Router module

Hint This chapter is only relevant to HTTP-based applications.

In an HTTP application (e.g., a REST API), the route path for a handler is determined by concatenating the (optional) prefix declared for the controller (inside the @Controller() decorator) and any path specified in the method's decorator (e.g., @Get('users')). You can learn more about this in the routing section of the controllers chapter. Additionally, you can define a global prefix for all routes registered in your application, or enable versioning.

In some cases, it's useful to define a prefix at the module level, which then applies to all controllers registered inside that module. For example, imagine a REST application that exposes several endpoints used by a specific part of your application called "Dashboard". Instead of repeating the /dashboard prefix in each controller, you can use the RouterModule, as follows:

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

Hint The RouterModule class is exported from the @nestjs/core package.

You can also define hierarchical structures, in which each module has children modules. The child modules inherit their parent's prefix. In the following example, the AdminModule is registered as the parent module of DashboardModule and MetricsModule:

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

Hint Use this feature carefully, as overusing it can make code difficult to maintain over time.

In the example above, every controller registered inside the DashboardModule gets an extra /admin/dashboard prefix, because the module concatenates paths recursively from top to bottom, parent to children. Likewise, every controller defined inside the MetricsModule gets the additional module-level prefix /admin/metrics.