Prisma Query Standards

This rule applies to files matching the patterns above.

# Prisma Query Standards

## Rule
All Prisma queries MUST use explicit select or include, handle errors, and avoid N+1 patterns. Bulk operations MUST use batch methods.

## Format
```typescript
const result = await prisma.model.findMany({
  where: { /* filter */ },
  select: { /* specific fields */ },
  orderBy: { createdAt: 'desc' },
  take: 20,
});
```

## Requirements

### Use select for Lists
```typescript
// GOOD: Only fetch needed fields
const posts = await prisma.post.findMany({
  select: {
    id: true,
    title: true,
    slug: true,
    author: { select: { name: true } },
  },
  take: 20,
});

// BAD: Fetching all fields
const posts = await prisma.post.findMany();
```

### Handle Errors
```typescript
// GOOD: Explicit error handling
try {
  const user = await prisma.user.findUniqueOrThrow({
    where: { id: userId },
  });
  return user;
} catch (error) {
  if (error instanceof Prisma.PrismaClientKnownRequestError) {
    if (error.code === 'P2025') throw new NotFoundError('User not found');
  }
  throw error;
}
```

### Use Transactions for Related Writes
```typescript
// GOOD: Atomic operation
const [post, notification] = await prisma.$transaction([
  prisma.post.create({ data: postData }),
  prisma.notification.create({ data: notificationData }),
]);

// BAD: Non-atomic (notification may fail after post is created)
const post = await prisma.post.create({ data: postData });
const notification = await prisma.notification.create({ data: notificationData });
```

### Batch Operations
```typescript
// GOOD: Single query for bulk insert
await prisma.tag.createMany({ data: tags, skipDuplicates: true });

// BAD: Loop with individual creates
for (const tag of tags) {
  await prisma.tag.create({ data: tag });
}
```

## Anti-Patterns
- Fetching all fields when only a few are needed
- Individual queries in loops (N+1)
- Not handling Prisma-specific errors
- Related writes without transactions
- Offset pagination on large tables

## Enforcement
Enable Prisma query logging in development.
Flag queries without select/include in code review.
Monitor slow queries in production with $on('query').