在涉及数据库访问的Rails上调度ruby

Question

I want to schedule daily reports to subscribed users via email.
For that I have written action in reports_controller that fetch data from database & convert it into pdf using pdfkit/wkhtmltopdf.
The action works fine when called from get request.But when converted so that be defined like

def self.dailymail
   ac = ActionController::Base.new()
   kit = PDFKit.new        #retrieve data from db  
   pdf = kit.to_pdf
   ReportMailer.send_reports(ac.send_data(pdf)).deliver
 end

It raises exception at send_data call when used with rufus scheduler:

RackDelegation#content_type= delegated to @_response.content_type=, but @_response is nil: #<ActionController::Base:0x206b068 @_routes=nil, @_action_has_layout=true, @_headers={"Content-Type"=>"text/html"}, ...

so, my question is what how can I solve this problem or Is there any alternate scheduler in rails that work fair on both Windows and Linux?
I wish to know any scheduler that can be helpful to send reports fetched from database.

Answer 1

As willglynn already points out, you should get rid of any controller interaction. There's simply no need here and it makes things unnecessarily complicated. So your code should look more like

def self.dailymail
   kit = PDFKit.new        #retrieve data from db  
   pdf = kit.to_pdf
   ReportMailer.send_reports(pdf).deliver
end

If you got problems with the rufus scheduler (which I don't know), you could create a rake task to send out your mails and use the OS scheduler (eg cron on Linux) to call the task. Having the rake task would be also convenient for testing.

Answer 2

I agree with claasz regarding the rake task. Check out the whenever gem https://github.com/javan/whenever There is no suport for windows Task Scheduler, but it does support creating cron jobs.

Check out the documentation for the details, but esentially the gem creates cron jobs based on what you configure in the schedule.rb file that is created when you install the gem.

sample content of schedule.rb:

every 3.hours do
  runner "MyModel.some_process"
  rake "my:rake:task"
  command "/usr/bin/my_great_command"
end

This would be like running bundle exec rake my:rake:task every 3 hours

After creating the schedule.rb you will need to run the whenever command from the console in order to add your schedule to cron. If you run whenever without arguments, the output shows you the contents of the schedule.rb. There is an argument you need to provide that I can't remember off the top of my head, just pass --help and I think you'll get the answer.

Hope this helps

EDIT:The argument is -w to write to cron-tab