Prisma is a wonderful ORM and it is very easy to setup. You can use Prisma with any database. Prisma is a type-safe database client. It helps you to write queries in your language and it converts it to SQL queries.

Basic Project Setup

If you look at my previous article on Setting up Express, I'm using a specific folder structure. I'll be using the same folder structure here.

*
|--- src
|    |--- db
|    |    |--- schema.prisma
|    |--- app.ts

You can checkout my previous article Setting up Express to setup a project with javascript or typescript.

Prisma Setup

First, you need to install Prisma globally.

npm install prisma

Then, you need to initialize Prisma in your project.

npx prisma init

This will create a prisma folder in your project. Inside the prisma folder, you will find a schema.prisma file. This is where you define your database schema.

Database Connection

Overall you have two choices either you can use a SQL based database or a NoSQL based database. Here is the official doc I'll show you how to work with MongoDB and Postgres, which are the two popular choices.

In the prisma/schema.prisma file, you can define your database connection.

The file looks like this

generator client {
  provider = "prisma-client-js"
}
 
datasource db {
  provider = "postgresql"
  url      = env("DATABASE_URL")
}

The provider is the type of database you are using. In this case, it is "postgresql". You can change it to "mongodb" if you are using MongoDB.

The url comes from the environment variable. You can set the environment variable in a .env file.

DATABASE_URL="postgresql://user:password@localhost:5432/dbname"

Now define a model

You can define your model in the schema.prisma file. Here is an example of a user model.

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

Query database with Prisma Client

Prisma Client is a type-safe database client. It helps you to write queries in your language and it converts it to SQL queries.

Install the client

npm install @prisma/client

You will have to generate the client. You can do this by running the following command.

npx prisma generate

This will prepare the client for you. You can now use the client to query the database.

Now setup the client object as per the documentation. I like to do it inside db/prisma-client.ts

import { PrismaClient } from "@prisma/client";
 
const globalForPrisma = globalThis as unknown as { prisma: PrismaClient };
 
export const prisma = globalForPrisma.prisma || new PrismaClient();
 
if (process.env.NODE_ENV !== "production") globalForPrisma.prisma = prisma;
 

Now you can import the client and directly use it like this :

import { prisma } from "./db/prisma-client";
 
const main = async () => {
  const user = await prisma.user.count();
  console.log("User count: ", user);
};
 
main();

SQL vs NoSQL and Docker Images

There is a slight difference in the connection setup for SQL and NoSQL databases.

SQL or relational databases require a table structure and needs to be migrated before you can use it. You can use the following command to migrate the database.

npx prisma migrate dev

This will create the tables in the database or update the existing table. The step is not required for non relational databases like MongoDB.

MongoDB

If you don't have MongoDB installed, you can use the docker image. You can run the following command to start a MongoDB instance.

docker run -d -p 27017:27017 --name mongodb mongo

If you are using MongoDB, you can define the connection like this.

generator client {
  provider = "prisma-client-js"
}
 
datasource db {
  provider = "mongodb"
  url      = env("DATABASE_URL") || "mongodb://localhost:27017/test"
}

Postgres

If you don't have Postgres installed, you can use the docker image. You can run the following command to start a Postgres instance.

docker run -d -p 5432:5432 --name postgres -e POSTGRES_PASSWORD=password postgres

If you are using Postgres, you can define the connection like this.

generator client {
  provider = "prisma-client-js"
}
 
datasource db {
  provider = "postgresql"
  url      = env("DATABASE_URL") || "postgresql://postgres:password@localhost:5432/test"
}

Prisma is a wonderful ORM and it is very easy to setup. You can use Prisma with many databases, it makes querying databases easier and is widely used. Enjoy using Prisma!