Prisma With Fastify

Prisma gives you a fully typed query client generated from a schema. Wrap one PrismaClient in a Fastify plugin and disconnect on shutdown.

4 min read Level 2/5 #fastify#prisma#orm

What you'll learn

Install prisma and @prisma/client
Build a Prisma plugin that decorates the app
Use generated methods like db.user.findMany in handlers

Prisma is a code-generated ORM: you define models in schema.prisma, run prisma generate, and get a fully typed client. Wrapping it in a Fastify plugin takes about ten lines.

Install & Generate

npm install prisma @prisma/client
npx prisma init
# edit prisma/schema.prisma, then
npx prisma migrate dev --name init
npx prisma generate

The Plugin

import fp from 'fastify-plugin'
import { PrismaClient } from '@prisma/client'

declare module 'fastify' {
  interface FastifyInstance {
    db: PrismaClient
  }
}

export default fp(async (app) => {
  const prisma = new PrismaClient({ log: ['warn', 'error'] })
  await prisma.$connect()
  app.decorate('db', prisma)
  app.addHook('onClose', async () => {
    await prisma.$disconnect()
  })
})

Only one PrismaClient per process — instantiating multiple opens redundant pools.

Using the Typed Client

app.get('/users', async () => {
  return app.db.user.findMany({
    where: { active: true },
    select: { id: true, email: true },
  })
})

app.post('/users', async (req) => {
  const body = req.body as { email: string }
  return app.db.user.create({ data: { email: body.email } })
})

The return types are inferred from your schema — rename a column, and the compiler tells you every call that needs updating.

Drizzle With Fastify →