无法访问 Firebase 对象属性.值显示为未定义的 ANGULARFIRE [英] Cannot access Firebase object attributes. Value displayed as undefined ANGULARFIRE

问题描述

我想自定义登录来做一个演示，但是遇到了问题.

I want to do a custom login for a demo of my doing, but I encountered a problem.

我使用用户名访问 Firebase 中的引用 url，我得到一个返回的对象.如果我想访问单个属性，我会得到未定义的值，但是如果我在我的 html {{returnedObj.name}} 中添加该值，则会显示该值.

I use the username to access a reference url inside Firebase, I get a returned object. If I want to access a single attribute, I get the undefined value, but if I add in my html {{returnedObj.name}} the value is displayed.

这是为什么?

angular.module('Demo').controller('loginCtrl', ['$scope', '$firebase', '$location',    function($scope, $firebase, $location){
$scope.user = {};
$scope.check = function(){
    console.log('https://fabritzio-demo.firebaseio.com/users/' + $scope.user.name);
    $scope.returnedObj = $firebase(new Firebase('https://fabritzio-demo.firebaseio.com/usuarios/' + $scope.user.name)).$asObject();
    alert($scope.returnedObj.name); // returns undefined value
};

}]);

推荐答案

Firebase 值是异步加载的.当 alert 触发时，该值尚未加载到 $scope.returnedObj 中.

Firebase values are loaded asynchronously. The value will not yet have been loaded into $scope.returnedObj when the alert fires.

有几种方法可以处理从 Firebase 异步加载的值，例如使用 $loaded 来获取承诺:

There are a couple of ways to handle values loading asynchronously from Firebase, for example using $loaded to get a promise:

$scope.returnedObj.$loaded().then(function () {
  alert($scope.returnedObj.name);
});

该值显示在模板中是因为 Angular 会监视所有 $scope 变量的变化.加载值时(毫秒后)，立即显示.

The value is displayed in the template because Angular watches all $scope variables for changes. When the value is loaded (milliseconds later), it is immediately displayed.

这篇关于无法访问 Firebase 对象属性.值显示为未定义的 ANGULARFIRE的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！