angular - 类型 'null' 的参数不可分配给参数 Angular

Question

@Injectable({ providedIn: 'root' })
export class AuthenticationService {
    private currentUserSubject: BehaviorSubject<User>;
    public currentUser: Observable<User>;

    constructor(private http: HttpClient) {
        this.currentUserSubject = new BehaviorSubject<User>(JSON.parse(localStorage.getItem('currentUser')));
        this.currentUser = this.currentUserSubject.asObservable();
    }

    public get currentUserValue(): User {
        return this.currentUserSubject.value;
    }

    login(username: string, password: string) {
        return this.http.post<any>(`${environment.apiUrl}/users/authenticate`, { username, password })
            .pipe(map(user => {
                // store user details and jwt token in local storage to keep user logged in between page refreshes
                localStorage.setItem('currentUser', JSON.stringify(user));
                this.currentUserSubject.next(user);
                return user;
            }));
    }

    logout() {
        // remove user from local storage to log user out
        localStorage.removeItem('currentUser');
        this.currentUserSubject.next(null);
    }
}

知道为什么我在最后一行 (this.currentUserSubject.next(null)) 出现错误吗？错误消息:“null”类型的参数不可分配给“User”类型的参数。最新的 typescript 版本不允许这样做吗？另一种解决方案是什么？

Answer 1

Typescript 变得更加严格。

您可以关闭严格模式或让您的可观察对象接受null:

private currentUserSubject: BehaviorSubject<User | null>;