85 lines
2.5 KiB
Markdown
85 lines
2.5 KiB
Markdown
---
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title: "Prisma Client singleton"
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status: active
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audience: [ai-agent, contributor]
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language: nl
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last_updated: 2026-05-03
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when_to_read: "When importing or initialising the Prisma client in server code."
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---
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# Patroon: Prisma Client singleton
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## lib/prisma.ts
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PostgreSQL via `pg` + `@prisma/adapter-pg` (Neon/Vercel).
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```ts
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import { PrismaClient } from '@prisma/client'
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import { Pool } from 'pg'
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import { PrismaPg } from '@prisma/adapter-pg'
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function createPrismaClient() {
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const url = process.env.DATABASE_URL
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if (!url) throw new Error('DATABASE_URL is not set')
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const pool = new Pool({ connectionString: url })
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const adapter = new PrismaPg(pool)
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return new PrismaClient({
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adapter,
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log: process.env.NODE_ENV === 'development' ? ['error', 'warn'] : ['error'],
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})
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}
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const globalForPrisma = globalThis as unknown as { prisma: PrismaClient | undefined }
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export const prisma = globalForPrisma.prisma ?? createPrismaClient()
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if (process.env.NODE_ENV !== 'production') globalForPrisma.prisma = prisma
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```
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## prisma.config.ts (Prisma v7 vereiste)
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```ts
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import 'dotenv/config'
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import { defineConfig } from 'prisma/config'
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export default defineConfig({
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schema: 'prisma/schema.prisma',
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migrations: { path: 'prisma/migrations' },
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})
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```
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## Prisma generators
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`prisma/schema.prisma` bevat twee generators:
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```prisma
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generator client {
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provider = "prisma-client-js"
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}
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generator erd {
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provider = "prisma-erd-generator"
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output = "../docs/assets/erd.svg"
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}
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```
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`prisma generate` bouwt dus twee artifacts:
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- Prisma Client in `node_modules/@prisma/client`
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- het ERD-diagram in `docs/assets/erd.svg`
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Gebruik volledige `prisma generate` alleen lokaal. De ERD-generator gebruikt Mermaid/Puppeteer en mag niet in CI of Vercel draaien.
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## Commands
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| Command | Gebruik |
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|---|---|
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| `npx prisma db push` | Schema synchroniseren naar de database |
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| `npx prisma db seed` | Seeddata laden |
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| `npx prisma generate --generator client` | Alleen Prisma Client genereren; gebruiken in CI/deployment |
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| `npm run db:erd` | `prisma generate`: Prisma Client en `docs/assets/erd.svg` genereren |
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| `npm run db:erd:watch` | `prisma/schema.prisma` watchen en ERD opnieuw genereren |
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| `npm run dev` | Next.js dev server plus ERD watcher starten |
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Belangrijk: `db push` schrijft naar de database, maar genereert geen ERD. Gebruik na schemawijzigingen lokaal `npm run db:erd` of laat `npm run dev` de watcher draaien. Gebruik in CI en deployment alleen `npx prisma generate --generator client`.
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