How to validate mongo connection string in nestjs

Question

I have this MongoDataServicesModule:

@Module({
  imports: [
    MongooseModule.forFeature([{ name: CatModel.name, schema: UrlSchema }]),
    ConfigModule.forRoot(),
    MongooseModule.forRoot(process.env.MONGO_CONNECTION_STRING),
  ],
  providers: [{ provide: IDataServices, useClass: MongoDataServices }],
  exports: [IDataServices],
})
export class MongoDataServicesModule {}

What I would like to do is validate the connection string.

I used a little bit different layout in my old projects but now I decided to give another one a try and it got me thinking of how to do validation here the right way.

Answer 1

You can validate it inside useFacatory method - Here is a simple example of how to validate -

MongooseModule.forRootAsync({
      useFactory: () => {
        let mongoConnectionString = '';
        try {
          const args = process.argv.slice(2)[0];
          mongoConnectionString = args.split('--db=')[1];
        } catch (error) {
          console.error(
            'error fetching mongoDB string from args, should be passed --db=mongodb://localhost:27017/nextgen-promo',
            error,
          );
          process.exit(1);
        }
        console.log(`connecting to database: ${mongoConnectionString}`);
        return { uri: mongoConnectionString };
      },
    }),