grape-swagger

What is grape-swagger?

The grape-swagger gem provides an autogenerated documentation for your Grape API. The generated documentation is Swagger-compliant, meaning it can easily be discovered in Swagger UI. You should be able to point the petstore demo to your API.

Demo Screenshot

Installation

Add to your Gemfile:

gem 'grape-swagger'

Upgrade

Please see UPGRADING when upgrading from a previous version.

Usage

Mount all your different APIs (with Grape::API superclass) on a root node. In the root class definition, include add_swagger_documentation, this sets up the system and registers the documentation on '/swagger_doc.json'. See example/api.rb for a simple demo.

require 'grape-swagger'

module API
  class Root < Grape::API
    mount API::Cats
    mount API::Dogs
    mount API::Pirates
    add_swagger_documentation
  end
end

To explore your API, either download Swagger UI and set it up yourself or go to the online swagger demo and enter your localhost url documentation root in the url field (probably something in the line of http://localhost:3000/swagger_doc.json).

CORS

If you use the online demo, make sure your API supports foreign requests by enabling CORS in Grape, otherwise you'll see the API description, but requests on the API won't return. Use rack-cors to enable CORS.

require 'rack/cors'
use Rack::Cors do
  allow do
    origins '*'
    resource '*', headers: :any, methods: [ :get, :post, :put, :delete, :options ]
  end
end
```

Alternatively you can set CORS headers in a Grape `before` block.

``` ruby
before do
  header['Access-Control-Allow-Origin'] = '*'
  header['Access-Control-Request-Method'] = '*'
end

Configure

You can pass a hash with optional configuration settings to add_swagger_documentation.

target_class

The API class to document, default self.

mount_path

The path where the API documentation is loaded, default is /swagger_doc.

class_name

API class name.

markdown

Allow markdown in notes, default is nil. (disabled) See below for details.

hide_format

Don't add .(format) to the end of URLs, default is false.

api_version

Version of the API that's being exposed.

base_path

Base path of the API that's being exposed. This configuration parameter accepts a proc to evaluate base_path, useful when you need to use request attributes to determine its value.

authorizations

This value is added to the authorizations key in the JSON documentation.

root_base_path

Add basePath key to the JSON documentation, default is true.

models

A list of entities to document. Combine with the grape-entity gem. See below for details.

hide_documentation_path

Don't show the /swagger_doc path in the generated swagger documentation.

format

Documentation response format, default is :json.

info

A hash merged into the info key of the JSON documentation. This may contain:

:title: The API title to be displayed on the API homepage.
:description: A description of the API.
:contact: Contact email.
:license: The name of the license.
:license_url: The URL of the license.
:terms_of_service_url: The URL of the API terms and conditions.

api_documentation

Customize the Swagger API documentation route, typically contains a desc field. The default description is "Swagger compatible API description".

add_swagger_documentation \
   api_documentation: { desc: 'Reticulated splines API swagger-compatible documentation.' }

specific_api_documentation

Customize the Swagger API specific documentation route, typically contains a desc field. The default description is "Swagger compatible API description for specific API".

add_swagger_documentation \
   specific_api_documentation: { desc: 'Reticulated splines API swagger-compatible endpoint documentation.' }

Swagger Header Parameters

Swagger also supports the documentation of parameters passed in the header. Since grape's params[] doesn't return header parameters we can specify header parameters seperately in a block after the description.

desc "Return super-secret information", {
  headers: {
    "XAuthToken" => {
      description: "Valdates your identity",
      required: true
    },
    "XOptionalHeader" => {
      description: "Not really needed",
      required: false
    }
  }
}

Hiding an Endpoint

You can hide an endpoint by adding hidden: true in the description of the endpoint:

desc 'Hide this endpoint', hidden: true

Overriding Auto-Generated Nicknames

You can specify a swagger nickname to use instead of the auto generated name by adding :nickname 'string'`` in the description of the endpoint.

desc 'Get a full list of pets', nickname: 'getAllPets'

Grape Entities

Add the grape-entity gem to our Gemfile.

