AngularJS'无法读取未定义的'then'属性'

我遇到这个问题，当我单击登录按钮时，chrome 控制台会记录以下内容：

angular.min.js：117 TypeError：无法读取未定义的属性“then” 在 m.$scope.logIn (loginModuleController.js:11)

Service:

angular.module('loginModule')
.factory('loginService', function($http){
  return{
    login: function(username, password){
      var session;
      $http.post('../server/php/auth/auth.php', {
        username: username,
        password: password
      })
      .then(function(res){
        session = res;
      });
      return session;
    },
    isLogged: function(){
      return $http.get('../angCMS/server/php/auth.php?is_logged=true');
    },
    logOut: function(){
      return $http.get('../angCMS/server/php/auth.php?logout=true');
    }
  };
});

控制器：

angular.module('loginModule')
.controller('LoginCtrl', ['$scope', 'loginService', function($scope, loginService){

  $scope.auth = false;

  $scope.username;
  $scope.password;
  $scope.logIn = function(){
    loginService.login($scope.username, $scope.password).then(function(response){

    }, function(res){

    });
  };

  $scope.isLogged = function(){
    loginService.isLogged()
    .then(function(response){
      if(response){
        $scope.auth = true;
      }
    });
  };

  $scope.logOut = function(){
    loginService.logOut()
    .then(function(response){
      if(response){
        $scope.auth = false;
      }
    });
  };

}]);

这是 html 模板：

<div class="container" ng-if="auth==false">
  <div class="col-md-4 col-md-offset-4">
    <div class="row">
      <br/><h2 align="center">Login</h2>
    </div>
    <div class="well">
        <form class="form-horizontal">
        <fieldset>
          <div class="form-group">
                <input type="text" class="form-control" placeholder="Username" ng-model="username" required>
          </div>
          <div class="form-group">
                <input type="password"  class="form-control" placeholder="Password" ng-model="password" required>
          </div>
          <div class="form-group">
                <button class="btn btn-md btn-primary btn-block" type="submit" ng-click="logIn()">Sign in</button>
          </div>
        </fieldset>
      </div>
    </form>
  </div>
</div>

PHP登录方法：

public function login($user, $pass){

        $user = htmlspecialchars(trim($user));
        $pass = md5(htmlspecialchars(trim($pass)));

        $res = $this->DB->prepare("SELECT * FROM `admin` WHERE username = :user");
        if(!$res->execute(Array(":user"=>$user)))
            die(mysql_error());

        $row = $res->fetch(PDO::FETCH_ASSOC);

        if(!$row['password'] == $pass)
            die("Errore: password errata!");

        $_SESSION['logged'] = $row;
        array_push($session, $_SESSION['logged'], true);

        return $session;
    }

这更多的是滥用承诺问题。

您可能想首先看看 Promise 是如何工作的：

• https://docs.angularjs.org/api/ng/service/ https://docs.angularjs.org/api/ng/service/$q
• https://developer.mozilla.org/en/docs/Web/JavaScript/Reference/Global_Objects/Promise https://developer.mozilla.org/en/docs/Web/JavaScript/Reference/Global_Objects/Promise

从您的服务代码：

login: function(username, password){
  var session;
  $http.post('../server/php/auth/auth.php', {
    username: username,
    password: password
  })
  .then(function(res){
    session = res;
  });
  return session;
}

When login(username, password)被调用，会话仍在undefined回来后。

这是因为$http.post()是一个异步函数，.then()子句不会立即执行。

正如所指出的斯尼克托的回答 https://stackoverflow.com/questions/37955434/angularjs-cannot-read-property-then-of-undefined/37957186#37955510, 你应该“返回$http.post()":

login: function(username, password){
  return $http.post('../server/php/auth/auth.php', {
    username: username,
    password: password
  });
}

然后参考你的控制器的logIn方法：

$scope.logIn = function(){
  loginService.login($scope.username, $scope.password).then(function(response){
    // response === 'session' 
  }, function(res){

  });
};

the response参数来自loginService.login().then()正是您想要的值session来自您之前的实现的变量。