Ruby JSON Schema Validator

This library is intended to provide Ruby with an interface for validating JSON objects against a JSON schema conforming to JSON Schema Draft 3. The project originally started as a fork of Constellation’s ruby-jsonschema project, but differences in the JSON schema draft versions implemented as well as assumptions made by the ruby-jsonschema library forced this to become a new project.

This project is far from complete but is in a somewhat usable state…



gem install json-schema

If downloading the git repo, build the gem and install it:

$ rake package
$ gem install pkg/json-schema-0.1.0.gem

require 'rubygems'
require 'json-schema'

JSON::Validator.validate('schema.json', 'data.json')

schema = {
  "properties" => {
    "a" => {"type" => "integer"}

data = {
  "a" => 5

JSON::Validator.validate(schema, data)

Currently implemented

The following core schema definitions are currently implemented:

  • type
  • properties
  • patternProperties
  • additionalProperties
  • items
  • additionalItems
  • required
  • dependencies
  • minimum
  • maximum
  • exclusiveMinimum
  • exclusiveMaximum
  • minItems
  • maxItems
  • uniqueItems
  • pattern
  • minLength
  • maxLength
  • enum
  • title
  • description
  • divisibleBy
  • disallow
  • extends
  • id
  • $ref (this implementation only follows slash-delimited fragment resolution)

Not implemented

The following core schema definitions are not implemented:

  • default – This library aims to solely be a validator and does not modify an object it is validating.
  • $schema – Support for this will come later, possibly with the ability to validate against other JSON Schema draft versions

In addition, the following hyper schema attributes are not implemented at this time:

  • links (not much to do with validation…)
  • fragmentResolution (only handles default slash-delimited)
  • readonly
  • contentEncoding
  • pathStart
  • mediaType

To Do

  • Massive re-factoring – the whole validation process needs to be broken down into something a bit more manageable
  • (Much) More testing
  • Better interface to validator to allow for error messages in validation to propogate