Bun

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

• Bun installed in your system
• A Prisma Postgres database (created during setup)
• Basic knowledge of JavaScript/TypeScript

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 @types/pg
bun add @prisma/client @prisma/adapter-pg pg

2.2. Initialize Prisma ORM with Prisma Postgres

Initialize Prisma ORM with Prisma Postgres in your project:

bunx --bun prisma init --db

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:

DATABASE_URL="your_database_url_here" // [!code --]
DATABASE_URL="your_direct_connection_string_here" // [!code ++]

2.4. Update your Prisma schema

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

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

datasource db {
  provider = "postgresql"
}

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

3. Generate Prisma Client and run migrations

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

bunx --bun prisma migrate dev --name init
bunx --bun prisma generate

This command:

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

4. Setting up database configuration and creating a seed script

4.1. Create a database utility file

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

import { PrismaClient } from "./generated/prisma/client";
import { PrismaPg } from "@prisma/adapter-pg";

const adapter = new PrismaPg({
  connectionString: process.env.DATABASE_URL!,
});

export const prisma = new PrismaClient({
  adapter,
});

4.2. Create a seed script

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

import { PrismaClient } from "../generated/prisma/client";
import { PrismaPg } from "@prisma/adapter-pg";

const adapter = new PrismaPg({
  connectionString: process.env.DATABASE_URL!,
});

const prisma = new PrismaClient({
  adapter,
});

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:

import { defineConfig, env } from "prisma/config";

export default defineConfig({
  schema: "prisma/schema.prisma",
  migrations: {
    path: "prisma/migrations",
    seed: `bun run prisma/seed.ts`, 
  },
  datasource: {
    url: env("DATABASE_URL"),
  },
});

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:

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.

Next steps

You can explore this example to see a sample application built with Bun and Prisma.

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

• Bun Documentation
• Prisma Config File
• Prisma Postgres