feat: allow adding providers when the module is loaded asynchronously

[jevillard]

PR Checklist

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• The commit message follows our guidelines: https://github.com/nestjs/nest/blob/master/CONTRIBUTING.md
• Tests for the changes have been added (for bug fixes / features)
• Docs have been added / updated (for bug fixes / features)

PR Type

What kind of change does this PR introduce?

• Bugfix
• Feature
• Code style update (formatting, local variables)
• Refactoring (no functional changes, no api changes)
• Build related changes
• CI related changes
• Other... Please describe:

It may be a bug fix or a feature, I'm not sure how you consider this PR

What is the current behavior?

Today, when calling the forRootAsync function, it is not possible to define your own providers if necessary

Issue Number: N/A

What is the new behavior?

Here is an example in one of my projects where I want to encapsulate the declaration of the TypeOrmModule module in my own DatabaseModule module so as not to repeat the declaration of my logger or other common options several times. This module is at the root of my Git repository and is used in different NestJS applications that I have in this same Git repository

• database.module.ts

export type DatabaseModuleOptions = TypeOrmModuleOptions
export type DatabaseModuleAsyncOptions = Pick<ModuleMetadata, 'imports'> & {
  useFactory: (
    ...args: any[]
  ) => DatabaseModuleOptions | Promise<DatabaseModuleOptions>;
  inject?: any[];
};

@Module({})
export class DatabaseModule {
  static forRootAsync(options: DatabaseModuleAsyncOptions): DynamicModule {
    return {
      module: DatabaseModule,
      imports: [
        TypeOrmModule.forRootAsync({
          imports: options.imports,
          providers: [
            {
              provide: 'DATABASE_MODULE_OPTIONS',
              useFactory: options.useFactory,
              inject: options.inject,
            },
          ],
          inject: ['DATABASE_MODULE_OPTIONS', PinoLogger],
          useFactory: (options: DatabaseModuleOptions, logger: PinoLogger) => ({
            ...options,
            loggerLevel: 'debug',
            logger: new TypeOrmLogger(logger),
            entities: [ // ...],
          }),
        } as TypeOrmModuleAsyncOptions),
      ],
      exports: [TypeOrmModule],
    };
  }

• foo.app.module.ts

@Module({
  imports: [
    DatabaseModule.forRootAsync({
      imports: [ConfigModule],
      useFactory: (configService: ConfigService) => ({
        ...configService.get('app.database.foo'),
      }),
      inject: [ConfigService],
    }),
  ]
})

Does this PR introduce a breaking change?

• Yes
• No

Other information

What do you think of this modification to allow to simply add providers?

[jevillard]

Anybody to review this little PR 😁 ?
Thanks 😄

[jmcdo29]

If I'm understanding this right, this would be a new approach to this problem, correct?

[jevillard]

Yes exactly.

We could also use the principle of the HttpModule of NestJS which in its asynchronous options offers an optional parameter called extraProviders?: Provider[].
What do you think about?

[kamilmysliwiec]

Yeah if we can rename it to extraProviders that would be great (to remain consistent with other packages)

[jevillard]

Ok it's done, we can now pass additional providers with the extraProviders attribute

[jevillard]

I think you can merge this PR and release a new minor version of the package. Or do you want to add something else?

[jevillard]

Up please 😃
With the 3 approvals, I think we can merge this MR.