Inject dependency to custom resolver

[Crismon96]

I want to implement some custom logic to default to a language saved in the DB for the user when the lang header is not provided. For this to work I need to inject the db-service into the resolver.
Nest, just keeps complaining that the service is not properly provided. Alternatively I could also set the language for the I18N context in a middleware (that is applied after the I18N middleware so I cant just set the header there) but the context does not seem to have an option to set the language. Thats why I think a custom resolver is the only proper solution.

This is my current implementation:
app.module.ts

@Module({
  imports: [
    I18nModule.forRoot({
        fallbackLanguage: 'en-GB',
        loaderOptions: {
          path: join(__dirname, '../../../libs/i18n/backend/src/locales'),
        },
        typesOutputPath: join(__dirname, '../../../../src/generated/i18n.generated.ts'),
      resolvers: [
        GraphQLWebsocketResolver,
        { use: QueryResolver, options: ['lang'] },
        AcceptLanguageResolver,
        // eslint-disable-next-line @typescript-eslint/ban-ts-comment
        // @ts-ignore
        {
          // with use I get an error that the service is not provided, without use I get an type error and "resolver.resolve is not a function" when the resolver is called.
          // use: I18NCustomHeaderResolver,
          useFactory: (databaseService) => new I18NCustomHeaderResolver(['x-lang'], databaseService),
          inject: [DatabaseService],
        },
      ],
    }),

The whole configuration was valid and works. Its just the databaseService that I can not provide to the custom resolver.

languageResolver.ts: really just the custom db logic with the injected service

@Injectable()
export class I18NCustomHeaderResolver implements I18nResolver {
  private logger = new Logger('I18nService');
  constructor(
    @I18nResolverOptions()
    private keys: string[] = [],
    private readonly dbService: DatabaseService,
  ) {
    console.log('dbService: ', dbService);
  }

  resolve(context: ExecutionContext) {
    let req: any;

    switch (context.getType() as string) {
      case 'http':
        req = context.switchToHttp().getRequest();
        break;
      case 'graphql':
        [, , { req }] = context.getArgs();
        break;
    }

    let lang: string;

    if (req) {
      for (const key of this.keys) {
        if (key === 'accept-language') {
          this.logger.warn(
            'HeaderResolver does not support RFC4647 Accept-Language header. Please use AcceptLanguageResolver instead.',
          );
        }
        if (req.headers !== undefined && req.headers[key] !== undefined) {
          lang = req.headers[key];
          break;
        }
      }
    }

   ... HERE IS MY DB LOGIC, nothing special
  
    return lang;
  }
}

Can you please give me hint how I can inject my service to the custom provider and what is an recommended pattern. Unfortunately documentation is missing for these kind of use cases.