Overview

• Concept of Routing in NestJS
• 1- Basic Routing:
• 2- Global Prefix:
• Router Module Usage
• 1- Module-Level Prefixes:
• 2- Example with DashboardModule:
• 3- Hierarchical Structures:
• 4- Hierarchical Structures:

Certainly! Let's break down the section about the Router module in NestJS, which is specifically relevant for HTTP-based applications like REST APIs.

Concept of Routing in NestJS

1- Basic Routing:

• In NestJS, routes for HTTP handlers (like those in controllers) are defined by combining the path specified in the controller's @Controller decorator and the path in the method's decorator (like @Get, @Post, etc.). For example, a @Get('users') in a controller with @Controller('api') will result in the route /api/users.

2- Global Prefix:

• You can set a global prefix for all routes in your application. This is useful for versioning or segmenting the API at a high level.

Router Module Usage

1- Module-Level Prefixes:

• Sometimes, it's useful to define a prefix at the module level, especially when you have a group of routes that belong to a specific part of your application, like "Dashboard".
• Instead of repeating the /dashboard prefix in each controller, you can use the RouterModule to set a prefix for all routes within a module.

2- Example with DashboardModule:

• In your AppModule, you can import DashboardModule and use RouterModule.register() to associate a path with the module.
• The RouterModule allows you to define that all routes within DashboardModule should be prefixed with /dashboard.

@Module({
  imports: [
    DashboardModule,
    RouterModule.register([
      {
        path: 'dashboard',
        module: DashboardModule,
      },
    ]),
  ],
})
export class AppModule {}

3- Hierarchical Structures:

• NestJS allows for hierarchical routing, where modules can have child modules, inheriting the parent's prefix.
• For instance, if you have an AdminModule that includes DashboardModule and MetricsModule, you can structure routes hierarchically.

4- Hierarchical Structures:

• You can define AdminModule as a parent module and DashboardModule and MetricsModule as children.
• Routes in DashboardModule will then have the prefix /admin/dashboard, and routes in MetricsModule will have /admin/metrics.

@Module({
  imports: [
    AdminModule,
    DashboardModule,
    MetricsModule,
    RouterModule.register([
      {
        path: 'admin',
        module: AdminModule,
        children: [
          {
            path: 'dashboard',
            module: DashboardModule,
          },
          {
            path: 'metrics',
            module: MetricsModule,
          },
        ],
      },
    ])
  ],
})

Conclusion The Router module in NestJS is a powerful feature for organizing and structuring routes in your application. It allows for setting module-level prefixes and creating hierarchical route structures, making it easier to manage complex route setups. However, it's important to use this feature judiciously to maintain clarity and simplicity in your codebase. Overusing hierarchical routing or deep nesting can make the code difficult to maintain and understand.