Prepare

In our settings (lib/bookshelf.rb), there is code block that allows to share the code for all the mailers of our application. When a mailer includes the Hanami::Mailer module, that block code is yielded within the context of that class. This is heavily inspired by Ruby Module and its included hook.

Imagine we want to set a default sender for all the mailers. Instead of specifying it for each mailer, we can use a DRY approach.

We create a module:

# lib/mailers/default_sender.rb
module Mailers
  module  DefaultSender
    def self.included(mailer)
      mailer.class_eval do
        from 'sender@bookshelf.org'
      end
    end
  end
end

Then we include in all the mailers of our application, via prepare.

# lib/bookshelf.rb
# ...
Hanami.configure do
  # ...
  mailer do
    root 'lib/bookshelf/mailers'
    # See https://guides.hanamirb.org/mailers/delivery
    delivery :test
    prepare do
      include Mailers::DefaultSender
    end
  end
end

Code included via prepare is available for ALL the mailers of an application.