Custom validation

You can add runtime validation for your user input for Prisma Client queries in one of the following ways:

• Prisma Client extensions
• A custom function

You can use any validation library you'd like. The Node.js ecosystem offers a number of high-quality, easy-to-use validation libraries to choose from including: joi, validator.js, Yup, Zod and Superstruct.

Input validation with Prisma Client extensions

This example adds runtime validation when creating and updating values using a Zod schema to check that the data passed to Prisma Client is valid.

warning

Query extensions do not currently work for nested operations. In this example, validations are only run on the top level data object passed to methods such as prisma.product.create(). Validations implemented this way do not automatically run for nested writes.

Prisma Client extension

import { PrismaClient, Prisma } from '@prisma/client'
import { z } from 'zod'

/**
 * Zod schema
 */
export const ProductCreateInput = z.object({
  slug: z
    .string()
    .max(100)
    .regex(/^[a-z0-9]+(?:-[a-z0-9]+)*$/),
  name: z.string().max(100),
  description: z.string().max(1000),
  price: z
    .instanceof(Prisma.Decimal)
    .refine((price) => price.gte('0.01') && price.lt('1000000.00')),
}) satisfies z.Schema<Prisma.ProductUncheckedCreateInput>

/**
 * Prisma Client Extension
 */
const prisma = new PrismaClient().$extends({
  query: {
    product: {
      create({ args, query }) {
        args.data = ProductCreateInput.parse(args.data)
        return query(args)
      },
      update({ args, query }) {
        args.data = ProductCreateInput.partial().parse(args.data)
        return query(args)
      },
      updateMany({ args, query }) {
        args.data = ProductCreateInput.partial().parse(args.data)
        return query(args)
      },
      upsert({ args, query }) {
        args.create = ProductCreateInput.parse(args.create)
        args.update = ProductCreateInput.partial().parse(args.update)
        return query(args)
      },
    },
  },
})

async function main() {
  /**
   * Example usage
   */
  // Valid product
  const product = await prisma.product.create({
    data: {
      slug: 'example-product',
      name: 'Example Product',
      description: 'Lorem ipsum dolor sit amet',
      price: new Prisma.Decimal('10.95'),
    },
  })

  // Invalid product
  try {
    await prisma.product.create({
      data: {
        slug: 'invalid-product',
        name: 'Invalid Product',
        description: 'Lorem ipsum dolor sit amet',
        price: new Prisma.Decimal('-1.00'),
      },
    })
  } catch (err: any) {
    console.log(err?.cause?.issues)
  }
}

main()

Prisma schema

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

generator client {
  provider = "prisma-client-js"
}

model Product {
  id          String   @id @default(cuid())
  slug        String
  name        String
  description String
  price       Decimal
  reviews     Review[]
}

model Review {
  id        String  @id @default(cuid())
  body      String
  stars     Int
  product   Product @relation(fields: [productId], references: [id], onDelete: Cascade)
  productId String
}

The above example uses a Zod schema to validate and parse data provided in a query at runtime before a record is written to the database.

Input validation with a custom validation function

Here's an example using Superstruct to validate that the data needed to signup a new user is correct:

import { PrismaClient, Prisma, User } from '@prisma/client'
import { assert, object, string, size, refine } from 'superstruct'
import isEmail from 'isemail'

const prisma = new PrismaClient()

// Runtime validation
const Signup = object({
  // string and a valid email address
  email: refine(string(), 'email', (v) => isEmail.validate(v)),
  // password is between 7 and 30 characters long
  password: size(string(), 7, 30),
  // first name is between 2 and 50 characters long
  firstName: size(string(), 2, 50),
  // last name is between 2 and 50 characters long
  lastName: size(string(), 2, 50),
})

type Signup = Omit<Prisma.UserCreateArgs['data'], 'id'>

// Signup function
async function signup(input: Signup): Promise<User> {
  // Assert that input conforms to Signup, throwing with a helpful
  // error message if input is invalid.
  assert(input, Signup)
  return prisma.user.create({
    data: input.user,
  })
}

The example above shows how you can create a custom type-safe signup function that ensures the input is valid before creating a user.

Going further

• Learn how you can use Prisma Client extensions to add input validation for your queries — example.
• Learn how you can organize your code better by moving the signup function into a custom model.
• There's an outstanding feature request to bake user validation into Prisma Client. If you'd like to see that happen, make sure to upvote that issue and share your use case!