Angular 7可观察的等待变量为false

Question

以下可观察到：

import { Injectable } from '@angular/core';
import { HttpClient } from '@angular/common/http';
import { CookieService } from 'ngx-cookie-service';
import { Observable } from 'rxjs';

@Injectable()
export class AuthService {
    readonly loginUrl = <login_url>;
    readonly authStatusUrl = <auth_status_url>;
constructor(private http: HttpClient, private cookieService: CookieService) {}

loggingIn = false;

login(username: string, password: string) {
    this.loggingIn = true;
    const creds = {
        username: username,
        password: password
    };
    this.http
    .post<any>(this.loginUrl, creds, {})
    .subscribe(
        data => this.onLoginSuccess(data),
        error => this.onLoginFail(error));
}

handleAuth(): Observable<any> {

    const token = this.cookieService.get('token');
    const refresh = this.cookieService.get('refresh');

    // should wait for loggingIn to be false
    return this.http
        .post<any>(this.authStatusUrl, { }, {
            headers: {
                token: token,
                refresh: refresh
            }
        });
}

public onLoginSuccess(data) {
    this.loggingIn = false;
    this.cookieService.set('token', data.access_token);
    this.cookieService.set('refresh', data.refresh_token);
}

onLoginFail(err) {
    console.log('Faild to login');
    this.loggingIn = false;
}

}

在局部变量为false之前，不应执行此操作。

我读到应该使用Promises和await运算符进行异步函数调用来完成此操作，但是我找不到可以轮询变量值的东西，只能“等待一段时间并解决”。

主要思想是调用handleAuth，并在内部通过等待局部变量（或发生的事情）来确保登录未在进行中

Answer 1

为此，可以在局部变量上使用setter：

private _localVariable;


set localVariable(value) {
  this._localVariable = value;
  if(this._localVariable) {
   //call your function here.
  }
}

Answer 2

您可以做的是使loggingIn为Subject ，将“ done”事件推送到loggingIn ，然后将flatMap loggingIn送到http.post 。