angularjs 消息绑定直到第二个表单提交才显示

Question

我正在编写我的第一个 angularjs 应用程序，它开始变得有意义了。但是，我有一个注册表单，在某些情况下没有收到消息来提醒用户注意问题。我正在使用 Firebase 进行身份验证，效果很好。但是我通过一个唯一的用户名作为密钥来存储用户。因此，在我运行 $createUser 函数之前，我进行了一次快速查询，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。

问题是当现有用户使用此用户名时。控制台日志值打印正常，但错误消息（绑定到 $scope.authMsg）第一次没有显示——但如果我再次单击 "register" 按钮，则消息显示在预期消息 div。

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 摘要周期。

要处理这个问题，写

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

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

angularjs 消息绑定直到第二个表单提交才显示

angularjs message binding doesn't show until second form submit

javascript

angularjs

firebase