Question

我正在尝试根据用户是否具有状态admin（isAdmin = true）来保护URL。服务AdminAuthGuard通过调用服务UserService中的get（uid）函数来检查用户是否具有此管理状态。此get函数调用AppUser接口，该接口概述了相关字段。

使用AngularFire 2从Firebase数据库中检索数据。请参阅下面的版本详细信息。

我得到的错误是：

ERROR in src/app/admin-auth-guard.service.ts(21,17): error TS2345: Argument of type '(user: {}) => AngularFireObject<AppUser>' is not assignable to parameter of type '(value: {}, index: number) => ObservableInput<{}>'.
  Type 'AngularFireObject<AppUser>' is not assignable to type 'ObservableInput<{}>'.
    Type 'AngularFireObject<AppUser>' is not assignable to type 'Iterable<{}>'.
      Property '[Symbol.iterator]' is missing in type 'AngularFireObject<AppUser>'.
src/app/admin-auth-guard.service.ts(21,51): error TS2339: Property 'uid' does not exist on type '{}'.

错误似乎引用的行是：

switchMap(user => this.userService.get(user.uid))

我的系统设置：

Angular CLI: 6.0.1
Node: 10.1.0
rxjs: 6.1.0
Firebase: 5.0.2
AngularFire2: 5.0.0-rc.8.0

管理-AUTH-guard.service.ts

import { Injectable } from '@angular/core';
import { CanActivate } from '@angular/router';
import { Observable } from 'rxjs';
import { map, switchMap } from 'rxjs/operators';
import { AuthService } from './auth.service';
import { UserService } from './user.service';
import { AppUser } from './models/app-user';

@Injectable({
  providedIn: 'root'
})
export class AdminAuthGuard implements CanActivate {

  constructor(private userService: UserService, private auth: AuthService) { }

  canActivate(): Observable<boolean> {
    return this.auth.user$.pipe(
      switchMap(user => this.userService.get(user.uid))
      .map(appUser => appUser.isAdmin)
    );
  }
}

user.service.ts

import { Injectable } from '@angular/core';
import { AngularFireDatabase, AngularFireObject } from 'angularfire2/database';
import * as firebase from 'firebase';
import { AppUser } from './models/app-user';

@Injectable({
  providedIn: 'root'
})
export class UserService {

  constructor(private db: AngularFireDatabase) { }

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

app-user.ts（用户模型）

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

Answer 1

您收到错误是因为您使用的是Array.map而不是rxjs地图。您必须将新语法与pipe

一起使用

canActivate(): Observable<boolean> {
  return this.auth.user$.pipe(
    switchMap(user => this.userService.get(user.uid))
    .pipe(
      map(appUser => appUser.isAdmin)
    )
  );
}

Answer 2

我在这里找到答案 Working with AngularFireObject and switchMap

canActivate(): Observable<boolean>{
    return this.auth.user$
    .pipe(switchMap(user => this.userService.get(user.uid).valueChanges()))
    .pipe(map (appUser => appUser.isAdmin));    }

Answer 3

感谢 user4807496，他们的解决方案对我有用，我看到主要区别在于在 valueChanges() 之后添加了 get(user.uid)

但是，我的基于最新版本的 angular 进行了一些修改，没有空字段。为了确保您获取的内容不为空，您需要添加一个感叹号。

此外，您不需要将两个管道链接在一起，您可以简单地将 switchMap 和 map 放在一个管道中并用逗号分隔它们。（在rxjs pipeable operators docs中查看更多）


export class AdminAuthGuardService implements CanActivate{

constructor(private auth: AuthService, private userService: UserService){ }


canActivate(): Observable<boolean> {

 return this.auth.user$
  .pipe(
   switchMap( user => this.userService.get(user!.uid).valueChanges()),
   map(appUser => appUser!.isAdmin)
   );
  }

}

AngularFire2：Observable的问题

3 个答案: