angular – 如何取消订阅路径解析类中的observable

在ngOnDestroy方法中,我取消订阅我订阅的一个observable,否则代码被多次执行…

ngOnInit()
{
    this.sub = this.route.params.subscribe(params => 
    {
        this.projectId = +params['id'];
        this.projectStore.project = this.projectId;

        // load data when the route changes
        this._tasksService.gettasks(this.projectId).subscribe(years => { this.tasks = years.map(y => new task(y)) }); // no need to clean up the subscription

    });
    // load data when the component is initialized
    this._tasksService.gettasks(this.projectId).subscribe(years => { this.tasks = years.map(y => new task(y)) }); // no need to clean up the subscription

}

ngOnDestroy()
{
    this.sub.unsubscribe();
}

现在我想把它放在路由器解析类中,但是没有ngOnDestroy – 当然 – 只是一个我再次订阅的NavigationEnd事件.

这意味着我订阅了一个NavigationStart事件(当我离开路线时发生)以取消订阅另一个订阅,这是路由参数更改订阅HAHAHA …

我想这不是可行的方法,但谷歌什么也没提供.

任何人都知道如何处理这种情况？或者应该路由params更改订阅真的只属于一个组件？

constructor(private service: TasksService,private router: Router)
  {

   this.navigationEnded = this.router.events
      .filter(event => event instanceof NavigationStart)
      .map(() => this.router.routerState.root)
      .subscribe((event) =>
      {
         this.navigationEnded.unsubscribe();
      });
  }

UPDATE

当我将此代码放入resolve方法时：

this.route.params.subscribe(params => 
    {
         // reload data by the new id parameter does not work with params
         // I have to use inside here: route.params['id']
    });

params数组中没有id,它的长度为0.

相反,我必须在params订阅中使用route.params [‘id’],但为什么呢？

this.router.events
  .filter(event => event instanceof NavigationStart)
  .map(() => this.router.routerState.root)
  .first()
  .subscribe((event) =>
  {
     //this.navigationEnded.unsubscribe();
  });