angular 5 routing to same component but different param, not working

问题

I have angular 5 basic beginner level app there are just 5 components

my routing and links look like this

//copied from app.module.ts
const appRoutes:Routes = [
  {path:'',component:HomeComponent},
  {path:'items/:cat',component:ItemsComponent},
  {path:'itemdetail/:id',component:ItemdetailComponent},
  {path:'settings',component:SettingsComponent},
];

//copied from navbar.component.html
<ul>
      <li><a [routerLink]="['/']">Home</a></li>
      <li><a [routerLink]="['/items/8']">Rashion</a></li>
      <li><a [routerLink]="['/items/2']">Vegitables</a></li>
      <li><a [routerLink]="['/items/3']">Fruits</a></li>
      <li><a [routerLink]="['/items/7']">Other</a></li>
      <li><a [routerLink]="['/items/5']">Sweets</a></li>
      <li><a [routerLink]="['/settings']">Settings</a></li>          
</ul>

//copied from items.component.ts
ngOnInit(){
    this.cat = this.route.snapshot.params['cat'];
    this.itemsSrv.getItems(this.cat)
            .subscribe((data)=>{
                this.items=data;
            });
}

links only work if it is going to different component,
means I can navigate from home page to /items/2
but when I am in items component I can navigate to /items/any-parameter
although from Items i can go to home or settings component.
in short it is now working to navigate to same component even if parameter is different.

I noticed one thing, URL is getting changed but page content is same as old page not reloading new url :(

回答1:

So, the best way is using subscribe for route:

userSubscription: Subscription;
...
ngOnInit() {
   this.userSubscription = this.route.params.subscribe(
            (params: Params) => {
                 //------ some code -----
   })
}

After that, you must to unsubscribe:

ngOnDestroy(): void {
        this.userSubscription.unsubscribe()
}

回答2:

I know this is a little late but I just ran into the same issue and found a solution. You are using this.route.snapshot.params to get the id parameter. Per the Angular documentation, only use snapshot when your component instance will never be reused. Snapshot only provides the initial value of the route parameter map and does not get updated when the component is reused. This means if you route to a component by id and then (while displaying that component) try to route to a new instance of the same component with a different id, the initial component will be reused but the data will not update because ngOnInit() is not called a second time.

To fix the issue you must change;

this.cat = this.route.snapshot.params['cat'];

To use this format;

ngOnInit() {
  this.cat$ = this.route.paramMap.pipe(
    switchMap((params: ParamMap) =>
      this.itemsSrv.getItems(params.get('id')))
  );
}

The this.route.paramMap is returned from an Observable which

"implies that the route parameter map can change during the lifetime of this component".

You will probably have to modify other parts of your code to work with the Observable (cat$), but since I can only see part of your code I can't advise on other changes. In the documentation below there is a project file (hero-detail.component.ts) at the end of Milestone 3 showing how this works.

You can read the official documentation here;

Angular2+ Observable paramMap and component reuse

Hope this helps and happy coding!

回答3:

When you are navigating to the same component, Angular is not going to re-fire your ngOnInit() method. To get your code working, you will need to work with a version of the route parameters that are an observable and subscribe to changes on that. Make sure you read over the Angular Docs about routing. They have a bunch of helpful information in there.

ngOnInit(){
    this.route.paramMap
        .switchMap(params => this.itemsSrv.getItems(params.get('cat')))
        .subscribe(data => {
            this.items=data;
        });
}

You'll need to make sure that you unsubscribe from this subscription when you navigate away from this component. Here is a discussion on the best practice on how to do it.

回答4:

I have also face this problem while doing my project the best to get rid of that error is use subscribe for route and than use Ondestroy interface for unsubscribe an event

    ngOnInit{
       this._router.params.subscribe(param =>{
            // write some code
           let cat=this._router.snapshot.paramMap.get('cat');
          });
}

// after that you must unsbscribe

    ngOnDestroy(){
    }

回答5:

I think this is the best solution

constructor(route:ActivatedRoute) {
 route.params.subscribe(val => {
 // put the code from `ngOnInit` here
  });
}

The router only destroys and recreates the component when it navigates to a different route. When only route params or query params are updated but the route is the same, the component won't be destroyed and recreated. Happy to hear if helped.

回答6:

If you trying to route to the same Component with different route param. This worked for me.

 getConsingmentwithId(id: number){
    this.router.navigate(['component', id], {relativeTo: this.route.parent});
  }

来源：https://stackoverflow.com/questions/49738911/angular-5-routing-to-same-component-but-different-param-not-working