How to render text in model

render_to_file.rb

# One thing I don't know is how to pass @var to template.
def to_html
  request = ActionDispatch::Request.new Hash.new
  # I am using Gon also.
  Gon.clear
  Gon::Request.instance_variable_set(:@request_id, request.object_id)
  Gon::Request.env = {}
  # Assign gon variables
  Gon.some_variables = self.some_variables

  view = ActionView::Base.new(views_path)
  view.controller = ArticlesController.new
  view.request = request
  text = view.render(
    :formats => ['json'],
    :template => 'articles/index',
    :layout => 'layouts/application',
    :locals => { :articles => @articles }
  )
end

private

def views_path
  @views_path ||= Rails.configuration.paths["app/views"]
end

def helpers
  @helpers ||= Rails.application.routes.url_helpers
end

def default_host
  @default_host ||= Rails.configuration.action_mailer.default_url_options[:host]
end

zipping.rb

require 'zip/zip'
# Please run the method in background
def generate_offline_zip
  # ensure the folder was there.
  FileUtils.mkdir_p File.join(Rails.root, "tmp", "offline_zips")

  zip_path = File.join(Rails.root, "tmp", "offline_zips", "#{self.id.to_s}.zip")

  # Remove previous generated zip
  FileUtils.rm_rf zip_path

  Zip::ZipFile.open zip_path, Zip::ZipFile::CREATE do |zipfile|
    # Store js css
    zipfile.add "application.js", File.join(Rails.public_path, "assets", "application.js")
    zipfile.add "application.css", File.join(Rails.public_path, "assets", "application.css")
    zipfile.add "your_javascript.js", File.join(Rails.public_path, "assets", "your_javascript.js")
    # Store audio and images
    zipfile.add "audio.mp3", File.join(Rails.public_path, self.audio_path)
    zipfile.add "image.png", File.join(Rails.public_path, "assets", "image.png")
    # Store index.html
    zipfile.get_output_stream("index.html") { |f| f.puts self.to_html }
  end

  # move zip to public folder
  FileUtils.mkdir_p File.join(Rails.public_path, "zips") # make sure folder was there.
  FileUtils.mv zip_path, File.join(Rails.public_path, "zips", "#{self.id}.zip")
  true
rescue => e
  # error processing
  false
end