The following example exposes statuses. And exposes statuses documentation adding :type and :desc.

module API
  module Entities
    class Status < Grape::Entity
      expose :text, documentation: { type: 'string', desc: 'Status update text.' }
      expose :links, using: Link, documentation: { type: 'link', is_array: true }
      expose :numbers, documentation: { type: 'integer', desc: 'favourite number', values: [1,2,3,4] }
    end

    class Link < Grape::Entity
      def self.entity_name
        'link'
      end

      expose :href, documentation: { type: 'url' }
      expose :rel, documentation: { type: 'string'}
    end
  end

  class Statuses < Grape::API
    version 'v1'

    desc 'Statuses index', entity: API::Entities::Status
    get '/statuses' do
      statuses = Status.all
      type = current_user.admin? ? :full : :default
      present statuses, with: API::Entities::Status, type: type
    end

    desc 'Creates a new status', entity: API::Entities::Status, params: API::Entities::Status.documentation
    post '/statuses' do
        ...
    end
  end
end

Relationships

Put the full name of the relationship's class in type, leaving out any modules named Entities or Entity. So for the entity class API::Entities::Address, you would put type: 'API::Address'.

1xN

module API
  module Entities
    class Client < Grape::Entity
      expose :name, documentation: { type: 'string', desc: 'Name' }
      expose :addresses, using: Entities::Address,
        documentation: { type: 'API::Address', desc: 'Addresses.', param_type: 'body', is_array: true }
    end

    class Address < Grape::Entity
      expose :street, documentation: { type: 'string', desc: 'Street.' }
    end
  end

  class Clients < Grape::API
    version 'v1'

    desc 'Clients index', params: Entities::Client.documentation
    get '/clients' do
      ...
    end
  end

  add_swagger_documentation models: [Entities::Client, Entities::Address]
end

1x1

Note: is_array is false by default.

module API
  module Entities
    class Client < Grape::Entity
      expose :name, documentation: { type: 'string', desc: 'Name' }
      expose :address, using: Entities::Address,
        documentation: { type: 'API::Address', desc: 'Addresses.', param_type: 'body', is_array: false }
    end

    class Address < Grape::Entity
      expose :street, documentation: { type: 'string', desc: 'Street' }
    end
  end

  class Clients < Grape::API
    version 'v1'

    desc 'Clients index', params: Entities::Client.documentation
    get '/clients' do
      ...
    end
  end

  add_swagger_documentation models: [Entities::Client, Entities::Address]
end

Markdown in Notes

The grape-swagger gem allows you to add an explanation in markdown in the notes field. Which would result in proper formatted markdown in Swagger UI. Grape-swagger uses adapters for several markdown formatters. It includes adapters for kramdown (kramdown syntax) and redcarpet. The adapters are packed in the GrapeSwagger::Markdown modules. We do not include the markdown gems in our gemfile, so be sure to include or install the depended gems.

Kramdown

If you want to use kramdown as markdown formatter, you need to add kramdown to your gemfile.

gem 'kramdown'

Configure your api documentation route with:

add_swagger_documentation(
  markdown: GrapeSwagger::Markdown::KramdownAdapter
)

Finally you can write endpoint descriptions the with markdown enabled.

desc "Reserve a burger in heaven", {
  notes: <<-NOTE
    Veggie Burgers in Heaven
    -----------------

    > A veggie burger doesn't come for free

    If you want to reserve a veggie burger in heaven, you have to do
    some crazy stuff on earth.

        def do_good
          puts 'help people'
        end

    * _Will go to Heaven:_ Probably
    * _Will go to Hell:_ Probably not
  NOTE
}

Redcarpet

As alternative you can use redcarpet as formatter, you need to include redcarpet in your gemspec. If you also want to use rouge as syntax highlighter you also need to include it.

gem 'redcarpet'
gem 'rouge'