使用Firebase，即使正在记录firebase.auth().currentUser，它也是一个空值 [英] Using Firebase, firebase.auth().currentUser is a null value even though it is being logged

问题描述

我在service.TS文件中创建了一个查询，该查询显示了基于登录用户的UID的项状态":

I created a query that is in a service.TS file that shows an items "state" that is based on a logged in user's UID:

getLists(): FirebaseListObservable<any> {

firebase.auth().onAuthStateChanged(function(user) {
  if (user) {console.log("blah", firebase.auth().currentUser.uid)
    // User is signed in.
  }
});
  return this.db.list('/foods', {
    query: {
      orderByChild: 'state/'+firebase.auth().currentUser.uid+'/state',
      equalTo: 'listed'
    }
  });
}

使用此查询，我收到一条错误消息:

Using this query, I'm getting an error that reads:

未捕获(承诺):TypeError:null不是对象(评估' WEBPACK_IMPORTED_MODULE_2_firebase_app "auth" .curren‌tUser.uid').

Uncaught (in promise): TypeError: null is not an object (evaluating 'WEBPACK_IMPORTED_MODULE_2_firebase_app"auth".curren‌​tUser.uid').

使用 {console.log("blah"，firebase.auth().currentUser.uid)正确地在日志中显示UID，确认用户是登录.

Using {console.log("blah", firebase.auth().currentUser.uid), which you can see above, correctly displays the UID in the log, confirming that the user is signed in.

我不确定是否相关，但是页面的主要TS文件通过以下方式调用此查询:

I'm not sure if it's relevant but this query is being called by the page's main TS file with:

    ngOnInit() {

    this.moviesSvc.getLists()
                  .subscribe(lists => {console.log(lists); console.log("UID", firebase.auth().currentUser.uid); this.lists = lists})
  }

我需要怎么做才能正确地将UID传递给查询?

What do I need to do to correctly pass the UID to the query?

推荐答案

onAuthStateChanged() is asynchronous, so when you have the user uid in its callback, then only perform your operation, like this:

getLists(): FirebaseListObservable<any> {

    var self = this;

    firebase.auth().onAuthStateChanged(function(user) {
        if (user) {
            // User is signed in.
            var userID = user.uid;

            return self.db.list('/foods', {
                query: {
                    orderByChild: 'state/' + userID + '/state',
                    equalTo: 'listed'
                }
            });
        }
    });

}

这篇关于使用Firebase，即使正在记录firebase.auth().currentUser，它也是一个空值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！