Optional Registration using the ConfigModule about config

[jmcdo29]

Absolutely. I'll work on it this week

[kamilmysliwiec]

So basically you're suggesting that we could expose this helper type out of the box, as part of the @nestjs/config package:

export class ConditionalModule {
  static async registerWhen(moduleToRegister, condition) {
    await ConfigModule.envVariablesLoaded();
    return condition(process.env) 
         ? { module: ConditionalModule, imports: [moduleToRegister] 
         : { module: ConditionalModule, imports: [] }
  }
}

Example

imports: [ConditionalModule.registerWhen(ScheduleModule.forRoot(), ({ USE_CRON }) => ...)]

[jmcdo29]

Hmmm, I'm not quite sure how feasible that would be, as injecting a provider is usually for module configuration, not module registration, y'know? But as imports can have async values, we can make use of the existing method for waiting for process.env to be loaded and return the correct module. I do like the registerModule with the object rather than the two parameters though

[micalevisk]

can you show some code snippet on how it would looks like from consumer side?

[jmcdo29]

@Module({
  imports: [
    ConfigModule.forRoot(),
    ConfifgModule.optionallyRegisterModule(
      ScheduleModule.forRoot(),
      'USE_CRON'
    )
  ],
  ...
})
export class AppModule {}

OR

@Module({
  imports: [
    ConfigModule.forRoot(),
    ConfifgModule.optionallyRegisterModule(
      ScheduleModule.forRoot(),
      () => JSON.parse(process.env.USE_ENV)
    )
  ],
  ...
})
export class AppModule {}

[micalevisk]

I wonder if it couldn't be something that works on top of ConfigService:

@Module({
  imports: [
    ConfigModule.forRoot(),
    ConfigModule.registerModule({
      module: ScheduleModule.forRoot(),
      when: (configService: ConfigService) =>
        configService.get('USE_ENV') == true
    })
  ],
  ...
})
export class AppModule {}

[jmcdo29]

@kamilmysliwiec yep, that's generally it. Figured we'd make it a part of this package as it's very closely tied to the module

[kamilmysliwiec]

This would make a lot of sense indeed. Would you like to create a PR for this?

[jmcdo29]

Let's track this here