How to add custom field?

[vickyRathee]

I'd like to add custom field in logs collection, but it's not written in DB. Any suggestion?

const metaFormat = winston.format((info) => {
  return { ...info, app: 'test' };
});

const transports  = [
              new winston.transports.MongoDB({
                db: process.env.MONGODB_CONNECTION,
                options: {
                  useUnifiedTopology: true,
                },
                collection: 'logs',
                format: winston.format.combine(
                  metaFormat(),
                  winston.format.json(),
                ),
              }),
            ]