zod-to-form-core

name	zod-to-form-core
description	Schema walker and processor registry for Zod v4 form generation Use when: You want per-field validation instead of whole-form validation. Also: zod, zod-v4, forms, form-generation, schema, schema-walker, processor-registry, react-hook-form, schema-driven, form-schema, zod-registry.
license	MIT

@zod-to-form/core

Schema walker and processor registry for Zod v4 form generation

Requires Zod v4 — uses _zod.def, _zod.bag, and z.registry() APIs. Does NOT work with Zod v3 (which uses _def internals).

Key concepts:

• Processors: Per-type handlers that extract structure from Zod schemas
• Registry: z.registry<FormMeta>() stores per-schema field config
• Optimization: L1 decomposes validation per-field, L2 extracts native HTML rules
• Config presets: shadcn preset maps to controlled components with field expressions

Quick Start

import { z } from 'zod';
import { walkSchema } from '@zod-to-form/core';

const schema = z.object({
  name: z.string().min(1).describe('Your full name'),
  age: z.number().int().min(0),
  newsletter: z.boolean().default(false)
});

const fields = walkSchema(schema);

console.log(fields.map((f) => ({ key: f.key, component: f.component })));

When to Use

Use this skill when:

• You want per-field validation instead of whole-form validation → use createOptimizers
• You need native HTML validation attributes (required, minLength, pattern) → use createOptimizers
• You want TypeScript inference and IDE autocompletion for config → use defineConfig — defineConfig is the typed entry point; bare object literals lose generic inference on components.overrides
• Loading config from JSON files or dynamic import() where the type is unknown → use validateConfig — validates and narrows to ZodFormsConfig
• ALWAYS call on form values before schema.safeParse() in runtime mode → use normalizeFormValues — HTML inputs produce "" for unset optional fields, which Zod rejects; this is the single mandatory normalization step
• You need direct schema-to-fields conversion in runtime contexts → use walkSchema
• You're building a custom codegen pipeline on top of FormField[] → use walkSchema
• You have a deeply-nested FieldConfig mirroring your schema shape → use registerDeep
• Recommended for complex schemas with nested objects and arrays → use registerDeep
• Merging global field configs from z2f.config.ts into a registry → use registerFlat
• Your config uses dot-path notation rather than nested structure → use registerFlat

Do NOT use when:

• You only need whole-schema validation — omit the optimization option entirely (createOptimizers)
• Runtime-only usage where you pass config inline to walkSchema — defineConfig is a no-op at runtime without a preset; skip it when config comes from JSON or dynamic import (defineConfig)
• Using TypeScript with defineConfig() — type errors catch most issues at dev time; validateConfig is only needed when the config source is not type-checkable (validateConfig)
• CLI codegen mode — generated components call normalization internally; calling it again is safe (idempotent) but redundant (normalizeFormValues)
• You just want generated components — use the CLI instead (walkSchema)
• Your schema is not z.object() at the root level (walkSchema)
• For simple flat configs — registerFlat() is simpler and more direct (registerDeep)
• Don't use if your config comes from dot-path format (CLI global fields) (registerDeep)
• Your config is already nested mirroring schema shape — use registerDeep() instead (registerFlat)

API surface: 49 functions, 20 types, 4 constants

NEVER

• NEVER mutate builtinOptimizers — it's a module singleton. Always use createOptimizers(custom)
• NEVER assume custom optimizers append — they REPLACE the entire chain for that type
• NEVER assume preset props merge with your props — the entire props dict is replaced. If you set component props, you must include ALL props including the ones from the preset
• NEVER use as a type guard — it throws on invalid input, doesn't narrow; FIX: wrap in try/catch and branch on success, or check keys manually before calling
• NEVER assume extra keys cause failures — the schema uses z.object().loose(), so unrecognized keys are silently dropped not rejected; FIX: if you need strict key validation, inspect the returned config for unexpected fields manually
• NEVER rely on this for custom types (Date, File subclasses, etc.) — it only handles empty strings and FileList; FIX: normalize custom types before calling this function or in a custom resolver wrapper
• NEVER pass a non-object schema at the root — throws immediately
• NEVER bypass the processor registry for custom types — extend via options.processors
• NEVER skip normalizeFormValues() before schema.safeParse() — empty strings from HTML inputs fail optional field validation
• NEVER mix with registerFlat() on the same schema — registry entries conflict silently
• NEVER forget the structural keys (fields, arrayItems) for nested config — without them, child config is silently ignored
• NEVER mix with registerDeep() on the same schema — registry entries conflict silently
• NEVER assume numeric path segments matter — "items.0.name" and "items.2.name" resolve to the same target

Configuration

9 configuration interfaces — see references/config.md for details.

