MongoDB

MongoDB is a popular document-based NoSQL database known for its flexibility, scalability, and developer-friendly features. In this guide, you will learn how to add Prisma ORM to an existing TypeScript project, connect it to MongoDB, introspect your existing database schema, and start querying with type-safe Prisma Client.

Prerequisites

In order to successfully complete this guide, you need:

• Node.js installed on your machine (see system requirements for officially supported versions)
• An existing TypeScript project with a package.json file
• Access to a MongoDB 4.2+ server with a replica set deployment. We recommend using MongoDB Atlas.

Make sure you have your database connection URL (that includes your authentication credentials) at hand!

1. Set up Prisma ORM

Navigate to your existing project directory and install the required dependencies:

npm install prisma@6.19 @types/node --save-dev
npm install @prisma/client@6.19 dotenv

Here's what each package does:

• prisma - The Prisma CLI for running commands like prisma init, prisma db pull, and prisma generate
• @prisma/client - The Prisma Client library for querying your database
• dotenv - Loads environment variables from your .env file

2. Initialize Prisma ORM

Set up your Prisma ORM project by creating your Prisma Schema file with the following command:

npx prisma init --datasource-provider mongodb --output ../generated/prisma

This command does a few things:

• Creates a prisma/ directory with a schema.prisma file containing your database connection configuration
• Creates a .env file in the root directory for environment variables
• Creates a prisma.config.ts file for Prisma configuration

The generated prisma.config.ts file looks like this:

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

export default defineConfig({
  schema: "prisma/schema.prisma",
  migrations: {
    path: "prisma/migrations",
  },
  engine: "classic",
  datasource: {
    url: env("DATABASE_URL"),
  },
});

Add dotenv to prisma.config.ts so that Prisma can load environment variables from your .env file:

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

export default defineConfig({
  schema: "prisma/schema.prisma",
  migrations: {
    path: "prisma/migrations",
  },
  engine: "classic",
  datasource: {
    url: env("DATABASE_URL"),
  },
});

The generated schema uses the ESM-first prisma-client generator with a custom output path:

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

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

3. Connect your database

Update the .env file with your MongoDB connection URL:

DATABASE_URL="mongodb+srv://username:password@cluster.mongodb.net/mydb"

For MongoDB Atlas, the connection URL format is:

mongodb+srv://USERNAME:PASSWORD@CLUSTER.mongodb.net/DATABASE

Self-hosted MongoDB connection URL format:

mongodb://USERNAME:PASSWORD@HOST:PORT/DATABASE

Connection URL components:

• USERNAME: Your database user name
• PASSWORD: Your database user password
• HOST: The host where mongod or mongos is running
• PORT: The port where your database server is running (typically 27017)
• DATABASE: The name of your database

Troubleshooting connection issues

• Authentication failed — If you see a SCRAM failure: Authentication failed error, add ?authSource=admin to the end of your connection string.
• Empty database name — If you see an Error code 8000 (AtlasError): empty database name not allowed error, append the database name to your connection URL. See this GitHub issue for details.

4. Introspect your database

Run the following command to introspect your existing database:

npx prisma db pull

This command:

• Reads the DATABASE_URL from your .env file
• Connects to your MongoDB database
• Samples documents in your collections to infer the schema
• Generates Prisma models in your schema.prisma file

5. Generate Prisma ORM types

Generate Prisma Client based on your introspected schema:

npx prisma generate

This creates a type-safe Prisma Client tailored to your database schema in the generated/prisma directory.

6. Instantiate Prisma Client

Create a utility file to instantiate Prisma Client:

import "dotenv/config";
import { PrismaClient } from "../generated/prisma/client";

const prisma = new PrismaClient();

export { prisma };

7. Query your database

Now you can use Prisma Client to query your database. Create a script.ts file:

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

async function main() {
  // Example: Fetch all records from a collection
  // Replace 'user' with your actual model name
  const allUsers = await prisma.user.findMany();
  console.log("All users:", JSON.stringify(allUsers, null, 2));
}

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

Run the script:

npx tsx script.ts

8. Evolve your schema

MongoDB doesn't support migrations like relational databases. Instead, use db push to sync schema changes:

8.1. Update your Prisma schema file

Modify your Prisma schema file with the changes you want. For example, add a new model:

model Post { 
  id        String   @id @default(auto()) @map("_id") @db.ObjectId
  title     String
  content   String?
  published Boolean  @default(false) 
  authorId  String   @db.ObjectId
  author    User     @relation(fields: [authorId], references: [id]) 
} 

model User { 
  id    String @id @default(auto()) @map("_id") @db.ObjectId
  email String @unique
  name  String?
  posts Post[]
} 

8.2. Push the changes to your database

npx prisma db push

This command:

• Applies schema changes to your MongoDB database
• Automatically regenerates Prisma Client

9. Explore your data

You can use MongoDB Atlas, the MongoDB shell, or MongoDB Compass to view and manage your data.

Next steps

You've successfully set up Prisma ORM. Here's what you can explore next:

• Learn more about Prisma Client: Explore the Prisma Client API for advanced querying, filtering, and relations
• Database migrations: Learn about Prisma Migrate for evolving your database schema
• Performance optimization: Discover query optimization techniques
• Build a full application: Check out our framework guides to integrate Prisma ORM with Next.js, Express, and more
• Join the community: Connect with other developers on Discord

More info

• MongoDB database connector
• Prisma Config reference
• Database introspection