class Grape::Middleware::Filter

use Grape::Middleware::Filter, before: -> { do_something }, after: -> { do_something }
to Grape APIs. It is used like so:
This is a simple middleware for adding before and after filters

def after 

def after
  app.instance_eval(&options[:after]) if options[:after]
end

def before 

def before
  app.instance_eval(&options[:before]) if options[:before]
end