如何通过Rails上的用户交互在heroku上运行“ cron脚本”？

Question

I have the following script which runs once a day on cron on heroku.

However, I realize that I would like the option for the user to be able to press a button from a web page to initiate this same process.

Is there a way to create a 'subroutine' that either cron can call or from a web request? I don't want to use a separate service that runs jobs.

I've just put a snippet to illustrate.....

letter_todos = Todo.current_date_lte(Date.today).asset_is("Letter").done_date_null

  unless letter_todos.blank? #check if there any ToDos

   # group by asset_id so that each batch is specific to the asset_id
   letter_todos.group_by(&:asset_id).each do |asset_id, letter_todos|
   #  pdf = Prawn::Document.new(:margin => 100) #format the PDF document
       html_file = ''
       letter_todos.each do |todo| #loop through all Letter_Todos

         contact = Contact.find(todo.contact_id) #get associated contact
         letter = Letter.find(todo.asset_id) #get associated Letter 

         redcloth_contact_letter = RedCloth.new(letter.substituted_message(contact, [])).to_html

         html_file = html_file + redcloth_contact_letter
         html_file = html_file + "<p style='display: none; page-break-after: always'><center> ... </center> </p>"

       end 

       kit = PDFKit.new(html_file)
       kit.stylesheets << "#{RAILS_ROOT}/public/stylesheets/compiled/pdf.css" 
       file = kit.to_pdf

       letter = Letter.find(asset_id)
       #OutboundMailer.deliver_pdf_email(file)
       kit.to_file("#{RAILS_ROOT}/tmp/PDF-#{letter.title}-#{Date.today}.pdf")

       # Create new BatchPrint record

       batch = BatchPrint.new
       batch.pdf = File.new("#{RAILS_ROOT}/tmp/PDF-#{letter.title}-#{Date.today}.pdf")

Answer 1

I've done this by putting the function in question in a file in lib (lib/tasks_n_stuff.rb, say):

module TasksNStuff
    def self.do_something
        # ...doing something...
    end
end

Then I can call if from a Rake task:

desc 'Make sure we depend on :environment, so we can get to the Railsy stuff...'
task :do_something => :environment do
    TasksNStuff.do_something
end

Or from a controller (or anywhere, really):

class WhateverController < ApplicationController
    def do_something
        TasksNStuff.do_something
    end
end

And since you can run a rake task as a cron job ( cd /my/rails/root; rake do_something ), that should be all you need. Cheers!