Unified Validation

This 'Unified Validation' library is bridges the gap between server side validation in Java, usuing the JSR303 standard, and front end validation in javascript using json-schema (json-schema.org). In order to do this, greater control over the JSR303 side is needed than is available through its standard API, so this implementation is specific to the Hibernate Bean Validation implementation.

The following capabilities are addressed:

• A json-schema can be converted into a JSR303 Validator.
• Validations specified in json-schema can be overlayed on top of validations already defined with JSR303 annotations, XML configuration or using Hibernates programmatic API to specify validations.
• Multiple json-schemas can be stacked together to produce a single validation.
• A Bean Validation configuration can be converted into a json-schema.

The goal is to be able to build a validation from a combination of JSR303 annotations and json-schemas, stack those together to produce a complete validation and then to be able to check that validation using either JSR303, or a json-schema validator.

Build it

Once you have obtained the source code:

> mvn clean install

Use it

A fluent API exists to help with building json-schemas in code. For example:

JsonSchema minValueSchema = JsonSchema.object().property("testInt").minimum(1).build();

The JsonSchema object can also be deserialized from JSON using Jackson or gson in the usual way.

A Validator can be constructed, that adds the validations defined in json-schemas on top of the validations defined using annotations, XML or Hibernates programmatic API, with the JsonSchemaValidatorFactory. Here is an example:

JsonSchemaValidatorFactory.ValidatorBuilder builder = validatorFactory.getBuilder();
builder.addSchema(myBean.getClass(), schema);

Validator validator = builder.build();

This Validator can then be used to perform server side validation in the usual way:

Set<ConstraintViolation> errors = validator.validate(myBean);

Roadmap

• Translation of regular expressions between Java and ECMA 262 notation.
• Correct serialization/deserialization of the internal JsonSchema into JSON Schema representation.
• Support for the remaining keywords in JSON Schema.

JSON Schema features supported.

Keyword	Comments
minimum	supported
exclusiveMinimum	supported
maximum	supported
exclusiveMaximum	supported
maxLength	supported
minLength	supported
pattern	Only where the regex is valid in both Java and ECMA 262 notation
additionalItems
maxItems
minItems
uniqueItems
maxProperties
minProperties
required
additionalProperties
properties
patternProperties
dependencies
enum
type
allOf
anyOf
oneOf
not
title
description
default
format
date-time
email
hostname
ipv4
ipv6
uri

JSR303 features supported.