Prisma

Prisma Database Operations

Database Package Location

The Prisma schema and client are in packages/db/.

Schema Location

packages/db/
├── prisma/
│   ├── schema.prisma    # Database schema
│   ├── migrations/      # Migration history
│   └── seed.ts          # Seed script
└── src/
    └── lib/
        ├── prisma.service.ts           # NestJS Prisma service
        └── [model]/                    # Repository services
            └── [model]-repository.service.ts

Common Commands

# Generate Prisma client after schema changes
pnpm prisma:generate

# Create and apply migration (development)
pnpm prisma:migrate:dev

# Apply migrations (production)
pnpm prisma:migrate

# Seed the database
pnpm prisma:seed

# Open Prisma Studio
pnpm --filter @projectx/db exec prisma studio

Schema Patterns

Basic Model

model Product {
  id          String   @id @default(cuid())
  name        String
  description String?
  price       Decimal  @db.Decimal(10, 2)
  createdAt   DateTime @default(now())
  updatedAt   DateTime @updatedAt

  // Relations
  categoryId  String
  category    Category @relation(fields: [categoryId], references: [id])
  orderItems  OrderItem[]

  @@index([categoryId])
  @@map("products")
}

PostGIS Geometry Support

model Location {
  id        String   @id @default(cuid())
  name      String
  // PostGIS geometry stored as Unsupported type
  point     Unsupported("geometry(Point, 4326)")

  @@map("locations")
}

Enums

enum OrderStatus {
  PENDING
  PROCESSING
  SHIPPED
  DELIVERED
  CANCELLED
}

Repository Pattern

Creating a Repository Service

// packages/db/src/lib/product/product-repository.service.ts
import { Injectable } from '@nestjs/common';
import { PrismaService } from '../prisma.service';
import { Prisma, Product } from '@prisma/client';

@Injectable()
export class ProductRepositoryService {
  constructor(private readonly prisma: PrismaService) {}

  async findAll(params?: {
    skip?: number;
    take?: number;
    cursor?: Prisma.ProductWhereUniqueInput;
    where?: Prisma.ProductWhereInput;
    orderBy?: Prisma.ProductOrderByWithRelationInput;
  }): Promise<Product[]> {
    return this.prisma.product.findMany(params);
  }

  async findById(id: string): Promise<Product | null> {
    return this.prisma.product.findUnique({
      where: { id },
      include: { category: true },
    });
  }

  async create(data: Prisma.ProductCreateInput): Promise<Product> {
    return this.prisma.product.create({ data });
  }

  async update(id: string, data: Prisma.ProductUpdateInput): Promise<Product> {
    return this.prisma.product.update({
      where: { id },
      data,
    });
  }

  async delete(id: string): Promise<Product> {
    return this.prisma.product.delete({ where: { id } });
  }
}

Query Patterns

Filtering and Pagination

const products = await prisma.product.findMany({
  where: {
    name: { contains: 'shirt', mode: 'insensitive' },
    price: { gte: 10, lte: 100 },
    category: { name: 'Clothing' },
  },
  skip: 0,
  take: 20,
  orderBy: { createdAt: 'desc' },
  include: { category: true },
});

Transactions

const [order, inventory] = await prisma.$transaction([
  prisma.order.create({ data: orderData }),
  prisma.inventory.update({
    where: { productId },
    data: { quantity: { decrement: quantity } },
  }),
]);

Raw SQL (for PostGIS)

const nearbyLocations = await prisma.$queryRaw`
  SELECT id, name, ST_AsGeoJSON(point) as geojson
  FROM locations
  WHERE ST_DWithin(
    point,
    ST_SetSRID(ST_MakePoint(${lng}, ${lat}), 4326)::geography,
    ${radiusMeters}
  )
`;

Migration Workflow

1. Modify schema.prisma with your changes
2. Generate migration: pnpm prisma:migrate:dev --name descriptive_name
3. Review migration in prisma/migrations/
4. Test locally before committing
5. Apply in production: pnpm prisma:migrate

Seeding

// packages/db/prisma/seed.ts
import { PrismaClient } from '@prisma/client';

const prisma = new PrismaClient();

async function main() {
  // Upsert to avoid duplicates
  await prisma.category.upsert({
    where: { slug: 'electronics' },
    update: {},
    create: {
      name: 'Electronics',
      slug: 'electronics',
    },
  });
}

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

Best Practices

1. Use repository services instead of direct Prisma calls in controllers
2. Always include @@map for explicit table names
3. Add indexes for frequently queried fields
4. Use transactions for related operations
5. Name migrations descriptively (e.g., add_product_inventory)
6. Validate data at the application layer before database operations

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