Generate Email Body from Controller or Observer to Send via Delayed Job

abstract_email_controller.rb

# controllers/shared/abstract_email_controller.rb
module Shared
  
  class AbstractEmailController < AbstractController::Base

    include AbstractController::Rendering
    include AbstractController::Layouts
    include AbstractController::Helpers
    include AbstractController::Translation
    include AbstractController::AssetPaths
    include Rails.application.routes.url_helpers
    include ActionView::Helpers::AssetTagHelper

    # Uncomment if you want to use helpers 
    # defined in ApplicationHelper in your views
    # helper ApplicationHelper

    # Make sure your controller can find views
    self.view_paths = "app/views"
    self.assets_dir = '/app/public'

    # You can define custom helper methods to be used in views here
    # helper_method :current_admin
    # def current_admin; nil; end

    def generate_notification_email(post, host = ENV['RAILS_SERVER'])
      render :partial => "posts/notification_email", :locals => { :post => post, :host => host }
    end

  end

end

notification_email.html.erb

<%# views/posts/notification_email.html.erb %>

Hey <%= post.user.name %>,

Just letting you know that your post was created swimmingly.

<%= post_path(post) %>

-love,

team

post_notification_mail.rb

# mailers/post_notification_mail.rb
class PostNotificationMail < ActionMailer::Base

  def send_notification(post_id, body)
    post = Post.find(post_id)
    sender = "[email protected]"
    recipient = post.user.email
    mail(:content_type => "text/html", :from => sender, :to => recipient, :subject => "We've Got Goodies for You!", :body => body )
  end

end

post_observer.rb

# observers/post_observer.rb
#
# Don't forget to load this in application.rb
#
class PostObserver < ActiveRecord::Observer

  def after_create(post)
     email_body = Shared::AbstractEmailController.new.generate_notification_email(post)
     PostNotificationMail.delay.send_notification(post.id, email_body)
  end

end