Querying MongoDB with Prisma and Railway

All of this project's code can be found in the First Look monorepo on my GitHub.

Introduction

In this guide we will deploy a MongoDB database with Railway, add seed data to the database, connect to the database through a connection string, and create a Node script to query that seed data with Prisma Client.

Create Prisma Project

Create a blank new project and initialize a package.json.

bash
mkdir railway-prisma-mongodb
cd railway-prisma-mongodb
yarn init -y

Install the prisma dependencies.

bash
yarn add @prisma/client
yarn add -D prisma

Set type to module in package.json.

json
{
  "name": "railway-prisma-mongodb",
  "version": "1.0.0",
  "main": "index.js",
  "license": "MIT",
  "dependencies": {
    "@prisma/client": "^3.10.0"
  },
  "devDependencies": {
    "prisma": "^3.10.0"
  },
  "type": "module"
}

Initialize Prisma Schema

prisma init scaffolds a basic Prisma project.

bash
yarn prisma init

The only other necessary file is index.js. This is used for running test commands against our database with the Prisma Client.

bash
touch index.js

Our project now has the following structure:

text
/
├── prisma
│   └── schema.prisma
├── .env
├── .gitignore
├── index.js
└── package.json

Prisma Schema

Define a Post model by adding the following to the schema.prisma file.

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

generator client {
  provider        = "prisma-client-js"
  previewFeatures = ["mongoDb"]
}

model Post {
  id    String @id @default(auto()) @map("_id") @db.ObjectId
  slug  String @unique
  title String
  body  String
}

previewFeatures must be set to mongoDb in the client generator to enable MongoDB support.

Provision a MongoDB Database with Railway

There are two ways to setup a MongoDB database with Railway, through the dashboard or through the CLI.

Railway Dashboard

To use the dashboard, click dev.new and choose "Provision MongoDB."

01 - railway-project-dashboard

After the database is setup click "MongoDB" on the left to see the default test database that is autogenerated.

02 - mongodb-data-dashboard

Choose "Connect" to find your connection string.

03 - mongodb-connection-string

Railway CLI

If you want to use the Railway CLI instead of the dashboard, first you need to install it. To verify that you successfully installed the CLI, run the following command to check the CLI version.

bash
railway version

Run railway login to authenticate your Railway account. If you do not have a Railway account you will be prompted to create one.

bash
railway login

railway init initializes a project and asks if you want to start with an empty project or a starter template. Select “Empty Project” and give your project a name.

bash
railway init

Run railway add and select MongoDB to add the MongoDB plugin to your Railway project.

bash
railway add

Connect Railway Database to Prisma Project

Return to the Railway dashboard to find your connection string.

Set Environment Variable

Inside your .env file include DATABASE_URL and set the variable to the connection string provided by Railway. Specify the database name and authentication source at the end of the connection string by adding /test?authSource=admin after the port number.

text
DATABASE_URL="mongodb://mongo:<PASSWORD>@containers-us-west-1.railway.app:6852/test?authSource=admin"

Sync the schema with the database by using prisma db push.

bash
yarn prisma db push

Seed Database

You can also connect to the database directly with the mongosh command.

bash
mongosh "mongodb://mongo:<PASSWORD>@containers-us-west-1.railway.app:6852"

The database can be seeded from the Railway dashboard or through mongosh with the following seed command.

bash
db.Post.insertOne(
  {
    slug: "first-post-slug",
    title: "First Post Title",
    body: "First post body."
  }
)

Check the data tab in the Railway dashboard to see the data.

Generate Prisma Client

Generate the Prisma Client with the prisma generate command.

bash
yarn prisma generate

Create a Script to Query the Database

Add the following script to index.js to test that we can read data from our database. This function runs the findMany query on our post collection and returns all posts in the collection.

ts
// index.js

import pkg from '@prisma/client'

const { PrismaClient } = pkg
const prisma = new PrismaClient()

async function main() {
  await prisma.$connect()

  const posts = await prisma.post.findMany()

  console.dir(posts, { depth: Infinity })
}

main()
  .catch(console.error)
  .finally(() => prisma.$disconnect())

Run the Script

Run node index.js to execute the main function.

bash
node index.js

If you followed along correctly you should get the following output:

js
[
  {
    id: '61f369df79160504b0ee41d9',
    slug: 'first-post-slug',
    title: 'First Post Title',
    body: 'First post body.'
  }
]