Add support to validate a JSON Schema

[ThallesP]

Zod already has support for converting a Zod Schema to JSON Schema, but what if I want to validate whether an object is a valid JSON Schema?

[Mihailoff]

You could create a Zod schema that validates JSON Schema structure :)

import { z } from 'zod';

// Simplified JSON Schema validator (not complete)
const jsonSchemaValidator: z.ZodType<any> = z.lazy(() =>
  z.union([
    z.boolean(),
    z.object({
      type: z.enum(['null', 'boolean', 'object', 'array', 'number', 'string', 'integer']).optional(),
      properties: z.record(jsonSchemaValidator).optional(),
      items: jsonSchemaValidator.optional(),
      required: z.array(z.string()).optional(),
      additionalProperties: z.union([z.boolean(), jsonSchemaValidator]).optional(),
      minimum: z.number().optional(),
      maximum: z.number().optional(),
      // ... many more properties
    }).passthrough()
  ])
);

// Usage
try {
  const result = jsonSchemaValidator.parse(mySchema);
  console.log("Valid JSON Schema!");
} catch (e) {
  console.log("Invalid:", e);
}