RouterModule configuration in Angular - Mini Project: Build & Apply

RouterModule configuration

📖 Scenario: You are building a simple Angular app with navigation between two pages: Home and About.Users should be able to click links to switch pages without reloading the browser.

🎯 Goal: Create a basic Angular RouterModule setup with two routes: '' for HomeComponent and 'about' for AboutComponent.Configure the router in the main app module.

📋 What You'll Learn

Create a routes array with two routes: path '' for HomeComponent and path 'about' for AboutComponent

Create a variable called routes to hold the routes array

Import RouterModule and configure it with RouterModule.forRoot(routes)

Add RouterModule to the imports array of the @NgModule decorator

💡 Why This Matters

🌍 Real World

Routing is essential in Angular apps to create multi-page experiences without full page reloads, improving user experience.

💼 Career

Understanding RouterModule configuration is a key skill for Angular developers working on real-world web applications with navigation.

1

Create routes array

Create a constant called routes that is an array with two route objects: one with path: '' and component: HomeComponent, and another with path: 'about' and component: AboutComponent.

Angular

# Create a constant called routes with two route objects
# Your code here

Hint

Use const routes = [ ... ] with two objects inside.

2

Import RouterModule and configure

Import RouterModule from @angular/router and create a constant called appRoutingModule that calls RouterModule.forRoot(routes).

Angular

const routes = [
  { path: '', component: HomeComponent },
  { path: 'about', component: AboutComponent }
];

// Import RouterModule and create appRoutingModule
# Your code here

Hint

Use import { RouterModule } from '@angular/router'; and then const appRoutingModule = RouterModule.forRoot(routes);

3

Add RouterModule to NgModule imports

In the @NgModule decorator, add appRoutingModule to the imports array.

Angular

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

const routes = [
  { path: '', component: HomeComponent },
  { path: 'about', component: AboutComponent }
];

const appRoutingModule = RouterModule.forRoot(routes);

@NgModule({
  declarations: [AppComponent, HomeComponent, AboutComponent],
  imports: [BrowserModule],  // Add appRoutingModule here
  bootstrap: [AppComponent]
})
export class AppModule { }

Hint

Make sure appRoutingModule is inside the imports array.

4

Add router-outlet to AppComponent template

In the AppComponent template, add the <router-outlet></router-outlet> tag to display routed components.

Angular

 tag inside AppComponent template -->

Hint

Use the <router-outlet></router-outlet> tag exactly inside the template.

Practice

1. What is the main purpose of RouterModule.forRoot(routes) in an Angular app?

easy

A. To create a new Angular component

B. To configure the app's routes and enable navigation based on URL paths

C. To style the app's components

D. To fetch data from a server

Solution

1. Step 1: Understand RouterModule role

   RouterModule is used to manage navigation and views based on URL paths in Angular.

2. Step 2: Role of forRoot method

   The forRoot method sets up the routes for the whole app, telling Angular which component to show for each path.

3. Final Answer:

   To configure the app's routes and enable navigation based on URL paths -> Option B

4. Quick Check:

   RouterModule.forRoot sets routes [OK]

Hint: Remember: forRoot sets main routes once per app [OK]

Common Mistakes:

• Confusing forRoot with creating components
• Thinking RouterModule styles components
• Assuming it fetches data

2. Which of the following is the correct syntax to import RouterModule with routes in an Angular module?

easy

A. RouterModule(routes)

B. imports: RouterModule.forRoot(routes)

C. imports: [RouterModule.forRoot(routes)]

D. RouterModule.import(routes)

Solution

1. Step 1: Check Angular module imports syntax

   Angular modules expect an array for the imports property.

2. Step 2: Correct use of RouterModule.forRoot

   RouterModule.forRoot(routes) returns a module configured with routes and must be inside an array.

3. Final Answer:

   imports: [RouterModule.forRoot(routes)] -> Option C

4. Quick Check:

   Imports must be an array with forRoot call [OK]

Hint: Always wrap RouterModule.forRoot in an array for imports [OK]

Common Mistakes:

• Omitting the array brackets in imports
• Using RouterModule.import which doesn't exist
• Calling RouterModule as a function directly

3. Given this route configuration:

const routes = [
  { path: '', component: HomeComponent },
  { path: 'about', component: AboutComponent }
];

What component will Angular display when the URL path is /about?

medium

A. AboutComponent

B. HomeComponent

C. No component, shows error

D. Both HomeComponent and AboutComponent

Solution

1. Step 1: Match URL path to route

   The URL path '/about' matches the route with path 'about'.

2. Step 2: Identify component for matched route

   The route with path 'about' uses AboutComponent.

3. Final Answer:

   AboutComponent -> Option A

4. Quick Check:

   Path '/about' shows AboutComponent [OK]

Hint: Match URL path exactly to route path to find component [OK]

Common Mistakes:

• Assuming empty path '' matches '/about'
• Thinking multiple components show at once
• Expecting error for valid path

4. Identify the error in this RouterModule configuration:

const routes = [
  { path: 'home', component: HomeComponent },
  { path: 'profile' component: ProfileComponent }
];

@NgModule({
  imports: [RouterModule.forRoot(routes)],
  exports: [RouterModule]
})
export class AppRoutingModule {}

medium

A. Routes array should be inside imports array

B. RouterModule.forRoot should be RouterModule.forChild

C. AppRoutingModule should not export RouterModule

D. Missing comma between 'profile' path and component property

Solution

1. Step 1: Check routes array syntax

   Between 'path: 'profile'' and 'component: ProfileComponent' a comma is missing, causing syntax error.

2. Step 2: Verify RouterModule usage and exports

   Using RouterModule.forRoot(routes) and exporting RouterModule is correct here.

3. Final Answer:

   Missing comma between 'profile' path and component property -> Option D

4. Quick Check:

   Comma missing in object properties causes error [OK]

Hint: Check commas between object properties in routes [OK]

Common Mistakes:

• Confusing forRoot and forChild usage
• Placing routes array incorrectly
• Removing exports of RouterModule

5. You want to add a default route that redirects empty path '' to '/home' using RouterModule. Which configuration is correct?

hard

A. { path: '', redirectTo: '/home', pathMatch: 'full' }

B. { path: '', redirectTo: 'home' }

C. { path: '', component: HomeComponent, redirectTo: '/home' }

D. { redirectTo: '/home', path: '', pathMatch: 'prefix' }

Solution

1. Step 1: Understand redirectTo usage

   To redirect from '' path, use redirectTo with full path and specify pathMatch as 'full' to match exact empty path.

2. Step 2: Check options for correct syntax

   { path: '', redirectTo: '/home', pathMatch: 'full' } correctly uses redirectTo with '/home' and pathMatch: 'full'. { path: '', redirectTo: 'home' } misses pathMatch, C wrongly combines component and redirectTo, D uses 'prefix' which causes partial matching issues.

3. Final Answer:

   { path: '', redirectTo: '/home', pathMatch: 'full' } -> Option A

4. Quick Check:

   Redirect empty path with pathMatch 'full' [OK]

Hint: Use pathMatch: 'full' when redirecting empty path [OK]

Common Mistakes:

• Omitting pathMatch property
• Combining component with redirectTo
• Using pathMatch: 'prefix' for empty path redirect