Question

我有一个auth服务，我想在返回之前使用angularfire从firebase检索用户记录，但数据返回得太晚。我添加了“.filter（data =＆gt; data！== undefined）”但它没有让它等待。

this.authState = this.afAuth.authState;
this.authState.subscribe(user => {
  if (user) {
    this.currentUser = user;
    this.userid = this.currentUser.uid;
    this.displayname = this.currentUser.displayName;
    this.path = '/AU/user/' + this.currentUser.uid + '/';
    this.exists = this.af.object(this.path);
      // this line of code returns data after the navbar 
      // and user components have started which is too late.
      // The filter was added to try to get it wait for the data.
    this.exists.filter(data => data !== undefined).subscribe(x => {

      if (x && (x.$value !== null)) {
        this.mobile = x.mobile;
        this.userid = x.userid;
        this.name = x.name;
        this.email = x.email;
        this.confirm = x.confirm;
          // the fields below are undefined in the console log
        console.log( 'email', this.email, 'name', this.name)
      } else {
        this.currentUser = null;
      }
  });

在谷歌搜索这个问题时，我发现也许我需要映射响应，但它没有任何区别。以下是我使用的代码

 this.exists.map(response => this.response$)
            .filter(data => data !== undefined)
            .subscribe(x => {

我尝试比较“undefined”和“null”。我已经用完了想法，请帮忙。

Answer 1

如何使用flatMap()呢？

import 'rxjs/add/operator/mergeMap`;

this.exists.flatMap(response => {
  this.response$
  .catch(error => {
    console.error(error);
    return Rx.Observable.empty();
  });
});

我导入了mergeMap运算符，尽管由于flatMap missing after upgrading to RC 6 and RxJS Beta 11和rxjs flatmap missing我们将使用flatMap。

如果您愿意，请阅读map vs flatMap。

Answer 2

 this.exists.flatMap(response => this.response$)

如何等待订阅完成角度

2 个答案: