44

    For shorter JavaScript-Code use this:

    myApp.service('userService', [
  '$q', function($q) {
    this.initialized = $q.when();
    this.user = {
      access: false
    };
    this.isAuthenticated = function() {
      this.user = {
        first_name: 'First',
        last_name: 'Last',
        email: 'email@address.com',
        access: 'institution'
      };
      return this.initialized;
    };
  }
]);

    You know that you loose the binding to userService.user by overwriting it with a new object instead of setting only the objects properties?

    Here is what I mean as a example of my plnkr.co example code (Working example: http://plnkr.co/edit/zXVcmRKT1TmiBCDL4GsC?p=preview):

    angular.module('myApp', []).service('userService', [
    '$http', '$q', '$rootScope', '$location', function ($http, $q, $rootScope, $location) {
    this.initialized = $q.when(null);
    this.user = {
        access: false
    };
    this.isAuthenticated = function () {
        this.user.first_name = 'First';
        this.user.last_name = 'Last';
        this.user.email = 'email@address.com';
        this.user.access = 'institution';
        return this.initialized;
    };
}]);

angular.module('myApp').controller('myCtrl', ['$scope', 'userService', function ($scope, userService) {
    $scope.user = userService.user;
    $scope.callUserService = function () {
        userService.isAuthenticated().then(function () {
            $scope.thencalled = true;
        });
    };
}]);
    0 讨论(0)
  • -上瘾入骨i
    2020-12-05 17:47

    Here's the correct code for your service:

    myApp.service('userService', [
  '$http', '$q', '$rootScope', '$location', function($http, $q, $rootScope, $location) {

    var user = {
      access: false
    };

    var me = this;

    this.initialized = false;
    this.isAuthenticated = function() {

      var deferred = $q.defer();
      user = {
        first_name: 'First',
        last_name: 'Last',
        email: 'email@address.com',
        access: 'institution'
      };
      deferred.resolve(user);
      me.initialized = true;

      return deferred.promise;
    };
  }
]);

    Then you controller should align accordingly:

    myApp.run([
  '$rootScope', 'userService', function($rootScope, userService) {
    return userService.isAuthenticated().then(function(user) {
      if (user) {
        // You have access to the object you passed in the service, not to the response.
        // You should either put response.data on the user or use a different property.
        return $rootScope.$broadcast('login', user.email);  
      } else {
        return userService.logout();
      }
    });
  }
]);

    Few points to note about the service:

    • Expose in a service only what needs to be exposed. User should be kept internally and be accessed by getters only.

    • When in functions, use 'me' which is the service to avoid edge cases of this with javascript.

    • I guessed what initialized was meant to do, feel free to correct me if I guessed wrong.

    0 讨论(0)
  • 佛祖请我去吃肉
    2020-12-05 17:52

    Try this:

    myApp.service('userService', [
    '$http', '$q', '$rootScope', '$location', function($http, $q, $rootScope, $location) {
      var deferred= $q.defer();
      this.user = {
        access: false
      };
      try
      {
      this.isAuthenticated = function() {
        this.user = {
          first_name: 'First',
          last_name: 'Last',
          email: 'email@address.com',
          access: 'institution'
        };
        deferred.resolve();
      };
    }
    catch
    {
        deferred.reject();
    }

    return deferred.promise;
  ]);
    0 讨论(0)
  • 误落风尘
    2020-12-05 17:54

    How to simply return a pre-resolved promise in Angular

    Resolved promise:

    return $q.when( someValue );    // angular 1.2+
return $q.resolve( someValue ); // angular 1.4+, alias to `when` to match ES6

    Rejected promise:

    return $q.reject( someValue );
    0 讨论(0)
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