SJOT: Schemas for JSON Objects

by Robert van Engelen, Genivia Inc, engelen@genivia.com

What is SJOT?

Schemas for JSON Objects, or simply SJOT, is a much simpler alternative to JSON schema. SJOT schemas are valid JSON, just like JSON schema. But SJOT schemas have the look and feel of an object template and are readable and understandable by humans. SJOT aims at quick JSON data validation with lightweight schemas and compact validators.

Live demo at http://genivia.com/get-sjot.html#demo

JSON validation JS API

Example usage:

// <script src="sjot.js"></script>    add this to your web page to load sjot.js
var SJOT = require("sjot");     //    or use the npm sjot package for node.js

var schema = { "Data": { "id": "string", "v": "number", "tags?": "string{1,}" } };

var data = { "id": "SJOT", "v": 1.0, "tags": [ "JSON", "SJOT" ] };

// SJOT.valid(data [, type [, schema ] ]) tests if data is valid:

if (SJOT.valid(data, "#Data", schema))
  ... // OK: data validated against schema

if (SJOT.valid(data, "http://example.com/sjot.json#Data"))
  ... // OK: data validated against schema type Data from http://example.com/sjot.json

if (SJOT.valid(data))
  ... // OK: self-validated data against its embedded @sjot schema (only if a @sjot is present in data)

// SJOT.validate(data [, type [, schema ] ]) validates data, if validation fails throws an exception with diagnostics:
try {
  SJOT.validate(data, "#Data", schema);
} catch (e) {
  window.alert(e); // FAIL: validation failed
}

// SJOT.check(schema) checks if schema is compliant and correct, if not throws an exception with diagnostics:
try {
  SJOT.check(schema);
} catch (e) {
  window.alert(e); // FAIL: schema is not compliant or correct
}

sjot.js is fully functional to validate JSON data, but the current version has some limitations:

No external type references "URI#type" yet (where URI is a URL of a schema to load)
No regex property name "(regex)" matching yet (but regex types are OK!).

Three alternative versions of sjot.js are included:

sjot-fast.js is optimized for speed but validation error messages are less informative
sjot-lean.js is optimized for size but lacks SJOT.check(schema)
sjot-mean.js is optimized for speed and size

JSON validation C/C++ API

sjot.c and sjot.cpp initial release for gSOAP is expected in October 2016.

Feature wish list / nice to have

SJOT to JSON schema converter
JSON schema to SJOT converter

Changelog