Prisma as ORM

So let's set up a simple app with Prisma and JavaScript.

By the way, Prisma can also be used in python with Flask. However, this week we will use Express and JavaScript.

Setting Up Prisma with Express.js

1. Installation:

Create the folder app and navigate into it:

mkdir prisma-test
cd prisma-test

Start by initializing a new Node.js project if you haven't already:

npm init -y

Install all required dependences:

npm install prisma @prisma/client express

Now, set up Prisma for your project:

npx prisma init --datasource-provider sqlite --url file:./dev.db

This command generates a prisma directory with 3 files:

schema.prisma. You define all your tables information (also known as models).
dev.db. Contains the database itself. Never touch this file.
As well, in the root folder you will have a .env file (for environment variables like the DB url).

2. Defining Models:

Inside schema.prisma, you can define your data models. It's like tables in the SQL universe.

Here's a basic example with a User table (model):

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

The above definition creates a User with an id, name, and email fields, with email being unique.

Copy this code in your schema.prisma file.

3. Integration with Express.js:

In your root folder create a file index.js.

touch index.js

Now, in your main server file (e.g., index.js), set up a basic Express.js application connected to Prisma.

const express = require('express');
const { PrismaClient } = require('@prisma/client');

const prisma = new PrismaClient();
const app = express();

app.use(express.json());

// Sample route to fetch all users
app.get('/users', async (req, res) => {
    const users = await prisma.user.findMany();
    res.json(users);
});

const PORT = 8000;
app.listen(PORT, () => {
    console.log(`Server is running on http://localhost:${PORT}`);
});

This sets up a basic Express server with a single route to fetch all users from the database.

4. Seeding the Database:

To seed the database (add some test users into DB) with Prisma, we'll add a seeding script.

Create a new file called seed.js in the prisma folder of your project (prisma/seed.js). In this file, you'll add the logic to insert sample users into the database:

const { PrismaClient } = require('@prisma/client');

const prisma = new PrismaClient();

async function main() {
    await prisma.user.create({
        data: {
            name: 'John Doe',
            email: 'john.doe@example.com',
        },
    });

    await prisma.user.create({
        data: {
            name: 'Jane Smith',
            email: 'jane.smith@example.com',
        },
    });

    // You can add more users or other data as needed
}

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

Next, add the prisma.seed to your package.json file (you should add this just before the last curly bracket in your package.json file):

,
  "prisma": {
    "seed": "node prisma/seed.js"
  }

5. Migrating the Database:

So far you only created the "mould of your information". But the database is empty, you need to create the tables and run the seed file to populate this tables. This process is called migration:

In your terminal run:

npx prisma migrate dev --name init

Finally, to seed the database, run the CLI command: npx prisma db seed

6. Run your app

Finally run:

node index.js

This command will run the Express server in port 8000 (http://localhost:8000) and navigate to the http://localhost:8000/users endpoint, you'll see the seeded users in the response.

Web Application Development