json-schema-to-zod

Json-Schema-to-Zod

Looking for the exact opposite? Check out zod-to-json-schema

Summary

A runtime package and CLI tool to convert JSON schema (draft 4+) objects or files into Zod schemas in the form of JavaScript code. Uses Prettier for formatting.

Usage

Online

Just paste your JSON schemas here!

CLI

Installation:

npm i -g json-schema-to-zod

Example:

json-schema-to-zod -s myJson.json -t mySchema.ts

Options

Flag	Shorthand	Function
--source	-s	Source file name (required)
--target	-t	Target file name
--name	-n	The name of the schema in the output
--deref	-d	Uses json-schema-ref-parser to dereference the schema
--without-defaults	-wd	Ignore default values in the schema
--recursionDepth	-rd	Maximum depth of recursion in schema before falling back to z.any(). Defaults to 0. `
--module	-m	Force module syntax ("esm" or "cjs")

Programmatic

jsonSchemaToZod will output the full module code, including a Zod import. If you only need the Zod schema itself, try one of the parsers directly. If you need to deref your JSON schema, try awaiting jsonSchemaDereffed.

import {
  jsonSchemaToZod,
  jsonSchemaToZodDereffed,
  parseSchema,
} from "json-schema-to-zod";

const myObject = {
  type: "object",
  properties: {
    hello: {
      type: "string",
    },
  },
};

const module = jsonSchemaToZod(myObject);

const dereffed = await jsonSchemaToZodDereffed(myObject);

const schema = parseSchema(myObject);

module/dereffed =

import { z } from "zod";

export default z.object({ hello: z.string().optional() });

schema =

z.object({ hello: z.string().optional() });

At Runtime

The output of this package is not meant to be used at runtime. JSON Schema and Zod does not overlap 100% and the scope of the parsers are purposefully limited in order to help the author avoid a permanent state of chaotic insanity. As this may cause some details of the original schema to be lost in translation, it is instead recommended to use tools such as (Ajv)[https://ajv.js.org/] to validate your runtime values directly against the original JSON Schema.

That said, it's possible to use eval. Here's an example that you shouldn't use:

const zodSchema = eval(jsonSchemaToZod({ type: "string" }, { module: "cjs" }));

zodSchema.safeParse("Please just use Ajv instead");