How do you use Prisma with multiple databases in a single NestJS application?

Q: How do you use Prisma with multiple databases in a single NestJS application?

// Separate PrismaService per database @Injectable() export class UsersPrismaService extends PrismaClient implements OnModuleInit { constructor(config: ConfigService) { super({ datasources: { db: { url: config.get('USERS_DB_URL') } } }); } async onModuleInit() { await this.$connect(); } } @Injectable() export class AnalyticsPrismaService extends PrismaClient implements OnModuleInit { constructor(config: ConfigService) { super({ datasources: { db: { url: config.get('ANALYTICS_DB_URL') } } }); } async onModuleInit() { await this.$connect(); } } // Module — register both services @Module({ providers: [UsersPrismaService, AnalyticsPrismaService, ReportingService], exports: [UsersPrismaService, AnalyticsPrismaService], }) export class DatabaseModule {} // Service — inject the right client per database @Injectable() export class ReportingService { constructor( private usersPrisma: UsersPrismaService, private analyticsPrisma: AnalyticsPrismaService, ) {} async getDashboard(userId: number) { const [user, events] = await Promise.all([ this.usersPrisma.user.findUnique({ where: { id: userId } }), this.analyticsPrisma.event.findMany({ where: { userId } }), ]); return { user, events }; } } Create a separate PrismaService subclass per database — each manages its own connection pool. Pass the datasource URL via the constructor to avoid relying on environment variable naming conventions. Generate separate Prisma Clients if the schemas differ: npx prisma generate --schema prisma/schema-users.prisma. Cross-database transactions are not supported — design operations that only touch one database at a time. Use Promise.all() for parallel reads across databases when the operations are independent.

Difficulty: 5/10

Prisma client configuration, NestJS module design, Multi-database connection handling

Create a separate Prisma schema file and a separate PrismaService subclass for each database. Each service extends PrismaClient with its own datasource URL. Register them as separate providers in the module and inject the appropriate one into each service.

Multiple PrismaService instances for separate databases

Multi-database Prisma setup notes:

1
Create a separate PrismaService subclass per database — each manages its own connection pool.

How do you use Prisma with multiple databases in a single NestJS application?

Difficulty: 5/10

Prisma client configuration, NestJS module design, Multi-database connection handling

Create a separate Prisma schema file and a separate PrismaService subclass for each database. Each service extends PrismaClient with its own datasource URL. Register them as separate providers in the module and inject the appropriate one into each service.

Multiple PrismaService instances for separate databases

Multi-database Prisma setup notes:

1
Create a separate PrismaService subclass per database — each manages its own connection pool.

How do you use Prisma with multiple databases in a single NestJS application?

Create a separate Prisma schema file and a separate PrismaService subclass for each database. Each service extends PrismaClient with its own datasource URL. Register them as separate providers in the module and inject the appropriate one into each service.

How do you use Prisma with multiple databases in a single NestJS application?

Create a separate Prisma schema file and a separate PrismaService subclass for each database. Each service extends PrismaClient with its own datasource URL. Register them as separate providers in the module and inject the appropriate one into each service.

Scenario Questions

Follow-up Questions