如何在启用严格类型的情况下将 RxJs (BehaviourSubject) next() 方法设置为 null？

Question

我正在学习 rxJs 和 Angular11，看一个例子我遇到了这段代码，最后参考 logout 方法。

    import { Injectable } from '@angular/core';
import { Router } from '@angular/router';
import { HttpClient } from '@angular/common/http';
import { BehaviorSubject, Observable } from 'rxjs';
import { map } from 'rxjs/operators';

import { environment } from '@environments/environment';
import { User } from '@app/_models';

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

    constructor(
        private router: Router,
        private http: HttpClient
    ) {
        this.userSubject = new BehaviorSubject<User>(JSON.parse(localStorage.getItem('user')));
        this.user = this.userSubject.asObservable();
    }

    public get userValue(): User {
        return this.userSubject.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('user', JSON.stringify(user));
                this.userSubject.next(user);
                return user;
            }));
    }

    logout() {
        // remove user from local storage to log user out
        localStorage.removeItem('user');

        //I'm getting error -> Argument of type 'null' is not assignable to parameter of type 'User'.ts(2345)
        this.userSubject.next(null);  


        this.router.navigate(['/login']);
    }
}

有什么想法吗？我宁愿不禁用严格类型，而且我搞砸了“？”但没有运气。如果我没理解错的话，传递null只是为了清除之前那里的数据？

更新 1

所以我将 private userSubject: BehaviorSubject<User>; 更改为 private userSubject: BehaviorSubject<any>; 不确定这是否均匀 proper/correct 但应用程序运行...

更新 2 正如 Pankaj Sati 的评论所述，使用 null as any 也可以！

Answer 1

使用 union 类型

，以下应该可以工作

private userSubject: BehaviorSubject<User | null>;

在 subscribe 函数中访问 user 值时，您可能需要添加一些空值检查，但您可能已经这样做了

如何在启用严格类型的情况下将 RxJs (BehaviourSubject) next() 方法设置为 null？

How to set RxJs (BehaviourSubject) next() method as null with Strict type enabled?

rxjs

angular

angular11