json-schema.md

JSON Schema

Every schema exports a JSON Schema fragment via toJsonSchema(). The config-object API maps almost 1:1 onto JSON Schema, so the export is direct and round-trippable for OpenAPI / Swagger generation.

import { t } from '@myrialabs/typkit';

const User = t.object({
  id: t.int().min(1),
  name: t.string().minLength(2).maxLength(40),
  email: t.string().email(),
  role: t.enum(['admin', 'user']).default('user'),
  bio: t.string().maxLength(280).optional(),
});

User.toJsonSchema();

produces:

{
  "type": "object",
  "properties": {
    "id": { "type": "integer", "minimum": 1 },
    "name": { "type": "string", "minLength": 2, "maxLength": 40 },
    "email": { "type": "string", "format": "email" },
    "role": { "enum": ["admin", "user"], "default": "user" },
    "bio": { "type": "string", "maxLength": 280 }
  },
  "required": ["id", "name", "email"]
}

Mapping

TypKit	JSON Schema
t.string({ minLength, maxLength })	{ type: 'string', minLength, maxLength }
t.string({ charset }) / { pattern }	{ pattern }
t.email(), t.uuid(), t.url(), format	{ format } (datetime → date-time)
t.number({ min, max })	{ minimum, maximum }
t.number({ greaterThan, lessThan })	{ exclusiveMinimum, exclusiveMaximum }
t.int()	{ type: 'integer' }
t.object({...})	{ type: 'object', properties, required }
t.array(el, { minItems })	{ type: 'array', items, minItems }
t.enum([...])	{ enum: [...] }
t.literal(v)	{ const: v }
t.union(...)	{ anyOf: [...] }
t.discriminatedUnion(k, [...])	{ oneOf: [...] }
t.intersection(a, b)	{ allOf: [a, b] }
t.optional(x)	property omitted from required
t.nullable(x)	{ anyOf: [x, { type: 'null' }] }
t.default(x, v)	{ ...x, default: v }
t.record(v)	{ type: 'object', additionalProperties: v }
.strict() / .passthrough()	additionalProperties: false / true

Notes

• A few inline string constraints (maxLines, blockWords, allowedWords) have no JSON Schema equivalent and are validated only at runtime; they are omitted from the exported schema rather than approximated.
• toJsonSchema() is a method on every node, including nested ones, so you can export any sub-schema.