Child routes and nested routing in Angular

Introduction

Child routes let you organize your app's pages inside other pages. It helps keep things neat and easy to navigate.

You want a main page with smaller pages inside it, like a dashboard with tabs.

You need to show different content areas without leaving the main page.

You want to reuse a layout and just change parts inside it.

You want URLs that reflect the page hierarchy, like /products and /products/details.

You want to load parts of your app only when needed to save loading time.

Syntax

Angular

const routes: Routes = [
  {
    path: 'parent',
    component: ParentComponent,
    children: [
      { path: 'child1', component: Child1Component },
      { path: 'child2', component: Child2Component }
    ]
  }
];

The children array holds the nested routes inside a parent route.

The parent component should have a <router-outlet> where child routes show up.

Examples

This sets up a dashboard page with two child pages: stats and reports.

Angular

const routes: Routes = [
  {
    path: 'dashboard',
    component: DashboardComponent,
    children: [
      { path: 'stats', component: StatsComponent },
      { path: 'reports', component: ReportsComponent }
    ]
  }
];

Here, the products page shows a list by default and details when an ID is in the URL.

Angular

const routes: Routes = [
  {
    path: 'products',
    component: ProductsComponent,
    children: [
      { path: '', component: ProductListComponent },
      { path: ':id', component: ProductDetailComponent }
    ]
  }
];

Sample Program

This example shows a parent page with two child pages. The parent has links to switch between child1 and child2. The child content appears inside the parent's <router-outlet>.

When you open the app, it redirects to 'parent/child1' by default.

Angular

import { Component } from '@angular/core';
import { RouterModule, Routes } from '@angular/router';

@Component({
  selector: 'app-parent',
  template: `
    <h2>Parent Page</h2>
    <nav>
      <a routerLink="child1" aria-label="Go to Child 1">Child 1</a> |
      <a routerLink="child2" aria-label="Go to Child 2">Child 2</a>
    </nav>
    <router-outlet></router-outlet>
  `
})
export class ParentComponent {}

@Component({
  selector: 'app-child1',
  template: `<p>This is Child 1 content.</p>`
})
export class Child1Component {}

@Component({
  selector: 'app-child2',
  template: `<p>This is Child 2 content.</p>`
})
export class Child2Component {}

@Component({
  selector: 'app-root',
  template: `<router-outlet></router-outlet>`
})
export class AppComponent {}

const routes: Routes = [
  {
    path: 'parent',
    component: ParentComponent,
    children: [
      { path: 'child1', component: Child1Component },
      { path: 'child2', component: Child2Component }
    ]
  },
  { path: '', redirectTo: 'parent/child1', pathMatch: 'full' }
];

import { NgModule } from '@angular/core';
import { BrowserModule } from '@angular/platform-browser';

@NgModule({
  declarations: [AppComponent, ParentComponent, Child1Component, Child2Component],
  imports: [BrowserModule, RouterModule.forRoot(routes)],
  bootstrap: [AppComponent]
})
export class AppModule {}

Important Notes

Always put <router-outlet> in the parent component template to show child routes.

Use routerLink for navigation links to keep the app fast and smooth.

Child routes help keep URLs clean and show the app structure clearly.

Summary

Child routes let you nest pages inside other pages for better organization.

The parent component needs a <router-outlet> to display child content.

Use child routes to create layouts with changing parts and clear URLs.

Practice

1. What is the main purpose of child routes in Angular routing?

easy

A. To replace the main router outlet completely

B. To disable navigation between pages

C. To load components without URLs

D. To nest pages inside other pages for better organization

Solution

1. Step 1: Understand child routes concept

   Child routes allow nesting routes inside a parent route to organize pages hierarchically.

2. Step 2: Compare options with concept

   Only To nest pages inside other pages for better organization correctly describes this purpose; others are incorrect or unrelated.

