javascript - Observable 不可分配给 Observable<{}>。它缺少以下属性，如名称、电子邮件、isAdmin

Question

我正在返回带有通用对象的可观察对象，如果用户存在则返回用户对象，否则返回 null。但在这个过程中，我收到如下错误:

observable<-unknown-> is not assign to observable<{}>.``` And it is missing the following properties.

auth.service.ts

import { AppUser } from './models/app-users';
import { UserService } from './user.service';
import { of } from 'rxjs';

export class AuthService {

constructor(private userObj:UserService) 

 get appUser$(): Observable<AppUser | null> {
    return this.user$.pipe(
      switchMap(user => user
        ? this.userObj.get<AppUser>(user.uid).valueChanges()
        : of(null)
      )
    );
  }

用户服务.ts:

 get(uid:string):AngularFireObject<AppUser>{
    return this.db.object('/users/' + uid);
  }

app-users.ts:

export interface AppUser {
    name: string;
    email: string;
    isAdmin: boolean;
}

如果用户不存在，如何返回null？

Answer 1

你应该这样做，通过改变返回类型。我猜你在 tsconfig.json 中使用了 strict: true 选项:

get appUser$(): Observable<AppUser | null> {
  return this.user$.pipe(
    switchMap(user => user
      ? this.userObj.get(user.uid).valueChanges()
      : of(null)
    )
  );
}