Question

log from web不知道为什么第41行未定义。只想将值赋给局部变量“users”。能够将值分配给变量或在订阅函数内记录。

这是角度代码：

export class UserProfileComponent implements OnInit {    

  id = '';
  users;

  constructor(private route: ActivatedRoute,
              private afs: AngularFirestore,
              private afsauth: AngularFireAuth,
              public Auth: AuthService) { }

  ngOnInit() {
    const collection: AngularFirestoreCollection<any> = this.afs.collection('users');

    // Notice how the observable is separated from write options
    const collection$: Observable<any> = collection.valueChanges();
    collection$.subscribe(data => console.log(data));
    this.getuid();
  }

  //this.user = this.afsauth.auth.currentUser
  getuid(){
    this.Auth.user.subscribe((data:any) => {
      this.users = data.uid;
      console.log(data);
      console.log(this.users);
    });

    console.log(this.users);
  }
}

Answer 1

我假设问题行在这里：

getuid(){
   this.Auth.user.subscribe((data:any) => {
      this.users = data.uid
      console.log(data)
      console.log(this.users)
   });

   console.log(this.users)   // <-- Line generating the error?
}

这样做的原因是，当执行此代码时，会立即执行subscribe，然后执行最后一个console.log语句。此时，this.users未定义。

当订阅发出值时，将执行订阅中的代码。只有这样才能设置this.users属性。

Angular 4订阅无法分配值

1 个答案: