Module

A module is a class annotated with a @Module() decorator. The @Module() decorator provides metadata that Nest uses to organize the application structure.

Each application entrypoint requires at least one module. This module is the starting point for Nest to build the internal data structure. While very small applications may theoretically have just the one module, this is not the typical case. We want to emphasize that modules are strongly recommended as an effective way to organize your components. Thus, for most applications, the resulting architecture will employ multiple modules, each encapsulating a closely related set of capabilities.

The @Module() decorator takes a single object whose properties describe the module:

• imports: a list of modules whose exported providers are available for dependency injection in this module.
• controllers: controllers defined in this module which have to be instantiated.
• providers & exports: see dependency injection for more information.

We create a new module for use-case in our application. This will help us to keep our codebase clean and organized.

Example

@Module({
  imports: [
    TypeOrmModule.forFeature([Role]),
  ],
  controllers: [CreateRoleController],
  providers: [CreateRoleUseCase],
  exports: []
})
export class CreateRoleUseCaseModule {}

As you can see in the example above, we have created a CreateRoleUseCaseModule. This module imports the TypeOrmModule with the Role entity. This way, nestjs is able to inject the RoleRepository into the CreateRoleUseCase.

In the role folder, there will be a RoleModule that imports the CreateRoleUseCaseModule. This way, it is a bit cleaner when importing it into the API module.

@Module({
  imports: [
    CreateRoleModule,
  ]
})
export class RoleModule {}