dates_overdue.rb

class SignificantDates < Job
  def model_name
    'Study'
  end

  def options
    [
      { :name => :valid_submission, :days => 60.days },
      { :name => :kpi_end_date,     :days => 1.month }
    ]
  end

  def condition(study, option)
    date = study.significant_date(option[:name])
    date.present? && date < Time.now - option[:days]
  end

  def action(failures)
    send_email(:to => study.person_with_capacity(:officer), :template => 'alfresco://significant_dates', :failures => failures)    
  end
end

jobs.rake

task :run => [:environment] do
  SignificantDates.run!
  MissingData.run!
end

jobs.rb

class Job < ActiveRecord::Base
  def run!
    failures = []
    model_class.all.each do | record |
      options.each do |option|
        failures << { :record => record, :option => option } unless condition(record, option)
      end
      action(failures) unless failures.empty?
    end
  end

  private

  def options
    []
  end

  def conditions(study, option)
    raise NotImplementedError
  end

  def action(failures)
    raise NotImplementedError
  end

  def model_name
    raise NotImplementedError
  end

  def model_class
    model_name.constantize
  end
end

# We use active record to store when a job is run so we dont over send emails
# and to log any errors. We could even use it to schedule when the job should
# be next run, which can be a different time depending on if an action was
# performed or not.
#
# Omitted: The base class would also rescue any errors and log them

# jobs_table

# type (class of job)
# last_run_at
# error_log
# next_run_at

missing_data.rb

class MissingData < Job
  def model_name
    'Study'
  end

  def options
    [:acrnoymn, :short_title, :ref_code]
  end

  def condition(study, option)
    study.send(option[:field]).blank?
  end

  def action(failures)
    send_email(:to => 'person@example.com', :template => 'alfresco://missing_data', :failures => failures)
  end
end