Gemfile
gem 'grape' gem 'grape-jbuilder'
Grape
https://github.com/ruby-grape/grape#reloading-in-rails-applications
Grape-jbuilder
https://github.com/milkcocoa/grape-jbuilder
提示: 文件名小写，类名大写“‘ruby
app/api/twitter/apiv1.rb module Twitter class APIV1 < Grape::API end end