zod-schema-validation

mindrally

•

6155 months ago

Source Raw

Best practices for Zod schema validation and type inference in TypeScript applications.

Quick Install

npxskills add mindrally/skills--skill zod-schema-validation

Instructions

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

Transform and Refine

const schema = z.string()
  .transform((val) => val.trim().toLowerCase())
  .refine((val) => val.length > 0, 'Cannot be empty')

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

const ResultSchema = z.discriminatedUnion('status', [
  z.object({ status: z.literal('success'), data: UserSchema }),
  z.object({ status: z.literal('error'), message: z.string() }),
])

Recursive Schemas

const CategorySchema: z.ZodType<Category> = z.lazy(() =>
  z.object({
    name: z.string(),
    children: z.array(CategorySchema),
  })
)

Performance

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

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