[Fixed] ActivatedRoute subscribe to first child parameters observer


I’m not sure if this is the best way to implement this. If you have other opinions please share.

I have to implement a multi inbox system where the user can have multiple emails grouped by different inboxes.

For example: http://localhost/inbox/personal/ will show a list of emails in personal inbox, http://localhost/inbox/business/3 will show a list of emails in business inbox and will highlight email with id: 3

Routes look like this:

const routes: Routes = [
    path: '',
    pathMatch: 'full',
    redirectTo: 'personal' // redirect to personal inbox
    path: ':inbox',
    component: InboxContentComponent, // list of emails in :inbox
    children: [
        path: '',
        component: InboxNoSelectedEmailComponent, // no email selected
        path: ':id',
        component: InboxSelectedEmailComponent, // show selected email content

My problem is with InboxContentComponent . I need to detect when inbox changes and if an email is selected or not

  constructor(private route: ActivatedRoute) {
  ngOnInit() {
    this.route.paramMap.subscribe(inbox => {
      console.log('inbox', inbox);

Events are emitted only when inbox changes and not when email changes.
Is there a way to detect when child route parameters changes?

Doing this this.route.firstChild.paramMap.subscribe(); only works if on component initialization the route has a first child. if the route is like this http://localhost/inbox/business/ then this.route.firstChild is null

On solution I could think is to define routes like this

    path: ':inbox/:id',
    component: InboxContentComponent

and then check in InboxContentComponent if :id is set or not

Any ideas?


To tackle this kind of problem, I would listen to router events and retrieve what I want. Something like this :

import { Router, ActivatedRoute, NavigationEnd } from '@angular/router';
import { filter, map, mergeMap, tap } from 'rxjs/operators';

// ...
    // ...
    private activatedRoute: ActivatedRoute,
    private router: Router
  ) {
      filter((event) => event instanceof NavigationEnd),
      map(() => this.activatedRoute),
      map((route) => {
        while (route.firstChild) route = route.firstChild;
        return route;
      mergeMap((route) => route.paramMap),
        paramMap => console.log('ParamMap', paramMap)
      (paramAsMap) => // Get the params (paramAsMap.params) and use them to highlight or everything that meet your need 

You can adapt this to your need. Params ? Highlight : NoHighlight.

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