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Prisma Setup

Installation​

npm install prisma @prisma/client
npx prisma init

This creates:

  • prisma/schema.prisma — your database schema
  • .env — with DATABASE_URL placeholder

Configure the Connection​

.env
DATABASE_URL="postgresql://postgres:password@localhost:5432/myapp"

schema.prisma​

prisma/schema.prisma
generator client {
  provider = "prisma-client-js"
}

datasource db {
  provider = "postgresql"
  url      = env("DATABASE_URL")
}

model User {
  id        String   @id @default(cuid())
  name      String
  email     String   @unique
  password  String
  role      Role     @default(USER)
  createdAt DateTime @default(now())
  updatedAt DateTime @updatedAt

  posts     Post[]
  profile   Profile?

  @@map("users")
}

enum Role {
  ADMIN
  USER
  GUEST
}

model Profile {
  id     String  @id @default(cuid())
  bio    String?
  avatar String?
  userId String  @unique

  user   User @relation(fields: [userId], references: [id], onDelete: Cascade)

  @@map("profiles")
}

model Post {
  id        String   @id @default(cuid())
  title     String
  content   String
  published Boolean  @default(false)
  authorId  String
  createdAt DateTime @default(now())
  updatedAt DateTime @updatedAt

  author    User    @relation(fields: [authorId], references: [id], onDelete: Cascade)
  tags      Tag[]   @relation("PostToTag")

  @@map("posts")
}

model Tag {
  id    String @id @default(cuid())
  name  String @unique
  posts Post[] @relation("PostToTag")

  @@map("tags")
}

Migrations​

# Create and apply migration (development)
npx prisma migrate dev --name init

# Apply migrations without creating new ones (CI/production)
npx prisma migrate deploy

# Reset database (DELETES ALL DATA — dev only)
npx prisma migrate reset

# Check status
npx prisma migrate status

Generate Client​

The client is auto-generated from your schema. Regenerate after any schema change:

npx prisma generate

Prisma Studio​

Visual database browser:

npx prisma studio
# Opens at http://localhost:5555

Prisma Client Setup​

src/lib/prisma.ts
import { PrismaClient } from '@prisma/client';
import { env } from '../env.js';

// Singleton pattern — avoids multiple connections in development
const globalForPrisma = globalThis as unknown as { prisma: PrismaClient };

export const prisma = globalForPrisma.prisma ?? new PrismaClient({
  log: env.isDev ? ['query', 'error', 'warn'] : ['error'],
});

if (env.isDev) globalForPrisma.prisma = prisma;
// Usage in any file
import { prisma } from '../lib/prisma.js';

const users = await prisma.user.findMany();