Tiny Validator for v4 JSON Schema

Tiny Validator is a JavaScript library for validation against v4 the JSON Schema standard.

It supports $ref with JSON Pointer fragment paths (e.g. http://example.com/schema#/properties/myKey).

It uses relatively modern JavaScript features (such as JSON.stringify and Array.isArray) so older browsers will need a compatability shim - this is a good one.

For the source code, see the GitHub repository.

Usage:

There are three methods for validating data:

var valid = tv4.validate(data, schema);

The first form returns the validation state as the value from the function, making an object describing the error available as tv4.error. (Note this is not suitable for multi-threaded environments.)

var resultObj = tv4.validateResult(data, schema);

The second form returns an object containing the validation state (resultObj.valid), and any error (resultObj.error).

var resultObj = tv4.validateMultiple(data, schema);

The third form is similar to the second, except instead of stopping when the first validation error is encountered, it collects an array of errors, returning it in resultObj.errors.

Missing schemas

If there are any schemas missing ($refs not resolved), then they will be present in tv4.missing (or resultObj.missing). For the purposes of validation, missing schemas are treated as empty.

Errors and error codes

The validation error objects include an error code, corresponding to a key in tv4.errorCodes (e.g. tv4.errorCodes.ENUM_MISMATCH = 1).

The error objects also include a human-readable message in error.message, and a JSON Pointer path to the relevant part of the data/schema (error.dataPath and error.schemaPath).

Demos:

Basic usage

var schema = {
	"items": {
		"type": "boolean"
	}
};
var data1 = [true, false];
var data2 = [true, 123];

alert("data 1: " + tv4.validate(data1, schema)); // true
alert("data 2: " + tv4.validate(data2, schema)); // false
alert("data 2 error: " + JSON.stringify(tv4.error, null, 4));

Use of $ref

var schema = {
	"type": "array",
	"items": {"$ref": "#"}
};
var data1 = [[], [[]]];
var data2 = [[], [true, []]];

alert("data 1: " + tv4.validate(data1, schema)); // true
alert("data 2: " + tv4.validate(data2, schema)); // false

Missing schema

var schema = {
	"type": "array",
	"items": {"$ref": "http://example.com/schema"}
};
var data = [1, 2, 3];

alert("Valid: " + tv4.validate(data, schema)); // true
alert("Missing schemas: " + JSON.stringify(tv4.missing));

Referencing remote schema

tv4.addSchema("http://example.com/schema", {
	"definitions": {
		"arrayItem": {"type": "boolean"}
	}
});
var schema = {
	"type": "array",
	"items": {"$ref": "http://example.com/schema#/definitions/arrayItem"}
};
var data1 = [true, false, true];
var data2 = [1, 2, 3];

alert("data 1: " + tv4.validate(data1, schema)); // true
alert("data 2: " + tv4.validate(data2, schema)); // false

Asynchronous usage:

Asynchronous usage (fetching schemas using AJAX) requires an additional file. Currently, the only version available relies on jQuery, but it is short and should be easily modifiable for other libraries: tv4.async-jquery.js

Asynchronous mode is signified by providing a callback as a third parameter:

tv4.validate(data, schema, function (isValid, validationError) { ... });

The value of validationError is taken from tv4.error.

Tests:

There are some tests, but they use PHP to run, so they won't work when hosted by GitHub.