How to implement logging on nestjs?

[liunianbunian]

Prisma Example:

const prisma = new PrismaClient({
  log: [
    { level: 'warn', emit: 'event' },
    { level: 'info', emit: 'event' },
    { level: 'error', emit: 'event' },
  ],
})

prisma.$on('warn', (e) => {
  console.log(e)
})

MyDemo:

export class PrismaProvider extends PrismaClient implements OnModuleInit {
  constructor() {
    super({
      log: [
        { level: 'query', emit: 'event' },
        { level: 'warn', emit: 'event' },
        { level: 'info', emit: 'event' },
        { level: 'error', emit: 'event' },
      ],
    });
  }

  async onModuleInit() {
    await this.$connect();
  }

  async enableShutdownHooks(app: INestApplication) {
    this.$on('info', (e) => {
      console.log(e);
    });

    this.$on('beforeExit', async () => {
      await app.close();
    });
  }
}

but...
error TS2345: Argument of type '"info"' is not assignable to parameter of type '"beforeExit"'.

[Alex Ruheni]

Hey,

I created a small snippet you could use to log Prisma Client events on your console. In the example:

1. I've provided PrismaClientOptions as a generic and the query events that would be made available to the service
2. I then extended the default logger from Nestjs to label the service's events
3. The service can then logs out the query events whenever Prisma Client is initialized in onModuleInit. You can define more query events in there such as info, warn and error.

I'm not experienced with NestJs but this worked for me. I could be wrong. Feel free to correct me if I am. 🙂

import { Injectable, OnModuleInit, INestApplication, Logger } from '@nestjs/common'
import { Prisma, PrismaClient } from '@prisma/client'

@Injectable()
export class PrismaService extends PrismaClient<Prisma.PrismaClientOptions, 'query' | 'error' | 'info' | 'warn'>
  implements OnModuleInit {
  private readonly logger = new Logger(PrismaService.name);

  constructor() {
    super({
      log: [
        { level: 'query', emit: 'event' },
        { level: 'warn', emit: 'event' },
        { level: 'info', emit: 'event' },
        { level: 'error', emit: 'event' },
      ],
    });

  }

  async onModuleInit() {
    this.$on('query', (event) => {
      this.logger.log(event);
    });

    /**
     * define other query events here
     */
    await this.$connect();
  }

  async enableShutdownHooks(app: INestApplication) {
    this.$on('beforeExit', async () => {
      await app.close();
    });
  }
}

I hope this helps. Don't hesitate to reach out if you have any further questions on the subject.