Angular 2 : Observable flatMap error Cannot read property 'subscribe' of undefined

Question

我正在使用 Angular 2 最终版本，并尝试执行依赖于另一个 HTTP 请求的 HTTP 请求。

我的案例是尝试使用从另一个 http 请求 (getUser) 返回的用户 ID 作为参数来getAccount

帐户服务:

constructor(private http: Http, private userService: UserService) {
    }

getAccount(): Observable<Account> {

    let tenant: string = 'test';

    Observable.fromPromise(this.userService.getUser()).flatMap(
        user => {
            return this.http.get('/tenants/' + tenant + '/accounts/' + user.id + '/')
                .map((res: Response) => {
                    return res.json();
                });
        });
}

UserService(依赖于外部系统，按要求工作):

getUser(): Promise<User> {
    return new Promise<User>((resolve, reject) => {
        if (KeycloakService.auth.authz.token) {
            return KeycloakService.auth.authz.loadUserInfo().success((data) => {
                resolve(<User> data);
            }).error(() => {
                reject(null);
            });
        }
    });
}

从 AppComponent.ts 调用 getAccount 时:

this.accountService.getAccount().subscribe(data => { console.log('account:', data); });

我收到以下错误:

EXCEPTION: Uncaught (in promise): Error: Error in :0:0 caused by: Cannot read property 'subscribe' of undefined TypeError: Cannot read property 'subscribe' of undefined

有什么想法导致此错误吗？

谢谢

Answer 1

缺少返回

return Observable.fromPromise(this.user