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(),
  email: z.string().email(),
  name: z.string().min(1).max(100),
  age: z.number().int().positive().optional(),
  role: z.enum(['admin', 'user', 'guest']),
  createdAt: z.date(),
})

type User = z.infer<typeof UserSchema>

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

const result = UserSchema.safeParse(data)
if (!result.success) {
  console.error(result.error.format())
  return
}
// result.data is typed as User