@skmtc/gen-zod

A model generator. Produces export const userBody = z.object({...}) runtime schemas — the validation counterpart to gen-typescript's static types. Most production setups run them together.

Source

skmtc-generators/gen-zod/src/

What it generates

For a User schema:

import { z } from 'zod'

export const user = z.object({
  id: z.string(),
  name: z.string(),
  email: z.string().optional(),
})

Per-variant classes (ZodObject, ZodArray, ZodString, ZodInteger, ZodNumber, ZodBoolean, ZodUnion, ZodVoid, ZodUnknown) handle the dispatch. The recursive structure mirrors OasSchema.

Key decisions

• Lowercase identifier names. export const user (not User) to distinguish from the TypeScript-type equivalent User. This is the load-bearing decision that makes mixed-import rendering work (import { user, type User } from ...).
• Modifier composition via helpers. withNullable and withOptional (in src/) wrap a base schema's toString() with .nullable() / .optional() chains. The applyModifiers function applies both based on the OasSchema's flags.
• Per-variant constraint rendering. ZodConstraints.ts centralizes the per-variant constraint-rendering logic (.min(...), .max(...), .email(), .uuid(), etc.) so each variant class doesn't reimplement it.
• ZodRef is its own class. Refs aren't an OasSchema variant but they're a render case — ZodRef.ts handles the "reference to a previously-registered Zod schema" path.

What to learn from it

• The canonical schema-renderer shape. Look at ZodProjection.ts to see the toZodValue dispatch and how each variant class is invoked. The pattern transfers directly to Valibot, ArkType, or any other validation library.
• Modifier composition. The withNullable/withOptional pattern keeps the variant classes focused on their core representation; nullability and optionality wrap on top.
• Constraint rendering separated from type rendering. The split between "this is a string" (ZodString) and "this string has .min(8).max(64)" (ZodConstraints) keeps both halves readable.

Common customizations when cloned

• Add Zod features the stock doesn't render (e.g., .refine(...) predicates for custom validation).
• Map custom OpenAPI format values to Zod's specialized methods (e.g., format: 'uri' → z.string().url()).
• Change identifier casing (the lowercase decision is a customization seam — some teams prefer UserSchema over user).
• Replace z.object({...}) with z.strictObject({...}) if you want unknown-key rejection.

See also

• gen-typescript — sibling model generator; typical combo
• gen-valibot — same pattern, different library
• gen-arktype — same pattern, different library
• OasSchema variants reference — what toZodValue dispatches over
• Projections and Snippets concept