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How to use Prisma in Bun

10 min

Introduction​

Bun is a fast JavaScript runtime that includes a bundler, test runner, and package manager. In this guide, you will set up a Bun project with Prisma ORM and a Prisma Postgres database. You will create a simple HTTP server and build a Bun executable for deployment.

Prerequisites​

1. Setting up your Bun project​

First, create a directory for your project and navigate to it:

mkdir bun-prisma
cd bun-prisma

Then, initialise a new Bun project:

bun init -y

This creates a basic Bun project that includes a package.json file and an index.ts file.

2. Installing and configuring Prisma​

2.1. Install dependencies​

Install the required Prisma packages and other dependencies:

bun add -d prisma
bun add @prisma/client

2.2. Initialize Prisma ORM with Prisma Postgres​

Initialize Prisma ORM with Prisma Postgres in your project:

bun prisma init --db
info

You'll need to answer a few questions while setting up your Prisma Postgres database. Select the region closest to your location and a memorable name for your database like "My Bun Project"

This command creates:

  • A prisma/ directory with your schema.prisma file
  • A new Prisma Postgres database
  • A prisma.config.ts file
  • A .env file with your DATABASE_URL

2.3. Configure environment variables for direct connection​

We're going to use a direct connection string for connecting to Prisma Postgres. To get your direct connection string:

  1. Navigate to your recently created Prisma Postgres project dashboard (e.g. "My Bun Project")
  2. Click the API Keys tab in the project's sidebar
  3. Click the Create API key button
  4. Provide a name for the API key and click Create
  5. Copy the connection string starting with postgres://

Update your .env file to replace the DATABASE_URL with the new connection string:

.env
DATABASE_URL="your_database_url_here"
DATABASE_URL="your_direct_connection_string_here"

2.4. Update your Prisma schema​

Open prisma/schema.prisma and update it to include your data model:

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

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

model User {
  id    Int     @id @default(autoincrement())
  email String  @unique
  name  String?
}

3. Setting up database configuration and creating a seed script​

3.1. Create a database utility file​

Create a db.ts file in your project root to configure PrismaClient:

db.ts
import { PrismaClient } from "./generated/prisma/client";

export const prisma = new PrismaClient();

3.2. Create a seed script​

Create a seed script in the prisma folder to populate your database with sample data:

prisma/seed.ts
import { PrismaClient } from "../generated/prisma/client";

const prisma = new PrismaClient();

async function main() {
  // Create multiple users
  await prisma.user.createMany({
    data: [
      { email: "alice@example.com", name: "Alice" },
      { email: "bob@example.com", name: "Bob" },
      { email: "charlie@example.com", name: "Charlie" },
      { email: "diana@example.com", name: "Diana" },
      { email: "eve@example.com", name: "Eve" },
      { email: "frank@example.com", name: "Frank" },
      { email: "grace@example.com", name: "Grace" },
      { email: "henry@example.com", name: "Henry" },
      { email: "isabella@example.com", name: "Isabella" },
      { email: "jack@example.com", name: "Jack" },
    ],
    skipDuplicates: true, // prevents errors if you run the seed multiple times
  });

  console.log("Seed data inserted!");
}

main()
  .catch((e) => {
    console.error(e);
    process.exit(1);
  })
  .finally(async () => {
    await prisma.$disconnect();
  });

3.3. Add the seed script to Prisma Config​

Add the following content to the file:

prisma.config.ts
import { defineConfig, env } from 'prisma/config';
export default defineConfig({
  schema: 'prisma/schema.prisma',
  migrations: { 
    path: 'prisma/migrations', 
    seed: `bun run prisma/seed.ts` 
  },
  engine: 'classic',
  datasource: {
    url: env('DATABASE_URL'),
  },
});

4. Generate Prisma client and run migrations​

Generate the Prisma client and apply your schema to the database:

bunx --bun prisma migrate dev --name init

This command:

  • Creates the database tables based on your schema
  • Generates the Prisma client in the generated/prisma directory

Run the seed script to populate your database:

bunx --bun prisma db seed

5. Creating your Bun server​

Replace the index.ts file contents with the following code to build a simple HTTP server that uses Prisma ORM to fetch and display users:

index.ts
import { prisma } from './db'

const server = Bun.serve({
  port: 3000,
  async fetch(req) {
    const { pathname } = new URL(req.url)

    // Skip favicon route
    if (pathname === '/favicon.ico') {
      return new Response(null, { status: 204 }) // or serve an icon if you have one
    }

    // Return all users
    const users = await prisma.user.findMany()

    // Count all users
    const count = await prisma.user.count()

    // Format the response with JSON
    return new Response(
      JSON.stringify({
        users: users,
        totalUsers: count,
      }),
      { headers: { 'Content-Type': 'application/json' } },
    )
  },
})

console.log(`Listening on http://localhost:${server.port}`)

6. Running your application​

Start your Bun server:

bun run index.ts

You should see Listening on http://localhost:3000 in the console. When you visit http://localhost:3000 in your browser, you'll see a JSON response with all the users in your database and the total count.

7. Building and running a Bun executable​

Bun can compile your TypeScript application into a single executable file, which is useful for deployment and distribution.

7.1. Build the executable​

Build your application into an executable:

bun build --compile index.ts

This creates an executable file named index (or index.exe on Windows) in your project directory.

7.2. Run the executable​

Run the compiled executable:

./index

You should see the same Listening on http://localhost:3000 message, and your application will work exactly the same as before. The executable includes all dependencies and can be deployed to any compatible system without requiring Bun or Node.js to be installed.

note

Bun executables are useful for:

  • Deployment: Ship a single file instead of managing dependencies
  • Distribution: Share your application without requiring users to install Bun
  • Performance: Faster startup times compared to running TypeScript files
  • Security: Your source code is compiled and not easily readable

Next steps​

You can explore the sample app here to see what you will build by following this guide. If you would like to add caching to your application, check out this example.

Now that you have a Bun application connected to a Prisma Postgres database, you can continue by:

  • Extending your Prisma schema with additional models and relationships
  • Implementing authentication and authorization
  • Adding input validation and error handling
  • Exploring Bun's built-in testing tools
  • Deploying your executable to production servers

More info​


Stay connected with Prisma

Continue your Prisma journey by connecting with our active community. Stay informed, get involved, and collaborate with other developers:

We genuinely value your involvement and look forward to having you as part of our community!

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