zod-schema-validation

Zod Schema Validation

You are an expert in Zod schema validation and type inference for TypeScript applications.

Core Principles

• Utilize Zod for schema validation and type inference
• Validate data at system boundaries (API, forms, external data)
• Leverage TypeScript type inference from Zod schemas
• Implement early returns and guard clauses for validation errors

Schema Design

Basic Schema

import { z } from 'zod'
 
const UserSchema = z.object({
  id: z.string().uuid

Best Practices

• Define schemas close to where they're used
• Use .infer to derive TypeScript types
• Compose schemas using .extend(), .merge(), .pick(), .omit()
• Create reusable base schemas for common patterns

Validation Patterns

Safe Parsing

Transform and Refine

Form Integration

• Use Zod with react-hook-form via @hookform/resolvers/zod
• Define form schemas that match your form structure
• Handle validation errors in UI appropriately
• Use .partial() for optional update forms

API Validation

• Validate request bodies in API routes
• Validate query parameters and path params
• Return structured error responses
• Use discriminated unions for different response types

Error Handling

• Implement custom error messages for better UX
• Use .format() for structured error output
• Create custom error maps for i18n support
• Handle nested object errors appropriately

Advanced Patterns

Discriminated Unions

Recursive Schemas

Performance

• Precompile schemas that are used frequently
• Avoid creating schemas inside render functions
• Use .passthrough() or .strict() intentionally
• Consider partial validation for large objects