Rails middleware: redirect www.example.com to example.com (root domain), taken from http://blog.dynamic50.com/2011/02/22/redirect-all-requests-for-www-to-root-domain-with-heroku/

application.rb

config.autoload_paths += %W( #{ config.root }/lib/middleware )

production.rb

config.middleware.use "WwwMiddleware"

www_middleware.rb

# lib/middlewares/middleware.rb
class WwwMiddleware
  def initialize(app)
    @app = app
  end

  def call(env)
    request = Rack::Request.new(env)
    if request.host.starts_with?("www.")
      [301, {"Location" => request.url.sub("//www.", "//")}, self]
    else
      @app.call(env)
    end
  end

  def each(&block)
  end
end

Hello,
I would like to know what is the each block code for?

 def each(&block)
end

Could you explain?

@max without each method I got this error

[2018-08-16 19:01:45] ERROR NoMethodError: undefined method `each' for #<MyCustomElevator:0x00000005c1cca8>
	/home/john/.rvm/gems/ruby-2.2.3/gems/rack-1.6.4/lib/rack/body_proxy.rb:31:in `each'
	/home/john/.rvm/gems/ruby-2.2.3/gems/rack-1.6.4/lib/rack/body_proxy.rb:31:in `each'
	/home/john/.rvm/gems/ruby-2.2.3/gems/rack-1.6.4/lib/rack/body_proxy.rb:31:in `each'
	/home/john/.rvm/gems/ruby-2.2.3/gems/rack-1.6.4/lib/rack/body_proxy.rb:31:in `each'
	/home/john/.rvm/gems/ruby-2.2.3/gems/rack-1.6.4/lib/rack/body_proxy.rb:31:in `each'
	/home/john/.rvm/gems/ruby-2.2.3/gems/rack-1.6.4/lib/rack/body_proxy.rb:31:in `each'

You can use [] as the last response value

      [301, {"Location" => request.url.sub("//www.", "//")}, []]