NestJS example needed

[kdawgwilk]

Prisma extensions are fairly new and there are not many examples of how to use them with the NestJS framework. I think this official extension would be a great place to have some documentation on how you could use this extension with NestJS.

[Bonafede]

On nestjs we usually call PrismaService that is automatically injected globally on the framework. For me i didn't use this extension and just create a PrismaReadservice

import { Injectable } from '@nestjs/common';
import { Prisma, PrismaClient } from '@prisma/client';
import { logger } from '../logger/logger';

@Injectable()
export class PrismaReadService extends PrismaClient<
  Prisma.PrismaClientOptions,
  'query' | 'info' | 'warn' | 'error'
> {
  constructor() {
    let dbReadUrl = process.env.DATABASE_READ_URL;

    if (!dbReadUrl) {
        throw new Error('NO DATABASE URL DEFINED');
    }

    super({
      datasourceUrl: dbReadUrl
    });
  }
}

So i just use it as prismaService for write and PrismaReadService. It works but is not like this extension.

@Injectable()
export class AuthService {
  constructor(
    private readonly prisma: PrismaService,
    private readonly prismaRead: PrismaReadService,

Ofc will your responsibility in your code to not using read service for writing something, the code will not complain.

[paulopgss]

On nestjs we usually call PrismaService that is automatically injected globally on the framework. For me i didn't use this extension and just create a PrismaReadservice

import { Injectable } from '@nestjs/common';
import { Prisma, PrismaClient } from '@prisma/client';
import { logger } from '../logger/logger';

@Injectable()
export class PrismaReadService extends PrismaClient<
  Prisma.PrismaClientOptions,
  'query' | 'info' | 'warn' | 'error'
> {
  constructor() {
    let dbReadUrl = process.env.DATABASE_READ_URL;

    if (!dbReadUrl) {
        throw new Error('NO DATABASE URL DEFINED');
    }

    super({
      datasourceUrl: dbReadUrl
    });
  }
}

So i just use it as prismaService for write and PrismaReadService. It works but is not like this extension.

@Injectable()
export class AuthService {
  constructor(
    private readonly prisma: PrismaService,
    private readonly prismaRead: PrismaReadService,

Ofc will your responsibility in your code to not using read service for writing something, the code will not complain.

It worked well for me, thank you!

[cody-ax]

Here is a working example:

https://github.com/prisma/prisma/issues/18628#issuecomment-1611889400

[dminglv]

Implemented an example for NestJS: https://github.com/dminglv/nestjs-prisma-postgres-cluster

[MVitelli]

Here is a working example:

prisma/prisma#18628 (comment)

I have tried most of the solutions commented in that issue, but when trying to create a custom Prisma service with the readReplicas extension, I get a "maximum stack call exceeded" error that points to the extension code. I don't get the same error with other extensions.

@Injectable()
export class DatabaseService extends PrismaClient implements OnModuleInit, OnModuleDestroy {
  readonly extendedClient = prismaExtendedClient(this)

  constructor() {
    super()

    new Proxy(this, {
      get: (target, property) => Reflect.get(property in this.extendedClient ? this.extendedClient : target, property),
    })
  }

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

  async onModuleDestroy() {
    await this.$disconnect()
  }
}