Querying with Prisma

INFO

This tutorial expects some familiarity with Prisma. Please refer to the Prisma docs if you need assistance on how to use it.

monolayer-pg can be integrated with Prisma.

You can combine monolayer-pg(schema definition in TypeScript and migration capabilities) with the Prisma(easy to use ORM).

Installing Prisma

From the root of your project, install Prisma, the Prisma client, and initialize Prisma with:

npm install prisma --save-dev
npm install @prisma/client
npx prisma init

Adapt configurations

In your .env file change the value of DATABASE_URL (inserted by Prisma) to value of MONO_PG_DEFAULT_DATABASE_URL.

WARNING

Don't delete the MONO_PG_DEFAULT_DATABASE_URL variable.

Then, adjust the database definition in databases.ts to generate the Prisma schema:

export default defineDatabase({
  schemas: [dbSchema],
  extensions: [extension("moddatetime")],
  camelCase: false,
  seeder: dbSeed,
  generatePrismaSchema: true, 
});

Generate the Prisma client

monolayer-pg generates the Prisma client after applying migrations.

Since Prisma was not configured the first time we applied migrations, we need to run the command again:

npx monolayer migrations apply --phase all

You should get the following output:

┌  Migrate all pending migrations (expand, alter, data, contract)
│
●  No migrations to apply.
│
◇  Generate prisma ✓
│
└  Done

How does it work?

After applying migrations, monolayer-pg executes prisma db pull and prisma generate on your behalf.

Prisma will automatically generate relationships between your models based on the relations established in the database through foreign keys.

Querying the database

In the same folder where the db folder is located, create a new file named example-prisma.ts and add the following code to it:

import { PrismaClient } from "@prisma/client";

const prisma = new PrismaClient();

async function main() {
  await prisma.posts.deleteMany();
  await prisma.users.deleteMany();
  await prisma.users.create({
    data: {
      name: "John Smith",
      email: "js@example.com",
      posts: {
        create: { title: "Sample", content: "Hello World" },
      },
    },
  });
  const allUsers = await prisma.users.findMany({
    select: {
      name: true,
      email: true,
      posts: {
        select: {
          title: true,
          content: true,
          published: true,
        },
      },
    },
  });
  console.dir(allUsers, { depth: 3 });
}

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

In this script we'll:

• Delete all posts and users.
• Create a user with a post.
• Query for all users and their posts.
• Output the result.

To run the script, run following command from your project root (replace the path with the actual path to example-prisma.ts) :

npx tsx path/to/example-prisma.ts

The output you get shoud be similar to:

[
  {
    name: 'John Smith',
    email: 'js@example.com',
    posts: [ { title: 'Sample', content: 'Hello World', published: false } ]
  }
]