NestJS Prisma

PrismaService as a Nest Provider

Prisma is not wrapped by an official Nest module the way TypeORM is. The common pattern is a PrismaService that extends PrismaClient, connects on module init, and is exported from a global database module.

@Injectable()
export class PrismaService extends PrismaClient implements OnModuleInit, OnModuleDestroy {
  async onModuleInit() {
    await this.$connect();
  }

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

Lifecycle hooks ensure Prisma connects once when Nest starts and disconnects cleanly on shutdown.

Schema Model and Query Example

// schema.prisma
model User {
  id    Int    @id @default(autoincrement())
  email String @unique
}

// users.service.ts
const user = await this.prisma.user.create({
  data: { email: dto.email },
});

• Run npx prisma migrate dev to apply schema changes locally.
• Run npx prisma generate after schema edits so the TypeScript client updates.
• Inject PrismaService into feature services rather than constructing PrismaClient repeatedly.
• Use $transaction for multi-step writes that must succeed or fail together.

Prisma Nest Cheatsheet

Commands and APIs you will use constantly.

Global Prisma Module

Mark a PrismaModule as @Global() and export PrismaService so every feature module can inject it without re-importing. Keep direct Prisma access out of controllers.

@Global()
@Module({
  providers: [PrismaService],
  exports: [PrismaService],
})
export class PrismaModule {}

DTOs vs Generated Prisma Types

Do not expose Prisma input types directly as HTTP DTOs. Keep class-validator DTOs at the boundary and map to Prisma create/update inputs inside services.

Common Mistakes

• Creating a new PrismaClient instance in every service instead of a shared provider.
• Committing credentials in schema.prisma instead of using env("DATABASE_URL").
• Forgetting to regenerate the client after schema changes.
• Passing unvalidated request bodies straight into Prisma create calls.

Key Takeaways

• Wrap PrismaClient in a Nest PrismaService with connect/disconnect lifecycle hooks.
• Export PrismaService from a (often global) module for DI across features.
• Prisma schema + migrate + generate is the source of database types.
• Keep HTTP DTOs separate from Prisma generated input types.