Angular 2 reload route on param change

问题:

I am currently writing my first Angular 2 Application. I have an OverviewComponent which has the following simple template:

<div class="row">
  <div class="col-lg-8">
    <router-outlet></router-outlet>
  </div>
  <div class="col-lg-4">
    <app-list></app-list>
  </div>
</div>

when accessing the url / my router redirects me to /overview which then loads a map within the router-outlet. The <app-list> has a list of clickable items which triggers a <app-detail> to be displayed instead of the app component. Therefor I pass the id of the referring json file in the url like that: /details/:id (in my routes).

All of the above works totally fine. If I now click on one of the list items the details are shown, BUT when I select another list element the view doesn't change to the new details. The URL does change but the content is not reloaded. How can I achieve a Reinitialization of the DetailComponent?

回答1:

As per the first final release, this is resolved.

Just pay much attention to correctly reset the state of the component when the parameter changes

this.route.params.subscribe(params => {
    this.param = params['yourParam'];
    this.initialiseState(); // reset and set based on new parameter this time
});

回答2:

You can change the routeReuseStrategy directly at the component level:

constructor(private router: Router) {

      // force route reload whenever params change;
      this.router.routeReuseStrategy.shouldReuseRoute = () => false;

}

Likewise, the reuse strategy can be changed globally.

This does not necessarily address your problem directly but seeing how this question is the first search result for "angular 2 reload url if query params change" it might save the next person from digging through the github issues.

回答3:

Another alternative that should be added here is to provide a RouteReuseStrategy to your module.

providers: [
  {
    provide: RouteReuseStrategy,
    useClass: AARouteReuseStrategy
  }
]

The default behaviour of the router is to reuse the route if the configuration is the same (which is the case when only changing the :id param in this question). By changing the strategy to not reuse the route, the component will be reloaded, and you do not have to subscribe to route changes in the component.

An implementation of the RouteReuseStrategy could be like this:

export class AARouteReuseStrategy extends RouteReuseStrategy {
  shouldDetach(route: ActivatedRouteSnapshot): boolean {
    return false;
  }
  store(route: ActivatedRouteSnapshot, handle: {}): void {

  }
  shouldAttach(route: ActivatedRouteSnapshot): boolean {
    return false;
  }
  retrieve(route: ActivatedRouteSnapshot): {} {
     return null;
 }
 shouldReuseRoute(future: ActivatedRouteSnapshot, curr: ActivatedRouteSnapshot): boolean {
   return false; // default is true if configuration of current and future route are the same
 }
}

I've written some about it here too:

https://pjsjava.blogspot.no/2018/01/angular-components-not-reloading-on.html

回答4:

I don't know whether there is an answer to the problem similar to the one I'm going to propose right here, so I'll do it anyway:

I managed to achieve a 'fake' reload the following way.

What I basically did is creating a Component which redirects me to the 'real' component I want to use:

@Component({
  selector: 'camps-fake',
  template: ''
})
export class FakeComponent implements OnInit {

  constructor(private _router:Router,
              private _route:ActivatedRoute)
  { }

  ngOnInit() {
    let id:number = -1;
    this._route.params.forEach((params:Params) => {
      id = +params['id'];
    });

    let link:any[] = ['/details', id];
    this._router.navigate(link);
  }

}

So by selecting a list item the router will navigate to /fake/:id which just extracts the id from the URL and navigates to the 'real' component.

I know there might be an easier, or more fancy way, but I think this solution works pretty well since the fake doesn't really attract attention. Just the 'flashing' when the page reloads is a negative aspect but as far as my css knowledge reaches there might be some transition to cover that.

回答5:

Is possible to detect any change in the parameters received, in my case I load the information using a Resolve so I don't need the parameter (only detect if it change). This is my final solution:

public product: Product;
private parametersObservable: any;

constructor(private route: ActivatedRoute) {
}

ngOnInit() {
  this.parametersObservable = this.route.params.subscribe(params => {
    //"product" is obtained from 'ProductResolver'
    this.product = this.route.snapshot.data['product'];
  });
}

//Don't forget to unsubscribe from the Observable
ngOnDestroy() {
  if(this.parametersObservable != null) {
    this.parametersObservable.unsubscribe();
  }
}

回答6:

Import Router in your Angular 7 project.

import { Router } from '@angular/router';

Create an object of the Router

constructor(private router: Router) {

}

Use routeReuseStrategy to detect router parameter change

ngOnInit() {
    this.router.routeReuseStrategy.shouldReuseRoute = () => {
      // do your task for before route

      return false;
    }
}

回答7:

this.route.paramMap.subscribe(params => {
  //fetch your new parameters here, on which you are switching the routes and call ngOnInit()
  this.ngOnInit();
 });

You just need to call ngOnInit() from inside the paramMap and it will initialise the whole page with newly loaded data.

回答8:

hope this will help.

constructor(private router: Router){
 // override the route reuse strategy

 this.router.routeReuseStrategy.shouldReuseRoute = function(){
    return false;
 }

 this.router.events.subscribe((evt) => {
    if (evt instanceof NavigationEnd) {
       // trick the Router into believing it's last link wasn't previously loaded
       this.router.navigated = false;
       // if you need to scroll back to top, here is the right place
       window.scrollTo(0, 0);
    }
});

}

回答9:

I solved it by using event, if the child component send a new link, and emit an event, then the parent can find the change and call to some reload function, which will reload the necessary data. Another option is to subscribe to the route parameters, and found when it change But I do think that the guys from angular2 should think about adding parameters to the router.navigate function, which can force the reload. (forceReload=true)

回答10:

This is currently not directly supported. See also https://github.com/angular/angular/issues/9811

What you can do is something like

<div *ngIf="doShow" class="row">
  <div class="col-lg-8">
    <router-outlet></router-outlet>
  </div>
  <div class="col-lg-4">
    <app-list></app-list>
  </div>
</div>

doShow:boolean: true;

constructor(private _activatedRoute: ActivatedRoute, private _router:Router, private cdRef:ChangeDetectorRef) {
  _router.routerState.queryParams.subscribe(
    data => {
      console.log('queryParams', data['st']); 
      this.doShow = false;
      this.cdRef.detectChanges();
      this.doShow = true;
  });
}

(not tested)

回答11:

Use this on your constructor()

this.router.routeReuseStrategy.shouldReuseRoute = () => false;

回答12:

I didn't find that any of these was a good and thorough solution for Angular 8. Some suggestions ended up creating infinite loops that resulted in, ahem, a stack overflow. Others are just too hacky for my tastes. I found a good solution online but since I can't post just a link here, I'll do the best to summarize what I did based on the link and why I think it's a solid solution. It allows you to just affect certain routes that need the behavior and not others and you don't need to roll any custom classes to make it work.

From Simon McClive's solution at https://medium.com/engineering-on-the-incline/reloading-current-route-on-click-angular-5-1a1bfc740ab2

First, modify your app-routing module configuration:

@ngModule({ imports: [RouterModule.forRoot(routes, {onSameUrlNavigation: ‘reload’})],
exports: [RouterModule] })

Next, modify the routes you want to affect. If you aren't using authentication you can omit the canActivate parameter:

export const routes: Routes = [
 {
   path: ‘invites’,
   component: InviteComponent,
   children: [
     {
       path: ‘’,
       loadChildren: ‘./pages/invites/invites.module#InvitesModule’,
     },
   ],
   canActivate: [AuthenticationGuard],
   runGuardsAndResolvers: ‘always’, //there are three options for this - see Simon's post. 'Always' is the heaviest-handed and maybe more than you need.
 }
]

Lastly, update your class to listen for the navigation event and act accordingly (being sure to unregister the listener on the way out):

export class AwesomeComponent implements OnInit, OnDestroy{

 // ... your class variables here
 navigationSubscription;

 constructor( private router: Router ) {

   // subscribe to the router events and store the subscription so
   // we can unsubscribe later

   this.navigationSubscription = this.router.events.subscribe((e: any) => {
     // If it is a NavigationEnd event, re-initalize the component
     if (e instanceof NavigationEnd) {
       this.myInitFn();
     }
   });
 }

 myInitFn() {
   // Reset anything affected by a change in route params
   // Fetch data, call services, etc.
 }

 ngOnDestroy() {
    // avoid memory leaks here by cleaning up
    if (this.navigationSubscription) {  
       this.navigationSubscription.unsubscribe();
    }
  }
}

回答13:

An idiomatic approach could be to use Observables and the | asyc pipe in your template.

(taken from https://medium.com/@juliapassynkova/angular-2-component-reuse-strategy-9f3ddfab23f5 - read more for details )

import {Component, OnInit} from '@angular/core';
import {ActivatedRoute} from '@angular/router';
import {Observable} from 'rxjs/Observable';
import 'rxjs/add/operator/pluck';

@Component({
  selector: 'app-detail-reusable',
  template: `<p>detail reusable for {{id$| async}} param </p>`
})
export class DetailReusableComponent implements OnInit {
  id$: Observable<string>;

  constructor(private route: ActivatedRoute) {
  }

  ngOnInit() {
    this.id$ = this.route.params.pluck('id');
  }
}

If you are fetching further details from a REST api, you can use switchMap for example:

import {Component, OnInit} from '@angular/core';
import {ActivatedRoute} from '@angular/router';
import {Observable} from 'rxjs/Observable';
import 'rxjs/add/operator/pluck';

@Component({
  selector: 'app-detail-reusable',
  template: `<ul><li *ngFor="let item of items$ | async">{{ item.name }}</li></ul>`
})
export class DetailReusableComponent implements OnInit {
  items$: Observable<string[]>;

  constructor(private route: ActivatedRoute) {
  }

  ngOnInit() {
    this.items$ = this.route.params.pipe(
      pluck("id"),
      switchMap(id => this.http.get<string[]>(`api/items/${id}`))  // or whatever the actual object type is
    );
  }
}

The | async pipe will automatically subscribe and the id$ or items$ observable will update when the route parameter changes triggering an API data fetch (in the items$ case) and updating the view.