Passing route parameters to child routes in Angular 2: A step-by-step guide

Question

Passing route parameters to child routes in Angular 2: A step-by-step guide

Struggling with passing routing parameters to my component when loaded in a subroute using Angular 2 rc.1 and TypeScript, and utilizing the @angular/router-deprecated package.

In the routes configuration of my root component, I have set it up like this:

@RouteConfig([
  {path:'/top', name:'Top', component: EndPointComponent},
  {path:'/sub/...', name:'Sub', component: MiddleManComponent}
])

Below is the code for the endpoint component where parameter reading is attempted:

import {Component} from '@angular/core';
import {RouteParams} from '@angular/router-deprecated';
@Component({
    template: 'Route Params: {{routeParams.params | json}}'
})
export class EndPointComponent{
    constructor(private routeParams:RouteParams){}
}

And here's the code for the middleman component featuring the subroute to EndPointComponent:

import {Component} from '@angular/core';
import {RouteConfig, ROUTER_DIRECTIVES} from '@angular/router-deprecated';
import {EndPointComponent} from "./endpoint.component";

@Component({
    directives: [ROUTER_DIRECTIVES]
    template: `<router-outlet></router-outlet>`
})
@RouteConfig([
    {path: '/end', name: 'End', component: EndPointComponent, useAsDefault: true}
])
export class MiddleManComponent {}

When loading the component from the top-level route (e.g., 'Top' in the root component), I can successfully read parameters from the routeParams object of EndPointComponent. However, the parameters are always empty when navigating to EndPointComponent through MiddleManComponent (e.g., via the 'Sub' route in the root component).

Do children routers override parent parameters before resolving routes? This seems illogical, so I must be overlooking something. How exactly can I pass route parameters to a subroute?

PS: Attempted to create a plunker for demonstration purposes, but had difficulties figuring out why the application wouldn't load. Link to the attempt: here

typescript routes angular

Answer 1

Answer №1

When dealing with child routes, it's important to note that they have their own instance of RouteParams which is independent from the parent route. This separation helps prevent naming conflicts and promotes better encapsulation of components within the routing structure.

If you need to pass parameters from a parent route to a component loaded by a child route, one way to achieve this is by using a service.

@Injectable()
export class RouteParamService {
  constructor(private routeParams: RouteParams) {}

  get params() {
    return this.routeParams.params;
  }
}

@Component({
    template: 'Route Params: {{routeParams.params | json}}'
})
export class EndPointComponent{
    constructor(private routeParams:RouteParamService){}
}

@Component({
  directives: [ROUTER_DIRECTIVES]
  template: `<router-outlet></router-outlet>`,
  providers: [RouteParamService]
})
@RouteConfig([
  {path: '/end', name: 'End', component: EndPointComponent, useAsDefault: true}
])
class MiddleManComponent() { }

The RouteParamService will be instantiated on the same route level as the MiddleManComponent, ensuring that it shares the same instance of RouteParams. This allows the child route component to access the parent route parameters through the service injection.

If you find yourself needing multiple instances of EndPointComponent at different levels in the route tree, consider adding an additional layer of parent route between them, such as a component that contains both MiddleManComponent and EndPointComponent.

It's worth noting that RootComponent is not routed, so you won't be able to instantiate RouteParams for the RouteParamService directly from it. Instead, RouteParams is provided by the <router-outlet> component.

Answer 2

When dealing with child routes, it's important to note that they have their own instance of RouteParams which is independent from the parent route. This separation helps prevent naming conflicts and promotes better encapsulation of components within the routing structure.

If you need to pass parameters from a parent route to a component loaded by a child route, one way to achieve this is by using a service.

@Injectable()
export class RouteParamService {
  constructor(private routeParams: RouteParams) {}

  get params() {
    return this.routeParams.params;
  }
}

@Component({
    template: 'Route Params: {{routeParams.params | json}}'
})
export class EndPointComponent{
    constructor(private routeParams:RouteParamService){}
}

@Component({
  directives: [ROUTER_DIRECTIVES]
  template: `<router-outlet></router-outlet>`,
  providers: [RouteParamService]
})
@RouteConfig([
  {path: '/end', name: 'End', component: EndPointComponent, useAsDefault: true}
])
class MiddleManComponent() { }

The RouteParamService will be instantiated on the same route level as the MiddleManComponent, ensuring that it shares the same instance of RouteParams. This allows the child route component to access the parent route parameters through the service injection.

If you find yourself needing multiple instances of EndPointComponent at different levels in the route tree, consider adding an additional layer of parent route between them, such as a component that contains both MiddleManComponent and EndPointComponent.

It's worth noting that RootComponent is not routed, so you won't be able to instantiate RouteParams for the RouteParamService directly from it. Instead, RouteParams is provided by the <router-outlet> component.

Answer 3

Answer №2

By utilizing @angular/core, you have the ability to retrieve the parent ActivatedRoute.

export class ChildComponent implements OnInit {

  parentRouteId: string;

  constructor(private route: ActivatedRoute) {
  }

  ngOnInit() {
    this.route.parent.params
      .subscribe((params: Params) => this.parentRouteId = params['id']);
  }
}

Answer 4

By utilizing @angular/core, you have the ability to retrieve the parent ActivatedRoute.

export class ChildComponent implements OnInit {

  parentRouteId: string;

  constructor(private route: ActivatedRoute) {
  }

  ngOnInit() {
    this.route.parent.params
      .subscribe((params: Params) => this.parentRouteId = params['id']);
  }
}

Answer 5

Answer №3

Utilizing the "@angular/router": "3.0.0-alpha.6" library, I successfully retrieved the parent route argument by implementing the following method:

export class ChildComponent {

    private sub: any;

    private parentRouteId: number;

    constructor(
        private router: Router,
        private route: ActivatedRoute) {
    }

    ngOnInit() {
        this.sub = this.router.routerState.parent(this.route).params.subscribe(params => {
            this.parentRouteId = +params["id"];
        });
    }

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

In this scenario, the route follows the structure: /parent/:id/child/:childid

export const routes: RouterConfig = [
    {
        path: '/parent/:id',
        component: ParentComponent,
        children: [
            { path: '/child/:childid', component: ChildComponent }]
    }
];

Answer 6

Utilizing the "@angular/router": "3.0.0-alpha.6" library, I successfully retrieved the parent route argument by implementing the following method:

export class ChildComponent {

    private sub: any;

    private parentRouteId: number;

    constructor(
        private router: Router,
        private route: ActivatedRoute) {
    }

    ngOnInit() {
        this.sub = this.router.routerState.parent(this.route).params.subscribe(params => {
            this.parentRouteId = +params["id"];
        });
    }

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

In this scenario, the route follows the structure: /parent/:id/child/:childid

export const routes: RouterConfig = [
    {
        path: '/parent/:id',
        component: ParentComponent,
        children: [
            { path: '/child/:childid', component: ChildComponent }]
    }
];

Answer 7

Answer №4

If you use ActivatedRote and capture a snapshot, the process becomes even simpler:

constructor(private route: ActivatedRoute) {};
 ngOnInit() {
    console.log('checking the parent route parameter:',            this.route.snapshot.parent.params['PARAM-NAME']);
  }

Answer 8

If you use ActivatedRote and capture a snapshot, the process becomes even simpler:

constructor(private route: ActivatedRoute) {};
 ngOnInit() {
    console.log('checking the parent route parameter:',            this.route.snapshot.parent.params['PARAM-NAME']);
  }

Passing route parameters to child routes in Angular 2: A step-by-step guide

Answer №1

Answer №2

Answer №3

Answer №4

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