Rendering views in rake tasks

Posted by: Jake Dempsey on: May 23, 2009

• In: Ruby | Ruby on Rails
• Comment!

Recently, I needed to create a background process to offload a long export process. The easiest approach was to just utilize a rake task that would be kicked off by the system command. I ran into an issue because I needed to capture the rendering of a view to create the export file. This is an example of the code that came out of the exploration:

  task :run_export => :environment do
    av = ActionView::Base.new(Rails::Configuration.new.view_path)
    av.class_eval do
      include ApplicationHelper
    end
 
    chars = ("a".."z").to_a + ("A".."Z").to_a + ("0".."9").to_a
    file_name = "export_"
    10.times { file_name << chars[rand(chars.size-1)] }

    data = av.render(:partial => "shared/export", :locals => {:surveys => Survey.all})
    FileUtils.mkdir_p "#{RAILS_ROOT}/public/system/exports}"
    File.open("#{RAILS_ROOT}/public/system/exports/#{file_name}.xls", 'w') {|f| f.write(data) }
  end

The above rake task will create an instance of ActionView so that we can call render. My partial also needed access to some helpers I have defined in my ApplicationHelper, so it gets included. Next we generate a psuedo random file name for our export. Then we create a directory for our export files. The directory and its parents are only created if they do not exist. Lastly, we write the result of our render to our file.

Not sure if this is the best approach to this..but seems to work for me.