Question

profile.page.ts:

  username: string;
  totalScore: number;
  ...


  loadUserData() {
    this.spinnerDialog.show();
    this.firebaseServie.loadUserData().then(() => {
      this.username = this.sessionData.getUser().getUsername();
      this.totalScore = this.sessionData.getUser().getTotalScore();
       ....
    });

firebase.service.ts：

async loadUserData() {
    console.log(this.sessionData.getUser().getEmail());
    this.userCollection = this.afs.collection('users', ref => ref.where('email', '==', this.sessionData.getUser().getEmail().toLowerCase()));

    this.userDoc = this.afs.collection("users").doc(this.sessionData.getUser().getEmail().toLowerCase());

    this.x = this.userDoc.valueChanges().subscribe(((item: User) => {
      this.userLoadedUser = item;
      console.log("Found user by email id " + this.sessionData.getUser().getEmail() + ":" + this.userLoadedUser.username);
      this.sessionData.getUser().setUsername(this.userLoadedUser.username);
      this.sessionData.getUser().setTotalScore(this.userLoadedUser.totalScore);
      ....

    }));
  }

那么如何确定then()子句中的部分仅在从Firebase获得数据后才执行？

为了更好的理解，我已经对问题进行了编辑。

Answer 1

由于订阅表明您正在处理一个可观察的对象，因此最好不要开始与一个承诺混为一谈，而只需使用可观察的对象和pipe

otherfunc()
    .pipe(map(myfunc))
    .subscribe((item:User) => {

});

如果您确实想要诺言，则可以将可观察者转换为诺言。

otherfunc().toPromise().then(myfunc).then(e => {
    // runs after
});

Answer 2

您只需在firebase.service.ts中返回一个新的Promise：

loadUserData() {
    return new Promise((resolve, reject) => {
        ...
        this.x = this.userDoc.valueChanges().subscribe(((item: User) => {
            ...
            resolve(); // If everything worked!
        }));
        ...
    });
}

希望对您有帮助！

TypeScript嵌套的异步函数

2 个答案: