Use Prisma with Bun

Create a directory and initialize it with bun init.

mkdir prisma-app
cd prisma-app
bun init

Run orm init with bunx, which installs prisma and @prisma/orm-postgres with bun add and writes a starter schema to src/prisma/contract.prisma, a database client to src/prisma/db.ts, a prisma.config.ts and a .env file. The --authoring psl flag picks the Prisma Schema Language, the .prisma format from earlier Prisma versions.

bunx prisma@latest orm init --yes --target postgres --authoring psl --write-env

The starter schema defines a User model and a Post model:

src/prisma/contract.prisma

// use prisma-8

model User {
  id        Int      @id @default(autoincrement())
  email     String   @unique
  username  String?
  name      String?
  posts     Post[]
  createdAt TimestamptzString @default(now())
  updatedAt temporal.updatedAtString()
}

model Post {
  id        Int      @id @default(autoincrement())
  title     String
  content   String?
  author    User     @relation(fields: [authorId], references: [id])
  authorId  Int
  createdAt TimestamptzString @default(now())
  updatedAt temporal.updatedAtString()
}

Prisma ORM compiles this file into a contract, src/prisma/contract.json and src/prisma/contract.d.ts, that your queries are type-checked against. orm init emits it once, and after every later change to the schema you run bunx prisma contract emit to update it.

Every prisma command ends with a line that says the agent skills are out of date, which changes nothing and goes away once you run bunx prisma@latest init to install the skills for your coding agent.

Set DATABASE_URL in the .env file to the connection string of an empty PostgreSQL 15 or newer database, because the next step creates tables in it. If you do not have one, bunx create-db creates a Prisma Postgres database without an account and prints its connection string together with a claim URL, and because the database and its data are deleted after 24 hours unless you open that URL, claim it if you want to keep it. The string from create-db ends in sslmode=require, which makes the pg driver print a security warning on every connection, so change it to sslmode=verify-full, the mode Prisma Postgres supports. Leave the SSL settings of another provider as its documentation gives them.

DATABASE_URL="postgres://USER:PASSWORD@db.prisma.io:5432/postgres?sslmode=verify-full"

prisma.config.ts and src/prisma/db.ts load .env through dotenv, so the CLI and your code both read the variable from there.

db init creates the tables from the contract and records the contract in the database.

bunx prisma db init

✔ Applied 5 operation(s) across 1 contract space

App space
├─ Create table "Post"
├─ Create table "User"
├─ Add unique constraint on "User" (email)
├─ Create index "Post_authorId_idx_e47547ed" on "Post"
├─ Add foreign key "Post_authorId_fkey" on "Post"
└─ marker a51b4833fdaffe730572670ccc27dd89af7e0726ab3de7f428d21702d687cc15

Replace index.ts with a script that creates a new user, then counts the users in the database. Models are namespace-qualified on PostgreSQL, so the User model in the default public schema is db.orm.public.User.

import { db } from "./src/prisma/db";

// create a new user
await db.orm.public.User.create({
  name: "John Dough",
  email: `john-${Math.random()}@example.com`,
});

// count the users
const { count } = await db.orm.public.User.aggregate(a => ({ count: a.count() }));
console.log(`There are ${count} users in the database.`);

await db.close();

The final db.close() lets the script exit, because otherwise the connection pool keeps the process alive.

Run the script with bun and watch the count grow, because each run creates a new user.

bun index.ts

There are 1 users in the database.

bun index.ts

There are 2 users in the database.

bun index.ts

There are 3 users in the database.