How to handle database errors and transactions in Prisma

Handling Known Errors

Prisma throws typed errors. Import the error class to handle specific cases:

import { PrismaClientKnownRequestError } from '@prisma/client/runtime/library'

export async function createUser(email: string) {
  try {
    return await prisma.user.create({ data: { email } })
  } catch (e) {
    if (e instanceof PrismaClientKnownRequestError) {
      if (e.code === 'P2002') {
        // Unique constraint violation
        return { error: 'Email already exists' }
      }
      if (e.code === 'P2025') {
        // Record not found (for update/delete)
        return { error: 'User not found' }
      }
    }
    throw e  // Re-throw unexpected errors
  }
}

Transactions

Use prisma.$transaction when multiple operations must succeed or fail together:

// Transfer credits between users
await prisma.$transaction(async (tx) => {
  const sender = await tx.user.update({
    where: { id: senderId },
    data: { credits: { decrement: amount } },
  })

  if (sender.credits < 0) {
    throw new Error('Insufficient credits')  // Triggers rollback
  }

  await tx.user.update({
    where: { id: receiverId },
    data: { credits: { increment: amount } },
  })
})

Interactive transactions receive a tx client — use it for all queries inside the callback. Throwing any error inside the callback automatically rolls back all changes. Never use the regular prisma client inside a transaction callback.