json-schema-validator: A Java repository from fdutton

This is a Java implementation of the JSON Schema Core Draft v4, v6, v7, v2019-09 and v2020-12(partial) specification for JSON schema validation. In addition, it also works for OpenAPI 3.0 request/response validation with some configuration flags. For users who want to collect information from a JSON node based on the schema, the walkers can help. The default JSON parser is the Jackson that is the most popular one. As it is a key component in our light-4j microservices framework to validate request/response against OpenAPI specification for light-rest-4j and RPC schema for light-hybrid-4j at runtime, performance is the most important aspect in the design.

Why this library

Performance

It is the fastest Java JSON Schema Validator as far as I know. Here is the testing result compare with the other two open-source implementations. It is about 32 times faster than the Fge and five times faster than the Everit.

fge: 7130ms
everit-org: 1168ms
networknt: 223ms

You can run the performance tests for three libraries from https://github.com/networknt/json-schema-validator-perftest

Parser

It uses Jackson that is the most popular JSON parser in Java. If you are using Jackson parser already in your project, it is natural to choose this library over others for schema validation.

YAML Support

The library works with JSON and YAML on both schema definitions and input data.

OpenAPI Support

The OpenAPI 3.0 specification is using JSON schema to validate the request/response, but there are some differences. With a configuration file, you can enable the library to work with OpenAPI 3.0 validation.

Dependency

Following the design principle of the Light Platform, this library has minimum dependencies to ensure there are no dependency conflicts when using it.

Here are the dependencies.

<dependency>
    <groupId>com.fasterxml.jackson.core</groupId>
    <artifactId>jackson-databind</artifactId>
    <version>${version.jackson}</version>
</dependency>

<dependency>
    <groupId>org.slf4j</groupId>
    <artifactId>slf4j-api</artifactId>
    <version>${version.slf4j}</version>
</dependency>

Note: Apache commons lang is included as a compile time dependency but is not required anymore. It is still included for the sake of older projects that depend on it as an accidental transitive runtime dependency. It is encouraged to exclude it as shown below and will be removed in a future release.

Community

This library is very active with a lot of contributors. New features and bug fixes are handled quickly by the team members. Because it is an essential dependency of the light-4j framework in the same GitHub organization, it will be evolved and maintained along with the framework.

Prerequisite

The library supports Java 8 and up. If you want to build from the source code, you need to install JDK 8 locally. To support multiple version of JDK, you can use SDKMAN

Dependency

This package is available on Maven central.

Maven:

<dependency>
    <groupId>com.networknt</groupId>
    <artifactId>json-schema-validator</artifactId>
    <version>1.0.79</version>
    <exclusions>
        <exclusion>
            <groupId>org.apache.commons</groupId>
            <artifactId>commons-lang3</artifactId>
        </exclusion>
    </exclusions>
</dependency>

Gradle:

dependencies {
    compile(group: 'com.networknt', name: 'json-schema-validator', version: '1.0.79');
}

For the latest version, please check the release page.

Quick Start

Validators

Configuration

Specification Version

YAML Validation

Schema Mapping

Customized URIFetcher

Customized MetaSchema

Collector Context

JSON Schema Walkers and WalkListeners

ECMA-262 Regex

Custom Message

Multiple Language

MetaSchema Validation

Validating RFC 3339 durations

Known issues

I have just updated the test suites from the official website as the old ones were copied from another Java validator. Now there are several issues that need to be addressed. All of them are edge cases, in my opinion, but need to be investigated. As my old test suites were inherited from another Java JSON Schema Validator, I guess other Java Validator would have the same issues as these issues are in the Java language itself.

Projects

The light-rest-4j, light-graphql-4j and light-hybrid-4j use this library to validate the request and response based on the specifications. If you are using other frameworks like Spring Boot, you can use the OpenApiValidator, a generic OpenAPI 3.0 validator based on the OpenAPI 3.0 specification.

If you have a project using this library, please submit a PR to add your project below.

Contributors

Thanks to the following people who have contributed to this project. If you are using this library, please consider to be a sponsor for one of the contributors.