Support Prisma Client Extensions (Preview)

[marcjulian]

Prisma release with in version 4.7.0 Prisma Client Extensions (Preview)

This should be possible with the new CustomPrismaModule/CustomPrismaService (#40) where you can need to provide a PrismaClient instance.

[marcjulian]

Example to use Prisma Client Extensions.

1. Install Prisma Client v4.7.0 or later and install nestjs-prisma@v0.20.0-dev.2

2. Enable clientExtensions preview

datasource db {
  provider = "sqlite"
  url      = "file:dev.db"
}

generator client {
  provider        = "prisma-client-js"
  previewFeatures = ["clientExtensions"]
}

model User {
  id    String  @id @default(cuid())
  email String  @unique
  name  String?
}

3. Create a file for the Prisma extension prisma.extension.ts

import { PrismaClient } from '@prisma/client';

/**
 * TS error: "Inferred type of this node exceeds the maximum length the compiler will serialize" with "declaration": true in tsconfig
 *
 * Change "declaration": false in `tsconfig.json`
 *
 * https://github.com/prisma/prisma/issues/16536#issuecomment-1332055501
 */
export const prismaClient = new PrismaClient().$extends({
  model: {
    user: {
      findByEmail: async (email: string) => {
        return prismaClient.user.findFirstOrThrow({ where: { email } });
      },
    },
  },
});

export type prismaClient = typeof prismaClient;

4. Change declaration to false in your tsconfig.json - workaround for $extends TS error: "Inferred type of this node exceeds the maximum length the compiler will serialize" with "declaration": true in tsconfig prisma/prisma#16536 (comment)

The inferred type of this node exceeds the maximum length the compiler will serialize. An explicit type annotation is needed.

5. Use CustomPrismaModule.forRootAsync

import { Module } from '@nestjs/common';
import { CustomPrismaModule } from 'nestjs-prisma';
import { AppController } from './app.controller';
import { AppService } from './app.service';
import { prismaClient } from './prisma.extension';

@Module({
  imports: [
    CustomPrismaModule.forRootAsync({
      name: 'PrismaService',
      useFactory: () => {
        return prismaClient;
      },
    }),
  ],
  controllers: [AppController],
  providers: [AppService],
})
export class AppModule {}

6. Inject CustomPrismaService into your controller/service

import { Inject, Injectable } from '@nestjs/common';
import { CustomPrismaService } from 'nestjs-prisma';
import { prismaClient } from './prisma.extension';

@Injectable()
export class AppService {
  constructor(
    // ✅ use `prismaClient` from extension for correct type-safety
    @Inject('PrismaService')
    private prismaService: CustomPrismaService<prismaClient>,
  ) {}

  users() {
    return this.prismaService.client.user.findMany();
  }

  user(userId: string) {
    // 🦾 use new `findByEmail`
    return this.prismaService.client.user.findByEmail(userId);
  }
}

[shoaibsharif]

Thank you for the example. That helps a lot to understand how to use extension with new dev release version, but is there a way we can use extension in existing PrismaService or anyway to override that?

[marcjulian]

hi @shoaibsharif haven't found a way to use extension with the existing PrismaService as the service is directly extended by the default PrismaClient. For now you need to use CustomPrismaService.