Quick Reference

Configuration: canonicalizeConfig (Serialize a CodegenConfig to a canonical string suitable for hashing into a cache key), defineConfig (Identity helper that returns its argument typed as ZodFormsConfig), validateConfig (Validates an unknown value as a ZodFormsConfig at runtime), resolveFieldConfig (Merge global field config with per-schema field config overrides), normalizeConfig (Normalize a validated config by migrating deprecated top-level fields to their canonical locations), ComponentPreset (Preset name for built-in component library mappings), ConfigDefaults (Default generation settings applied to all schemas unless overridden per-schema) Optimization: createOptimizers (Create an optimizer registry by merging custom optimizers with builtins), createSchemaLiteCollector (Create a new SchemaLiteCollector instance), FormOptimizer (An optimizer function that mutates a FormField after the processor has run), FormOptimizerContext (Context shared across all optimizers during a walkSchema run), SchemaLiteCollector (Mutable accumulator that builds a lite Zod schema for submit-time validation), builtinOptimizers (The default optimizer registry — L1 (decompose) + L2 (native rules) chains merged per type) utils: inferLabel (Convert a camelCase or snake_case key to a human-readable Title Case label) Utils: joinPath (Join a parent path and a child key with a dot separator), createBaseField (Create a base FormField with sensible defaults), getEmptyDefault (Returns a type-safe empty default value for a FormField based on its zodType and structure), normalizeFieldKey (Normalise a concrete field key to the bracket notation used in config), collectFieldSections (Collect section groupings from fields and a config override lookup) Normalization: normalizeFormValues (Normalize raw HTML form values for Zod parsing) Schema Walking: walkSchema (Walk a Zod schema and produce a FormField[] tree), WalkResult (The result returned by walkSchema() when an optimization level is specified) Registry: createProcessors (Create a custom processor registry by merging with built-in processors), builtinProcessors (The default processor registry — maps every Zod v4 def) **Registration:** registerDeep(Register a schema and all its nested fields in a registry using a path-structured FieldConfig tree),registerFlat(Register flat dot-path field configs against a schema's registry) **Processors:**processArray(Processz), processTuple (Process z), processBoolean(Processz), processMap (Process z), processSet(Processz), processCrossRef (Process a cross-reference field — a schema annotated in the form registry with refType), processDate (Process z), processEnum(Processz), processLiteral (Process z), processFallback(Fallback processor for Zod types without a dedicated handler),processFile(Processz), processNumber (Process z), processObject(Processz), processIntersection (Process z), processRecord(Processz), processString (Process z), processTemplateLiteral(Processz), processUnion (Process z), processDiscriminatedUnion(Processz), processDefault (Process z), processLazy(Processz), processNullable (Process z), processOptional(Processz), processPipe (Process z), processReadonly(Processz) Loader: loadSchema (Load a single named Zod schema export from a TypeScript or JavaScript file), loadSchemaModule (Load a schema file and return the entire module namespace, leaving the choice of which export to use to the caller), resolveSchemaExportNames (Return the sorted list of named Zod schema exports in a schema file), loadConfig (Load and validate a component config file (z2f), resolveDefaultConfigPath(Walk the standard config-file naming candidates incwdand return the first that exists),loadDefaultConfig(Load and validate the default config file fromcwd by auto-discovering standard naming candidates (z2f) Types: FormField (Intermediate representation of a single form field produced by walkSchema), FormFieldOption (An individual option in a Select, RadioGroup, or similar enum-driven component), FormFieldConstraints (Structural constraints extracted from Zod's _zod), FormProcessor(A processor function that mutates aFormFieldin-place based on the Zod schema it handles),FormProcessorContext(Runtime context passed to every processor during a walkSchema traversal),FormMeta(Per-schema annotation stored in az), ProcessParams (Optional parameters passed to each processor alongside the schema, context, and field), NativeRules (Native HTML and RHF validation rules extracted from Zod constraints), ValidationStrategy (Specifies how a field's validation is handled at submit and change time) types: FieldExpression (Known RHF field expression strings that can be used as values in props), ZodFormRegistry (Zod v4 registry parameterized with FormMeta) config: ComponentOverride (Per-component metadata override), StripIndexSignature (Strips index signatures from a type, keeping only explicitly declared keys), SHADCN_OVERRIDES (shadcn preset — Radix-based components need controlled mo...), DEFAULT_OVERRIDES (Default HTML preset — no controlled components by default) optimizers: SchemaLiteInfo (Metadata for codegen to reconstruct the lite schema in a...)

References

Load these on demand — do NOT read all at once:

• When calling any function → read references/functions.md for full signatures, parameters, and return types
• When defining typed variables or function parameters → read references/types.md
• When using exported constants → read references/variables.md
• When configuring options → read references/config.md for all settings and defaults

Links

• Repository
• Author: Pradeep Mouli [e-mail] (https://github.com/pradeepmouli)