OpenAPI Parser

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This is OpenAPI3 parser and validator.


root = OpenAPIParser.parse(YAML.load_file('open_api_3/schema.yml'))

# request operation combine path parameters and OpenAPI3's Operation Object
request_operation = root.request_operation(:post, '/validate')

ret = request_operation.validate_request_body('application/json', {"integer" => 1})
# => {"integer" => 1}

# invalid parameter
request_operation.validate_request_body('application/json', {"integer" => '1'})
# => OpenAPIParser::ValidateError: 1 class is String but it's not valid integer in #/paths/~1validate/post/requestBody/content/application~1json/schema/properties/integer

# path parameter
request_operation = root.request_operation(:get, '/path_template_test/1')
# => {"template_name"=>"1"}

# coerce parameter
root = OpenAPIParser.parse(YAML.load_file('open_api_3/schema.yml'), {coerce_value: true, datetime_coerce_class: DateTime}) 
request_operation = root.request_operation(:get, '/string_params_coercer') 
request_operation.validate_request_parameter({'integer_1' => '1', 'datetime_string' => '2016-04-01T16:00:00+09:00'})
# => {"integer_1"=>1, "datetime_string"=>#<DateTime: 2016-04-01T16:00:00+09:00 ((2457480j,25200s,0n),+32400s,2299161j)>
# convert number string to Integer and datetime string to DateTime class


Add this line to your application's Gemfile:

gem 'openapi_parser'

And then execute:

$ bundle

Or install it yourself as:

$ gem install openapi_parser

Additional features

OpenAPI Parser's validation based on OpenAPI spec
But we support few useful features.

type validation

We support additional type validation.

type format description
string uuid validate uuid string. But we don't check uuid layout

Reference Validation on Schema Load

Invalid references (missing definitions, typos, etc.) can cause validation to fail in runtime, and these errors can be difficult to debug (see:

Pass the strict_reference_validation: true option to detect invalid references. An OpenAPIError::MissingReferenceError exception will be raised when a reference cannot be resolved.

If the expand_reference configuration is explicitly false (default is true), then this configuration has no effect.

DEPRECATION NOTICE: To maintain compatibility with the previous behavior, this version sets false as a default. This behavior will be changed to true in a later version, so you should explicitly pass strict_reference_validation: false if you wish to keep the old behavior (and please let the maintainers know your use-case for this configuration!).

yaml_file = YAML.load_file('open_api_3/schema_with_broken_references.yml')
options = {
  coerce_value: true,
  datetime_coerce_class: DateTime,
  # This defaults to false (for now) - passing `true` provides load-time validation of refs
  strict_reference_validation: true

# Will raise with OpenAPIParser::MissingReferenceError
OpenAPIParser.parse(yaml_file, options)


  • correct schema checker
  • more detailed validator


After checking out the repo, run bin/setup to install dependencies. Then, run rake spec to run the tests. You can also run bin/console for an interactive prompt that will allow you to experiment.

To install this gem onto your local machine, run bundle exec rake install. To release a new version, update the version number in version.rb, and then run bundle exec rake release, which will create a git tag for the version, push git commits and tags, and push the .gem file to


Bug reports and pull requests are welcome on GitHub at This project is intended to be a safe, welcoming space for collaboration, and contributors are expected to adhere to the Contributor Covenant code of conduct.


The gem is available as open source under the terms of the MIT License.

Code of Conduct

Everyone interacting in the OpenAPIParser project’s codebases, issue trackers, chat rooms and mailing lists is expected to follow the code of conduct.