[Angular2 Router] Auxiliary Routes bit by bit

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Auxiliary Routes is is little bit hard to understand. 

Here is demo, link

You can see each category has an own 'View detials' button, and there is a side menu on the right side.

What we want is when we click the "View details" button, it will nav to category detail component along with the id (in this case is the title ex: 'development'). 

Also we want the side menu also get the information what button have been clicked. 

Vice Versa....

Once we got those id, then we can do the rest application logic, which won't be included here... but the importantce is to get the id for both category detail component and sidemenu component.

The router config:

export const routerConfig: Routes = [
    {
        path: 'home',
        component: HomeComponent
    },
    {
        path: 'courses',
        component: CoursesComponent,
        children: [
            {
                path: '',
                component: CourseCardsComponent
            },
            {
              path: ':id',
              component: CoursesCategoryComponent
            },
            {
                path: '',
                outlet: 'sidemenu',
                component: SideMenuComponent
            },
            {
                path: ':id',
                outlet: 'sidemenu',
                component: SideMenuComponent
            }
        ]
    },
    {
        path: '',
        redirectTo: '/home',
        pathMatch: 'full'
    },
    {
        path: '**',
        redirectTo: '/home',
        pathMatch: 'full'
    }
];

Look at 'courses' router, we have two empty paths, it means for the empty path, we have tow componet to display,  one is 'CourseCardsComponent' and 'SidemenuComponent'. 'CourseCardsComponent' will be displayed in primay outlet, and 'SidemenuComponent' will be display in auxiliary router outlet.

<main>
    <div class="container">
        <div class="row row-offcanvas row-offcanvas-right">
            <div class="col-xs-12 col-sm-9">
                <ol class="breadcrumb">
                    <li class="breadcrumb-item"><a routerLink="/home">Home</a></li>
                    <li class="breadcrumb-item active">Courses</li>
                </ol>
                <div class="jumbotron">
                    <h1>Course Categories!</h1>
                    <p>This is a list of course categories, click on each to see a list of courses for a given
                        category.</p>
                </div>
                <router-outlet></router-outlet>
            </div>
            <router-outlet name="sidemenu"></router-outlet>
        </div>
    </div>
</main>

So now when we click the button, how to make url like this:

/courses/(development//sidemenu:development)

and what does it means?

This url means:

• the courses url segment is active

• inside it the primary route is set to /courses/development

• the auxiliary child route 'development' is active for the outlet sidemenu

So there are two thing going on, for the primay outlet, we are in /courses/development state, and for sidemenu, we are also in /development state. 

import { Component, OnInit } from '@angular/core';
import {Router, ActivatedRoute} from "@angular/router";

@Component({
  selector: 'app-course-cards',
  templateUrl: './course-cards.component.html',
  styleUrls: ['./course-cards.component.css']
})
export class CourseCardsComponent {

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

    navigate(path) {
        this.router.navigate([{outlets: {primary: path, sidemenu:path}}], {relativeTo: this.route});
    }
}

    <div class="col-xs-6 col-lg-4">
        <h2>Development</h2>
        <p>Donec id elit non mi porta gravida at eget metus. Fusce dapibus, tellus ac cursus commodo, tortor mauris condimentum nibh, ut fermentum massa justo sit amet risus. Etiam porta sem malesuada magna mollis euismod. Donec sed odio dui. </p>
        <p><a class="btn btn-secondary" (click)="navigate('development')"  role="button">View details »</a></p>
    </div>

So we are using 'navigate' method or Router, set primary and auxiliary router's path to 'development'. 

How to get the path information in sidemenu and category detail?

  id: string;
  constructor(route: ActivatedRoute, private router: Router) {
    route.params.subscribe(
        (params) => this.id = params['id']
    )
  }

Until now, when we click the "View details" button, we can finish the logic, then let's see how it is done from sidemenu.

<div class="col-xs-6 col-sm-3 sidebar-offcanvas" id="sidebar">
    <h2>{{id}}</h2>
    <div class="list-group">
        <a (click)="nav($event, 'development')" class="list-group-item">Development</a>
        <a href="#" (click)="nav($event, 'it-software')" class="list-group-item">IT &
            Software</a>
        <a href="#" (click)="nav($event, 'office')" class="list-group-item">Office
            Productivity</a>
        <a href="#" (click)="nav($event, 'photo')" class="list-group-item">Photography</a>
        <a href="#" (click)="nav($event, 'health')" class="list-group-item">Health and
            Fitness</a>
        <a href="#" (click)="nav($event, 'music')" class="list-group-item">Music</a>
    </div>
</div>

  nav(e, path){
    e.preventDefault();
    this.router.navigateByUrl(`/courses/(${path}//sidemenu:${path})`);
  }

Pretty simple and similar, just using navigateByUrl method, cause here we want to use absoulte router.