JSON Schema

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Introduction

Introduction

Sometimes you are interested in generating a JSON schema from a schema definition.

import * as z from "zod";

export const postSchema = z.object({
  id: z.uuid(),
  authorId: z.string(),
  title: z.string(),
  content: z.string().nullable(),
  createdAt: z.date(),
  updatedAt: z.date().nullable(),
  published: z.date().nullable(),
});

export type Post = z.infer<typeof postSchema>;

Zod provides z.fromJSONSchema() to convert a JSON Schema into a Zod schema.

const jsonSchema = z.toJSONSchema(postSchema);
console.log(jsonSchema);

{
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  type: "object",
  properties: {
    id: {
      type: "string",
      format: "uuid",
      pattern: "^([0-9a-fA-F]{8}-[0-9a-fA-F]{4}-[1-8][0-9a-fA-F]{3}-[89abAB][0-9a-fA-F]{3}-[0-9a-fA-F]{12}|00000000-0000-0000-0000-000000000000|ffffffff-ffff-ffff-ffff-ffffffffffff)$"
    },
    authorId: { type: "string" },
    title: { type: "string" },
    content: { anyOf: [ { type: "string" }, { type: "null" } ] }
  },
  required: [ "id", "authorId", "title", "content" ],
  additionalProperties: false
}

All schema & checks are converted to their closest JSON Schema equivalent.

`unrepresentable`

The following APIs are not representable in JSON Schema. By default, Zod will throw an error if they are encountered. It is unsound to attempt a conversion to JSON Schema; you should modify your schemas as they have no equivalent in JSON. An error will be thrown if any of these are encountered.

z.bigint(); // ❌
z.int64(); // ❌
z.symbol(); // ❌
z.undefined(); // ❌
z.void(); // ❌
z.date(); // ❌
z.map(); // ❌
z.set(); // ❌
z.transform(); // ❌
z.nan(); // ❌
z.custom(); // ❌

See the unrepresentable section for more information on handling these cases.

Zod - JSON Schema

Introduction

unrepresentable

`unrepresentable`