Next.js 15 Full-Stack Application Development

What is Prisma?

Prisma is a modern, type-safe ORM (Object-Relational Mapper) for TypeScript. It provides type-safe queries, automatic migrations, and an intuitive API.

Installation

npm install prisma @prisma/client
npx prisma init --datasource-provider postgresql

Schema Definition

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

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

model User {
  id        Int       @id @default(autoincrement())
  email     String    @unique
  name      String
  role      Role      @default(USER)
  posts     Post[]
  createdAt DateTime  @default(now())

  @@map("users")
}

model Post {
  id         Int       @id @default(autoincrement())
  title      String
  content    String
  published  Boolean   @default(false)
  author     User      @relation(fields: [authorId], references: [id])
  authorId   Int
  tags       Tag[]
  createdAt  DateTime  @default(now())
  updatedAt  DateTime  @updatedAt

  @@map("posts")
}

model Tag {
  id    Int    @id @default(autoincrement())
  name  String @unique
  posts Post[]

  @@map("tags")
}

enum Role {
  ADMIN
  USER
}

Running Migrations

npx prisma migrate dev --name init
npx prisma studio  # Visual database editor

Prisma Client Singleton

// lib/prisma.ts
import { PrismaClient } from "@prisma/client";

const globalForPrisma = globalThis as unknown as {
  prisma: PrismaClient | undefined;
};

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

if (process.env.NODE_ENV !== "production") {
  globalForPrisma.prisma = prisma;
}

CRUD Operations

import { prisma } from "@/lib/prisma";

// CREATE
const newUser = await prisma.user.create({
  data: { email: "[email protected]", name: "John Doe" },
});

// READ (single)
const user = await prisma.user.findUnique({
  where: { id: 1 },
  include: { posts: true },
});

// READ (list with pagination)
const posts = await prisma.post.findMany({
  where: { published: true },
  orderBy: { createdAt: "desc" },
  take: 10,
  skip: (page - 1) * 10,
  include: { author: { select: { name: true } } },
});

// UPDATE
const updated = await prisma.user.update({
  where: { id: 1 },
  data: { name: "Updated Name" },
});

// DELETE
await prisma.user.delete({ where: { id: 1 } });

// COUNT
const total = await prisma.post.count({ where: { published: true } });