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

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

generator client {
  provider = "prisma-client-js"
  // Useful features for 2025+
  previewFeatures = ["driverAdapters", "metrics"]
}

// Standard Shopify Session Model
model Session {
  id          String    @id
  shop        String
  state       String
  isOnline    Boolean   @default(false)
  scope       String?
  expires     DateTime?
  accessToken String
  userId      BigInt?
}

// app/db.server.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;

model Product {
  id          BigInt   @id // Matches Shopify's ID
  shop        String
  title       String
  // ...
  @@index([shop]) // Always index by shop for multi-tenancy
}

// BAD: Fetches massive JSON blobs
const products = await prisma.product.findMany();

// GOOD
const products = await prisma.product.findMany({
  select: { id: true, title: true }
});

await prisma.$transaction(async (tx) => {
  const order = await tx.order.create({ ... });
  await tx.lineItem.create({ ... });
});

await prisma.user.upsert({
  where: { id: 1 },
  update: { email: "new@example.com" },
  create: { id: 1, email: "new@example.com" },
});