angular - Observable - 开始有条件地发出

Question

有没有办法开始从可观察对象有条件地发出值？就我而言，.asObservable() 函数的订阅者应该仅在 CurrentUser 初始化后获取第一个值。

export class CurrentUser {

    private currentUser$: Observable<CurrentUser>;
    private currentUserBehaviorSubject: BehaviorSubject<CurrentUser>;

    public name: string = "";

    constructor() {
        this.currentUserBehaviorSubject = new BehaviorSubject(this);
        this.currentUser$ = this.currentUserBehaviorSubject.asObservable();
    }

    public asObservable(): Observable<CurrentUser> {
        // 
        if(user.name.length > 0){
            return this.currentUser$;
        }
        else {
            // ?????
        }
    }

    public initialize(string name){
        this.name = name;
        this.currentUserBehaviorSubject.next(this);
    }
}

export class SampleComponent {
    constructor(
        currentUser: CurrentUser
    ) {
        currentUser.asObservable().subscribe(
            (u: CurrentUser) => {
                // i only want an INITIALIZED user here
            },
            error => {},
            () => { }
        );
    }
}

Answer 1

看起来您可以在 asObservable() 方法中始终返回一个 Observable，并使用 skipUntil() 运算符抑制发射，直到 currentUserBehaviorSubject > 发出(我猜这就是你知道 CurrentUser 已初始化的方式):

public asObservable(): Observable<CurrentUser> {
    return this.currentUser$
        .skipUntil(this.currentUserBehaviorSubject);
}