How to Implement Routing with Multiple Modules in an Angular Application

In this post, we’ll dive into a common Angular scenario—implementing routing with multiple modules. In most applications, routing is managed within a single App Module.

However, as your app grows, you’ll often have multiple modules, each with its own components and routes.

In this guide, we’ll cover how to set up routing for different modules, focusing on the auth module.

Step 1: Understanding the Module Structure

Our application has several modules besides the App Module, including:

• Auth Module
• Public Module
• Shared Module
• Users Module

Each of these modules might have its own set of components, and they often need specific routes.

For this example, we’ll focus on the Auth Module. Our goal is to define routing paths such as:

• /auth/login
• /auth/signup

Step 2: Establishing a Relationship Between Modules

The first step is to establish a relationship between the App Module and the Auth Module. Here’s how:

1. Import the Auth Module into the App Module:
   We need to import the Auth Module into our App Module so that the app recognizes the routes and components inside the Auth Module.

   import { AuthModule } from './auth/auth.module';

   @NgModule({
     imports: [
       // Other imports
       AuthModule
     ],
     declarations: [
       // Components
     ],
     bootstrap: [AppComponent]
   })
   export class AppModule { }

2. Modify the App Routing Module:
   Now, in the app’s routing module, we can define routes for the Auth Module. We’ll specify paths like /auth/login and /auth/signup.

   const routes: Routes = [
     { 
       path: 'auth', 
       children: [
         { path: 'login', component: LoginComponent },
         { path: 'signup', component: SignupComponent }
       ]
     }
   ];

Step 3: Creating a Layout Component for the Auth Module

If you want the Auth Module to have a different layout from the main app (e.g., no header or footer), you can create a new layout component specific to this module.

To generate the component:

ng generate component auth/auth-layout --flat

Now, we can use this component to handle the layout for all routes within the Auth Module.

Step 4: Using Router Outlet for Nested Routes

In the Auth Layout Component, you’ll need a Router Outlet to display nested routes like login and signup. However, when we initially try to add a router outlet, we may run into an error:

<router-outlet></router-outlet>

If you encounter an error such as "router-outlet is not a known element", it means that the RouterModule has not been imported in the Auth Module. Let’s fix that.

Step 5: Importing Router Module in Auth Module

Go to the Auth Module file and make sure you import the RouterModule:

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

@NgModule({
  declarations: [/* Components */],
  imports: [
    RouterModule // Required for routing
  ]
})
export class AuthModule { }

Step 6: Final Testing

Once you’ve set up everything, go to the browser and test your routes:

• Navigate to /auth/login
• Navigate to /auth/signup

Both routes should work as expected. If you’re using a separate layout for the Auth Module, it will be displayed without affecting the main app’s layout.

Common Errors and Troubleshooting

1. Router Outlet Not Recognized: If the router outlet isn’t recognized, ensure that the RouterModule is imported in the correct module.
2. Routes Not Loading: Double-check that the module is imported in the App Module and that the paths are correctly defined.
3. Layouts Not Applying: If your custom layout isn’t showing up, ensure that it’s specified in the Auth Module’s routes and contains a router-outlet to load the nested components.

Conclusion

Handling routing across multiple modules in Angular might seem tricky at first, but once you understand how to connect modules and manage child routes, it becomes a lot easier.

By following these steps, you’ll be able to efficiently organize your application structure while keeping your routes modular and maintainable.

Let me know in the comments if you run into any issues or need further clarification!