AngularJS'无法读取未定义的属性'then' [英] AngularJS 'Cannot read property 'then' of undefined'

问题描述

我遇到了这个问题，当我单击登录按钮时，Chrome控制台会记录以下内容:

I've this problem, when I click on login button, the chrome console log this:

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

angular.min.js:117 TypeError: Cannot read property 'then' of undefined at m.$scope.logIn (loginModuleController.js:11)

服务:

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;
    }

推荐答案

这更多是对诺言问题的滥用.

This is more of a misuse of promises issue.

您可能想先看一下诺言的工作原理:

You might want to first take a look of how promises work:

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

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

根据您的服务代码:

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

调用login(username, password)时，返回时会话仍为undefined.

When login(username, password) is called, session is still undefined upon returning.

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

This is because $http.post() is an asynchronous function, the .then() clause does not get executed immediately.

Snixtor的答案指出， 您应该返回$http.post()的返回值":

As pointed out by Snixtor's answer, you should "return the return value of $http.post()":

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

然后引用控制器的logIn方法:

Then referring to your controller's logIn method:

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

  });
};

loginService.login().then()中的response参数恰好是您先前实现中预期的session变量的值.

the response parameter from loginService.login().then() is exactly the value of your intended session variable from your previous implementation.

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