# base.rb

module API
  class Base < Grape::API
    include API::Base::Defaults
    mount API::V1::Base
  end
end


# defaults.rb
module API
  module Defaults
    extend ActiveSupport::Concern

    included do
      prefix 'api'
      default_format :json
      format :json

      helpers do
        def permitted_params
          @permitted_params ||= declared(params,
                                         include_missing: false)
        end

        def logger
          Rails.logger
        end
      end

      rescue_from ActiveRecord::RecordNotFound do |e|
        error_response(message: e.message, status: 404)
      end

      rescue_from ActiveRecord::RecordInvalid do |e|
        error_response(message: e.message, status: 422)
      end
    end
  end
end