dynamic_fields.rb

def send_custom_email email, email_translation, recipient, context_variables

  # ... 

  fields = %w|{{user.first_name}} {{user.last_name}} {{user.username}} {{user.site_name}}
             {{initiative.name}} {{initiative_methodology.name}} {{user_award.points}} {{user_award.disbursed_at}}
             {{user_award.reason}} {{user_award.message}} {{user_award.link}} {{file_upload_job.status}}|

  if recipient.present?
    fields.each do |f|
      obj = f.gsub("{{","").gsub("}}","").split('.').first
      field = f.gsub("{{","").gsub("}}","").split('.').second
      obj_instance = eval("context_variables[:#{obj}]")

      if obj_instance.respond_to?(:translation_for)
        value = obj_instance.translation_for(email_translation.locale)[field]
      else
        value = obj_instance[field]
      end    
    end
  end
 
  # ... 
end