zod

Zod Validation Skill

Summary

TypeScript-first schema validation library with static type inference. Define schemas once, get runtime validation and compile-time types automatically.

When to Use

• Form validation with type-safe data
• API request/response validation
• Environment variable validation
• Runtime type checking with TypeScript inference
• tRPC procedure inputs/outputs
• Database schema validation (Drizzle, Prisma)

Quick Start

import { z } from 'zod';

// Define schema
const UserSchema = z.object({
  id: z.string().uuid(),
  email: z.string().email(),
  age: z.number().min(18),
  role: z.enum(['user', 'admin'])
});

// Infer TypeScript type
type User = z.infer<typeof UserSchema>;

// Validate data
const result = UserSchema.safeParse(data);
if (result.success) {
  const user: User = result.data;
}

Primitive Types

Basic Types

import { z } from 'zod';

// String with validation
const nameSchema = z.string()
  .min(2, "Too short")
  .max(50, "Too long")
  .trim();

const emailSchema = z.string().email();
const urlSchema = z.string().url();
const uuidSchema = z.string().uuid();
const regexSchema = z.string().regex(/^[A-Z]{3}$/);

// Numbers
const ageSchema = z.number()
  .int("Must be integer")
  .positive()
  .min(0)
  .max(120);

const priceSchema = z.number()
  .positive()
  .multipleOf(0.01); // Currency precision

// Boolean
const isActiveSchema = z.boolean();

// Date
const createdAtSchema = z.date()
  .min(new Date('2020-01-01'))
  .max(new Date());

const dateStringSchema = z.string().datetime(); // ISO 8601
const dateOnlySchema = z.string().date(); // YYYY-MM-DD

Special Types

// Literal values
const roleSchema = z.literal('admin');
const statusSchema = z.literal('pending');

// Enums
const ColorEnum = z.enum(['red', 'green', 'blue']);
type Color = z.infer<typeof ColorEnum>; // 'red' | 'green' | 'blue'

const NativeEnum = z.nativeEnum(MyEnum); // For TypeScript enums

// Nullable and Optional
const optionalString = z.string().optional(); // string | undefined
const nullableString = z.string().nullable(); // string | null
const nullishString = z.string().nullish(); // string | null | undefined

// Default values
const countSchema = z.number().default(0);
const settingsSchema = z.object({
  theme: z.string().default('light'),
  notifications: z.boolean().default(true)
});