3. Final Answer:

   To nest pages inside other pages for better organization -> Option D

4. Quick Check:

   Child routes = Nested pages [OK]

Hint: Child routes organize nested pages inside parents [OK]

Common Mistakes:

• Thinking child routes replace main router outlet
• Believing child routes work without URLs
• Confusing child routes with disabling navigation

2. Which syntax correctly defines a child route in Angular's RouterModule?

easy

A. { path: 'parent', children: ChildComponent }

B. { path: 'parent/child', component: ChildComponent }

C. { path: 'parent', children: [{ path: 'child', component: ChildComponent }] }

D. { path: 'parent', component: ParentComponent, child: [{ path: 'child' }] }

Solution

1. Step 1: Recall child route syntax

   Child routes are defined inside a 'children' array property of a route object.

2. Step 2: Match syntax with options

   { path: 'parent', children: [{ path: 'child', component: ChildComponent }] } correctly uses 'children' with an array of child route objects; others misuse properties or structure.

3. Final Answer:

   { path: 'parent', children: [{ path: 'child', component: ChildComponent }] } -> Option C

4. Quick Check:

   Child routes use 'children' array [OK]

Hint: Child routes go inside 'children' array in route config [OK]

Common Mistakes:

• Using 'child' instead of 'children'
• Defining child path as 'parent/child' in one route
• Assigning component directly to 'children'

3. Given this route config:

{ path: 'dashboard', component: DashboardComponent, children: [ { path: 'stats', component: StatsComponent } ] }

What happens when navigating to /dashboard/stats?

medium

A. Only StatsComponent loads, DashboardComponent is ignored

B. DashboardComponent loads with StatsComponent displayed inside its router-outlet

C. DashboardComponent loads but StatsComponent does not display

D. Navigation fails with an error

Solution

1. Step 1: Understand nested route rendering

   Child routes render their components inside the parent's <router-outlet>.

2. Step 2: Apply to given URL

   At /dashboard/stats, DashboardComponent loads first, then StatsComponent loads inside its router-outlet.

3. Final Answer:

   DashboardComponent loads with StatsComponent displayed inside its router-outlet -> Option B

4. Quick Check:

   Child route renders inside parent component [OK]

Hint: Child shows inside parent's router-outlet on nested URL [OK]

Common Mistakes:

• Expecting child component to replace parent
• Forgetting to add router-outlet in parent
• Assuming navigation error without cause

4. Identify the error in this route config:

{ path: 'home', component: HomeComponent, children: { path: 'profile', component: ProfileComponent } }

medium

A. 'children' should be an array, not an object

B. Missing component for 'home' route

C. 'path' cannot be used inside children

D. ProfileComponent must be declared in AppModule

Solution

1. Step 1: Check 'children' property type

   The 'children' property must be an array of route objects, not a single object.

2. Step 2: Verify given config

   Here, 'children' is incorrectly assigned an object instead of an array.

3. Final Answer:

   'children' should be an array, not an object -> Option A

4. Quick Check:

   'children' = array of routes [OK]

Hint: 'children' must always be an array, not a single object [OK]

Common Mistakes:

• Using object instead of array for children
• Confusing 'path' usage inside children
• Assuming missing component causes this error

5. You want to create a nested route where /settings loads SettingsComponent and /settings/profile loads ProfileComponent inside it. Which setup is correct?

hard

A. Define { path: 'settings', component: SettingsComponent, children: [{ path: 'profile', component: ProfileComponent }] } and add <router-outlet> in SettingsComponent template

B. Define { path: 'settings/profile', component: ProfileComponent } only, no children needed

C. Define { path: 'settings', component: ProfileComponent, children: [{ path: 'profile', component: SettingsComponent }] }

D. Define { path: 'settings', component: SettingsComponent } and load ProfileComponent manually inside SettingsComponent without routing

Solution

1. Step 1: Setup nested routes properly

   To nest ProfileComponent inside SettingsComponent, use 'children' array with ProfileComponent route.

2. Step 2: Ensure parent template has router-outlet

   SettingsComponent template must include <router-outlet> to display child routes.

3. Final Answer:

   Define { path: 'settings', component: SettingsComponent, children: [{ path: 'profile', component: ProfileComponent }] } and add <router-outlet> in SettingsComponent template -> Option A

4. Quick Check:

   Nested route + router-outlet = correct setup [OK]

Hint: Parent needs router-outlet and children array for nested routes [OK]

Common Mistakes:

• Defining nested path as one string without children
• Swapping parent and child components
• Not adding router-outlet in parent component