zod-4

prowler-cloud's avatarfrom prowler-cloud

Zod 4 schema validation patterns. Trigger: When using Zod for validation - breaking changes from v3.

⭐12.5kstars🔀1.9kforks📁View on GitHub🕐Updated Jan 10, 2026
[Code Generation]

When & Why to Use This Skill

This Claude skill provides comprehensive patterns and best practices for Zod 4 schema validation, specifically optimized for TypeScript environments. It helps developers seamlessly navigate breaking changes from Zod v3 to v4, offering precise syntax for primitives, complex objects, and data transformations. By providing standardized validation patterns, it ensures type safety and robust data parsing across the entire application stack, from API request handling to frontend form management.

Use Cases

  • Migrating legacy codebases from Zod v3 to v4 by identifying and replacing deprecated methods like .nonempty() with modern v4 equivalents.
  • Defining type-safe API request schemas that utilize discriminated unions for efficient handling of polymorphic data structures.
  • Implementing complex business logic validation using refinements and superRefine for scenarios like multi-field password confirmation or conditional requirements.
  • Integrating Zod schemas with React Hook Form to provide real-time, schema-based validation and standardized error messaging in web interfaces.
  • Sanitizing and coercing input data during ingestion, such as converting string-based dates or numbers into their proper TypeScript types using Zod's coercion features.
namezod-4
description>
TriggerWhen creating or updating Zod v4 schemas for validation/parsing (forms, request payloads, adapters), including v3 -> v4 migration patterns.
licenseApache-2.0
authorprowler-cloud
version"1.0"
scope[root, ui]
auto_invoke"Creating Zod schemas"
allowed-toolsRead, Edit, Write, Glob, Grep, Bash, WebFetch, WebSearch, Task

Breaking Changes from Zod 3

// ❌ Zod 3 (OLD)
z.string().email()
z.string().uuid()
z.string().url()
z.string().nonempty()
z.object({ name: z.string() }).required_error("Required")

// ✅ Zod 4 (NEW)
z.email()
z.uuid()
z.url()
z.string().min(1)
z.object({ name: z.string() }, { error: "Required" })

Basic Schemas

import { z } from "zod";

// Primitives
const stringSchema = z.string();
const numberSchema = z.number();
const booleanSchema = z.boolean();
const dateSchema = z.date();

// Top-level validators (Zod 4)
const emailSchema = z.email();
const uuidSchema = z.uuid();
const urlSchema = z.url();

// With constraints
const nameSchema = z.string().min(1).max(100);
const ageSchema = z.number().int().positive().max(150);
const priceSchema = z.number().min(0).multipleOf(0.01);

Object Schemas

const userSchema = z.object({
  id: z.uuid(),
  email: z.email({ error: "Invalid email address" }),
  name: z.string().min(1, { error: "Name is required" }),
  age: z.number().int().positive().optional(),
  role: z.enum(["admin", "user", "guest"]),
  metadata: z.record(z.string(), z.unknown()).optional(),
});

type User = z.infer<typeof userSchema>;

// Parsing
const user = userSchema.parse(data);  // Throws on error
const result = userSchema.safeParse(data);  // Returns { success, data/error }

if (result.success) {
  console.log(result.data);
} else {
  console.log(result.error.issues);
}

Arrays and Records

// Arrays
const tagsSchema = z.array(z.string()).min(1).max(10);
const numbersSchema = z.array(z.number()).nonempty();

// Records (objects with dynamic keys)
const scoresSchema = z.record(z.string(), z.number());
// { [key: string]: number }

// Tuples
const coordinatesSchema = z.tuple([z.number(), z.number()]);
// [number, number]

Unions and Discriminated Unions

// Simple union
const stringOrNumber = z.union([z.string(), z.number()]);

// Discriminated union (more efficient)
const resultSchema = z.discriminatedUnion("status", [
  z.object({ status: z.literal("success"), data: z.unknown() }),
  z.object({ status: z.literal("error"), error: z.string() }),
]);

Transformations

// Transform during parsing
const lowercaseEmail = z.email().transform(email => email.toLowerCase());

// Coercion (convert types)
const numberFromString = z.coerce.number();  // "42" → 42
const dateFromString = z.coerce.date();      // "2024-01-01" → Date

// Preprocessing
const trimmedString = z.preprocess(
  val => typeof val === "string" ? val.trim() : val,
  z.string()
);

Refinements

const passwordSchema = z.string()
  .min(8)
  .refine(val => /[A-Z]/.test(val), {
    message: "Must contain uppercase letter",
  })
  .refine(val => /[0-9]/.test(val), {
    message: "Must contain number",
  });

// With superRefine for multiple errors
const formSchema = z.object({
  password: z.string(),
  confirmPassword: z.string(),
}).superRefine((data, ctx) => {
  if (data.password !== data.confirmPassword) {
    ctx.addIssue({
      code: z.ZodIssueCode.custom,
      message: "Passwords don't match",
      path: ["confirmPassword"],
    });
  }
});

Optional and Nullable

// Optional (T | undefined)
z.string().optional()

// Nullable (T | null)
z.string().nullable()

// Both (T | null | undefined)
z.string().nullish()

// Default values
z.string().default("unknown")
z.number().default(() => Math.random())

Error Handling

// Zod 4: Use 'error' param instead of 'message'
const schema = z.object({
  name: z.string({ error: "Name must be a string" }),
  email: z.email({ error: "Invalid email format" }),
  age: z.number().min(18, { error: "Must be 18 or older" }),
});

// Custom error map
const customSchema = z.string({
  error: (issue) => {
    if (issue.code === "too_small") {
      return "String is too short";
    }
    return "Invalid string";
  },
});

React Hook Form Integration

import { useForm } from "react-hook-form";
import { zodResolver } from "@hookform/resolvers/zod";

const schema = z.object({
  email: z.email(),
  password: z.string().min(8),
});

type FormData = z.infer<typeof schema>;

function Form() {
  const { register, handleSubmit, formState: { errors } } = useForm<FormData>({
    resolver: zodResolver(schema),
  });

  return (
    <form onSubmit={handleSubmit(onSubmit)}>
      <input {...register("email")} />
      {errors.email && <span>{errors.email.message}</span>}
    </form>
  );
}