javascript - 直到第二个表单提交后，AngularJS消息绑定(bind)才会显示

Question

这个问题已经有答案了:

How come Angular doesn't update with scope here? (1 个回答)

已关闭 8 年前。

我正在编写我的第一个 angularjs 应用程序，它开始有意义了。但是，我有一个注册表单，在某些情况下无法收到提醒用户出现问题的消息。我正在使用 Firebase 进行身份验证，效果很好。但我通过唯一的用户名作为 key 来存储用户。所以在我运行 $createUser 之前函数中，我进行快速查询以查看是否已经存在具有此键的用户对象 - 如果没有，我将创建该用户。

问题在于现有用户使用此用户名。控制台日志值打印正常，但错误消息(绑定(bind)到 $scope.authMsg )第一次不会显示 - 但如果我再次单击“注册”按钮，则该消息将显示在预期的消息 div 中。

任何有关消息问题的提示(或对此代码的建议)将不胜感激!

$scope.register = function() {
    $scope.authMsg = '';
    var ref = new Firebase(FIREBASE_URL);
    $scope.authObj = $firebaseAuth(ref);

    // check if the username is taken
    ref.child("/users/"+$scope.account.username).on("value", function(snapshot) {
        if (snapshot.val()) {
            //
            // PROBLEM HERE!!
            //
            $scope.authMsg = 'Username exists-- did you forget your password?'; // doesn't show on page until second submit
            console.log('Username exists-- did you forget your password?'); // prints to console as expected
        } else {
            $scope.authObj.$createUser({ email: $scope.account.email, password: $scope.account.password })
            .then(function(userData) {
                console.dir(userData);
                return $scope.authObj.$authWithPassword({
                    email: $scope.account.email,
                    password: $scope.account.password
                });
            }).then(function(authData) {
                // we created a user and are now logged in-- store user info
                var userdata = {};
                userdata[$scope.account.username] = {
                                uid: authData.uid,
                                first_name: $scope.account.first_name,
                                last_name: $scope.account.last_name,
                                email: $scope.account.email,
                                full_name: $scope.account.first_name+' '+$scope.account.last_name
                            };
                var usersRef = ref.child("users");
                // save the userdata
                usersRef.set(userdata);
                console.log("Logged in as:", authData.uid);
                $state.go('app.dashboard');
            }).catch(function(error) {
                $scope.authMsg = error;
                console.error("Error: ", error);
            });
        }
    }, function (errorObject) {
        $scope.authMsg = 'The read failed: ' + errorObject.code;
        console.log('The read failed: ' + errorObject.code);
    });
};

Answer 1

我假设 Firebase 回调不涉及 Angular 摘要循环。

要处理这个问题，请编写

if (snapshot.val()) {
    $scope.$apply(function() {
        $scope.authMsg = 'Username exists— did you forget your password?';
    });

关于该主题的有用读物:http://jimhoskins.com/2012/12/17/angularjs-and-apply.html