Sharing ruby code for Sinatra::Base & Sinatra::Application classes

Question

I am quite new with Sinatra framework and I am trying to do a gem compatible with Sinatra::Base & Sinatra::Application based apps. I have this code in my gem and it is working fine in both apps:

health_check.rb

class App1 < Sinatra::Base
  get '/health/liveness' do
    halt 204
  end
end

class App2 < Sinatra::Application
  get '/health/liveness' do
    halt 204
  end
end

But I the code is repeated and I would like to have something like this, but it does not work:

health_check.rb

module HealthHelper
  get '/health/liveness' do
    halt 204
  end
end

class App1 < Sinatra::Base
  include HealthHelper
end

class App2 < Sinatra::Application
  include HealthHelper
end

When I try to init any app with the gem included I get this error

/lib/health_check.rb:3:in `<module:HealthHelper>': undefined method `get' for HealthHelper:Module (NoMethodError)
Did you mean?  gets
               gem

Any idea to make it cleaner?

Answer 1

Rather than simply using include, you can write a Sinatra extension that defines the routes.

It might look something like this:

require 'sinatra/base'

module HealthHelper
  def self.registered(app)
    app.get '/health/liveness' do
      halt 204
    end
  end
end

# This line is so it will work in classic Sinatra apps.
Sinatra.register(HealthHelper)

Then in your actual apps, you use register instead of include:

require 'sinatra/base'
require 'health_helper'

class App1 < Sinatra::Base
  register HealthHelper
end

Now the routes will be available in App1. Note that you probably don’t want to be extending Sinatra::Application, but rather Sinatra::Base.