NestJS : cannot provide an instance to child module owning the interface - nestjs

Question

I try to decouple the controller module of a NestJs module from a domain module (as per clean architecture principles), so that dependency flows only to Domain.
I do not understand how to make it work, injection of the repo interface's implementation does not happen (error when nest starts).
Here is the module structure :
AppModule -> CommunityControllerModule -> DomainModule
(provides repoImpl (has service requiring an unknown
by token) concrete repo interface impl)
The CommunityControllerModule :
import { DomainModule } from 'libs/domain/src';
import { Module } from '#nestjs/common';
import { CommunityController } from './community.controller';
import { CommunityRepositoryImpl } from './community.repository';
#Module({
imports: [DomainModule, CommunityRepositoryImpl],
controllers: [CommunityController],
exports: [CommunityRepositoryImpl],
providers: [
{
provide: 'CommunityRepository',
useClass: CommunityRepositoryImpl,
},
],
})
export class CommunityControllerModule {}
The DomainModule :
import { Module } from '#nestjs/common';
import { CommunityService } from './community.service';
#Module({
providers: [CommunityService],
exports: [CommunityService],
})
export class DomainModule {}
The CommunityService where injection fails :
import { HttpException, HttpStatus, Inject, Injectable } from '#nestjs/common';
import { CommunityRepository } from './community.repo';
#Injectable()
export class CommunityService {
constructor(
#Inject('CommunityRepository') private repo: CommunityRepository,
) {}
}
The outputted error :
> nest start
webpack 5.28.0 compiled successfully in 8218 ms
[Nest] 7204 - 2021-05-05 20:52:05 [NestFactory] Starting Nest application...
[Nest] 7204 - 2021-05-05 20:52:05 [InstanceLoader] CommunityRepositoryImpl dependencies initialized +49ms
[Nest] 7204 - 2021-05-05 20:52:05 [ExceptionHandler] Nest can't resolve dependencies of the CommunityService (?). Please make sure that the argument CommunityRepository at index [0] is available in the DomainModule context.
Potential solutions:
- If CommunityRepository is a provider, is it part of the current DomainModule?
- If CommunityRepository is exported from a separate #Module, is that module imported within DomainModule?
#Module({
imports: [ /* the Module containing CommunityRepository */ ]
})

Answer 1

What I missed was to set the DomainModule as a dynamic module.
The Domain module becomes :
import { DynamicModule, Module } from '#nestjs/common';
import { CommunityService } from './community.service';
#Module({})
export class DomainModule {
static register(repoImpl): DynamicModule {
return {
module: DomainModule,
imports: [repoImpl],
providers: [
CommunityService,
{
provide: 'CommunityRepository',
useClass: repoImpl,
},
],
exports: [CommunityService],
};
}
}
...and the CommunityControllerModule imports it with the repo implementation :
import { DomainModule } from 'libs/domain/src';
import { Module } from '#nestjs/common';
import { CommunityController } from './community.controller';
import { CommunityRepositoryImpl } from './community.repository';
#Module({
imports: [
DomainModule.register(CommunityRepositoryImpl),
CommunityRepositoryImpl,
],
controllers: [CommunityController],
exports: [CommunityRepositoryImpl],
providers: [
{
provide: 'CommunityRepository',
useClass: CommunityRepositoryImpl,
},
],
})
export class CommunityControllerModule {}