@amritk/generate-validators

Programmatic API for generating predicate-style TypeScript validators from JSON Schemas.

Overview

@amritk/generate-validators produces lightweight runtime validators from a JSON Schema. Where @amritk/generate-parsers coerces and parses unknown input into a typed value, this package emits cheaper predicate-style functions that simply tell you whether a value matches a schema (and where it doesn't).

Each generated file exports:

• A TypeScript type definition for the schema
• A validateFoo(input: unknown, _path?: string): ValidationResult function

A shared validation-result.ts template and an index.ts barrel are emitted alongside the generated files.

Installation

npm install @amritk/generate-validators
# or
pnpm add @amritk/generate-validators
# or
yarn add @amritk/generate-validators
# or
bun add @amritk/generate-validators

Usage

import { buildValidatorSchema } from '@amritk/generate-validators'
import type { JSONSchema } from 'json-schema-typed/draft-2020-12'

const schema: JSONSchema = {
  type: 'object',
  properties: {
    info: { $ref: '#/$defs/info' },
  },
  $defs: {
    info: {
      type: 'object',
      properties: { title: { type: 'string' } },
      required: ['title'],
    },
  },
}

const files = await buildValidatorSchema(schema, 'Document')
// → [{ filename: 'document.ts', content: '...' }, { filename: 'info.ts', ... }, { filename: 'validation-result.ts', ... }, { filename: 'index.ts', ... }]

Write the resulting files to disk and import the validators where you need them:

import { validateDocument } from './generated'

const result = validateDocument(input)
if (!result.valid) {
  console.error(result.errors)
}

API

buildValidatorSchema(rootSchema, rootTypeName)

| Parameter | Type | Description | |:---|:---|:---| | rootSchema | JSONSchema | The root schema to traverse. $ref and $dynamicRef are resolved recursively. Draft-07 schemas are upgraded to 2020-12 automatically. | | rootTypeName | string | Name used for the root type (e.g. "Document"). |

Returns: Promise<GeneratedFile[]> where GeneratedFile = { filename: string; content: string }.

Related packages

• @amritk/generate-parsers — type definitions plus parsers that coerce input
• @amritk/mjst — CLI wrapper around the generators
• @amritk/helpers — shared schema-traversal utilities

License

MIT