从Angular2服务中的订阅中获取延迟变量

Question

因此，我有以下服务/组件：

dasboard.service.ts (摘录)

@Injectable()
export class DashboardService extends RestHelpers {
    private _Manager$: Subject<Manager> = new Subject();

    constructor(private http: Http) {
        super(http);

        this.get<Manager>(url).subscribe(result => {
            this._Manager$.next(result);
        }, error => this.errorMsg = error);
    }

    get manager$(): Observable<Manager> {
        return this.Manager$.asObservable();
    }
}

rental.service.ts (摘录)

@Injectable()
export class RentalService extends RestHelpers {
    constructor(private http: Http, private _dashboardService: DashboardService) {
        super(http);

        this._dashboardService.manager$.subscribe(r => {
            this._rentals = r.Rentals;
            this._rentals$.next(this._rentals);
        });
    }

    get rentals$(): Observable<{}> {
        return this._rentals$.asObservable();
    }

    findRental(id: string): Observable<Rental> {
        return this.rentals$.map((r: Rental) => r.find(rental => r.RentalId === id));
    }
}

rental rental.Component.ts(摘录)

export class RentalDetailsComponent implements OnInit {

    private rental: Rental;
    public title = "Rental";

    constructor(private _rentalService: RentalService, private route: ActivatedRoute, private router: Router) {
        this.rental = <Rental>{};
    }

    ngOnInit() {
        this.sub = this.route.params.subscribe(params => {
            let id = params['id'];

            if (id !== undefined) {
                this._rentalService.findRental(id).subscribe((rental) => {
                    this.rental = rental;
                    this.title = rental.RentalName; 
                });
            }
        });
    }
}

在构建组件时，服务已经在另一个组件上调用了一次，当我想要将其路由到详细信息时，我永远无法获得租赁。在组件调用中，服务被初始化(构造函数运行)，但似乎subscribe方法没有产生任何结果，尽管第一次调用subscribe时，subscribe实际上正在工作。

调用顺序：

Dasboard Component --- Dashboard Service
|
+ Rental Dashboard Component --- Rental Service --- (depends on) Dashboard Service
  |
  + Rental Details Component --- Rental Service --- (depends on) Dashboard Service

租赁组件都是仪表板组件上通过路由器插座的子组件，因此它们不是直接组件。

我想过观察一个变量来等待订阅完成，我试着使用promises，但它们从来没有返回订阅的值，这是我想出的最好的方法，但它不起作用。这是我第一次使用rxjs和angular2，我无法解开这个结。我们将非常感谢您的帮助。

package.json (摘录)

"@angular/common": "2.0.0-rc.5",
"@angular/compiler": "2.0.0-rc.5",
"@angular/core": "2.0.0-rc.5",
"@angular/http": "2.0.0-rc.5",
"@angular/router": "3.0.0-rc.1",
"@angular/router-deprecated": "2.0.0-rc.2",
"@angular/upgrade": "2.0.0-rc.5",
"angular2-in-memory-web-api": "0.0.15",
"core-js": "^2.4.0",
"reflect-metadata": "^0.1.3",
"rxjs": "5.0.0-beta.6",
"systemjs": "0.19.27",
"zone.js": "^0.6.12"

Answer 1

我认为将RentalService中的observable更改为

private _rentals$: Subject<Rental> = new BehaviorSubject();

应该做你想做的事