gem 'swagger-dsl'

class BaseSerializer
  extend Swagger::DSL::Serializer
end

class UserSerializer < BaseSerializer
  swagger do
    id :integer
    name :string
    age :integer, minimum: 18
  end
end

class ApplicationController
  extend Swagger::DSL::RailsController
end

class UsersController < ApplicationController
  swagger :update do
    params do
      path :id, schema: :integer
      query do
        safe schema: :boolean, required: false
        redirect do
          schema do
            string!
            format! "url"
          end
        end
      end
    end

    body do
      # name :string
      # age :integer, minimum: 18
      cref! UserSerializer # "#/components/User"
    end

    render 200, dsl: :jimmy do # another json schema dsl by "jimmy" gem
      object do
        string :status, enum: %w[ok], default: :ok
        cref :user, UserSerializer
        require all
      end
    end
  end

  def update
    # some
  end
end

Swagger::DSL.current["info"] = {
  "title" => "my app",
  "version" => "0.1.0",
}

JSON.dump(Swagger::DSL.current)

if Rails.application.config.eager_load
  Swagger::DSL.current.config.lazy_define_paths = true
  Rails.application.config.after_initialize do
    Rails.application.reload_routes!
    Swagger::DSL.current.define_paths!
    JSON.dump(Swagger::DSL.current)
  end
end