module ActionMailer # Provides the option to parameterize mailers in order to share instance variable # setup, processing, and common headers. # # Consider this example that does not use parameterization: # # class InvitationsMailer < ApplicationMailer # def account_invitation(inviter, invitee) # @account = inviter.account # @inviter = inviter # @invitee = invitee # # subject = "#{@inviter.name} invited you to their Basecamp (#{@account.name})" # # mail \ # subject: subject, # to: invitee.email_address, # from: common_address(inviter), # reply_to: inviter.email_address_with_name # end # # def project_invitation(project, inviter, invitee) # @account = inviter.account # @project = project # @inviter = inviter # @invitee = invitee # @summarizer = ProjectInvitationSummarizer.new(@project.bucket) # # subject = "#{@inviter.name.familiar} added you to a project in Basecamp (#{@account.name})" # # mail \ # subject: subject, # to: invitee.email_address, # from: common_address(inviter), # reply_to: inviter.email_address_with_name # end # # def bulk_project_invitation(projects, inviter, invitee) # @account = inviter.account # @projects = projects.sort_by(&:name) # @inviter = inviter # @invitee = invitee # # subject = "#{@inviter.name.familiar} added you to some new stuff in Basecamp (#{@account.name})" # # mail \ # subject: subject, # to: invitee.email_address, # from: common_address(inviter), # reply_to: inviter.email_address_with_name # end # end # # InvitationsMailer.account_invitation(person_a, person_b).deliver_later # # Using parameterized mailers, this can be rewritten as: # # class InvitationsMailer < ApplicationMailer # before_action { @inviter, @invitee = params[:inviter], params[:invitee] } # before_action { @account = params[:inviter].account } # # default to: -> { @invitee.email_address }, # from: -> { common_address(@inviter) }, # reply_to: -> { @inviter.email_address_with_name } # # def account_invitation # mail subject: "#{@inviter.name} invited you to their Basecamp (#{@account.name})" # end # # def project_invitation # @project = params[:project] # @summarizer = ProjectInvitationSummarizer.new(@project.bucket) # # mail subject: "#{@inviter.name.familiar} added you to a project in Basecamp (#{@account.name})" # end # # def bulk_project_invitation # @projects = params[:projects].sort_by(&:name) # # mail subject: "#{@inviter.name.familiar} added you to some new stuff in Basecamp (#{@account.name})" # end # end # # InvitationsMailer.with(inviter: person_a, invitee: person_b).account_invitation.deliver_later module Parameterized extend ActiveSupport::Concern included do attr_accessor :params end module ClassMethods # Provide the parameters to the mailer in order to use them in the instance methods and callbacks. # # InvitationsMailer.with(inviter: person_a, invitee: person_b).account_invitation.deliver_later # # See Parameterized documentation for full example. def with(params) ActionMailer::Parameterized::Mailer.new(self, params) end end class Mailer # :nodoc: def initialize(mailer, params) @mailer, @params = mailer, params end private def method_missing(method_name, *args) if @mailer.action_methods.include?(method_name.to_s) ActionMailer::Parameterized::MessageDelivery.new(@mailer, method_name, @params, *args) else super end end def respond_to_missing?(method, include_all = false) @mailer.respond_to?(method, include_all) end end class MessageDelivery < ActionMailer::MessageDelivery # :nodoc: def initialize(mailer_class, action, params, *args) super(mailer_class, action, *args) @params = params end private def processed_mailer @processed_mailer ||= @mailer_class.new.tap do |mailer| mailer.params = @params mailer.process @action, *@args end end def enqueue_delivery(delivery_method, options = {}) if processed? super else args = @mailer_class.name, @action.to_s, delivery_method.to_s, @params, *@args ActionMailer::Parameterized::DeliveryJob.set(options).perform_later(*args) end end end class DeliveryJob < ActionMailer::DeliveryJob # :nodoc: def perform(mailer, mail_method, delivery_method, params, *args) mailer.constantize.with(params).public_send(mail_method, *args).send(delivery_method) end end end end