Angular routing

Angular routing is a feature that allows navigation between different views and components within a single-page application. Routing helps organize the application into multiple views, making it more manageable and easier to navigate. In this section, we will cover the basics of Angular routing, traditional routing, and lazy loading.

Basic Routing

In Angular, the routing module is responsible for managing the routes in the application. The module is imported from the @angular/router package, and it is added to the imports array in the @NgModule decorator. Here is an example of the basic routing setup:

import { NgModule } from '@angular/core';
import { RouterModule, Routes } from '@angular/router';
import { HomeComponent } from './home/home.component';
import { AboutComponent } from './about/about.component';

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

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

In this example, we have two components, HomeComponent and AboutComponent. We define the routes for these components using the Routes array. Each route is defined with a path property that maps to a URL, and a component property that maps to the component that should be displayed when the URL is navigated to. The RouterModule.forRoot() method is used to configure the routes in the application, and it is imported into the imports array of the @NgModule decorator.

 

Traditional Routing

Traditional routing is the process of loading an entire application when the user navigates to a new URL. In Angular, traditional routing can be achieved using the routerLink directive, which generates an a tag with the specified route. Here is an example of how to use the routerLink directive:

<a routerLink="/">Home</a> 
<a routerLink="/about">About</a>

In this example, we have two links that navigate to the home and about routes. When the links are clicked, the entire application is reloaded with the new component.

 

Lazy Loading

Lazy loading is the process of loading a component or module only when it is needed. This helps reduce the initial load time of the application, as not all components need to be loaded at once. In Angular, lazy loading can be achieved by defining a separate module for the component or set of components that need to be lazy loaded. Here is an example of how to use lazy loading:

import { NgModule } from '@angular/core';
import { RouterModule, Routes } from '@angular/router';
import { HomeComponent } from './home/home.component';

const routes: Routes = [
  { 
    path: '', 
    component: HomeComponent 
  },
  {
    path: 'about',
    loadChildren: () => import('./about/about.module').then((m) => m.AboutModule),
  },
];

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

In this example, we have defined the AboutComponent in a separate module called AboutModule. When the about route is navigated to, the AboutModule is lazily loaded using the loadChildren property of the route. The import() function is used to import the AboutModule, and the then() method is used to return the AboutModule after it has been loaded.

Lazy loading can greatly improve the performance of an application, especially for larger applications with many components.

 

In Angular, routing parameters are used to pass information between different views or components. There are several routing parameters that can be used to control the navigation behavior in an Angular application. Here are some of the most commonly used routing parameters:

Path parameters:

Path parameters are used to pass variable values in the URL path. For example, if you have a route with the path "/users/:id", you can retrieve the value of "id" by subscribing to the ActivatedRoute service. Here is an example of how to define a route with path parameters in the Angular router:

{
    path: 'users/:id', 
    component: UserComponent
}

 

Query parameters:

Query parameters are used to pass data to a route via the URL query string. For example, if you have a route with the path "/search", you can pass search parameters like this: "/search?q=keyword". Here is an example of how to define a route with query parameters in the Angular router: 

  { 
    path: 'search', 
    component: SearchComponent 
  }

 

CanActivate guard:

CanActivate is an interface that is used to check whether a user is allowed to activate a particular route. For example, you can use CanActivate to check whether a user is authenticated before allowing them to access a protected route. Here is an example of how to use CanActivate in the Angular router:

{ 
    path: 'dashboard', 
    component: DashboardComponent, 
    canActivate: [AuthGuard] 
}

 

Routing Guards Click here to see with example. 

 

CanDeactivate guard:

CanDeactivate is an interface that is used to check whether a user is allowed to deactivate a particular route. For example, you can use CanDeactivate to confirm whether a user really wants to leave a form that they are editing. Here is an example of how to use CanDeactivate in the Angular router:

  { 
    path: 'edit-profile', 
    component: EditProfileComponent, 
    canDeactivate: [ProfileGuard] 
  }

Routing Guards Click here to see with example. 

 

Resolve guard:

Resolve is an interface that is used to resolve data before activating a particular route. For example, you can use Resolve to load data from a backend server before displaying a view. Here is an example of how to use Resolve in the Angular router:

  { 
    path: 'user/:id', 
    component: UserComponent, 
    resolve: { 
      user: UserResolver 
    } 
  }

 

Routing Guards Click here to see with example. 

 

Children routes:

Children routes are used to create nested routes in Angular. For example, you can have a route "/admin" with children routes "/users" and "/products". Here is an example of how to define children routes in the Angular router:

  {
    path: 'admin',
    component: AdminComponent,
    children: [
      { 
        path: 'users', 
        component: UsersComponent 
      },
      { 
        path: 'products', 
        component: ProductsComponent 
      },
    ],
  },

These are some of the most commonly used routing parameters in Angular. By using these parameters, you can create complex navigation behaviors in your application, and make your application more dynamic and interactive.

 

Conclusion

Angular routing is a powerful feature that allows for efficient navigation between different views and components in a single-page application. Traditional routing can be used to load the entire application when a new URL is navigated to, while lazy loading can be used to load components or modules only when they are needed. By using these features, developers can create efficient and responsive Angular applications that provide a great user experience.