Rails - Whenever gem - Dynamic values

Question

Lets say I have a cronjob like this:

every 1.day, :at => '4:30 am' do  
  runner "MyModel.task_to_run_at_four_thirty_in_the_morning"  
end  

Although, I would like to make '1.day' more dynamic, such as changing the value via a form in an administration page.

Then it could look like this:

every Constant.find(2).value, :at => '4:30 am' do 

or

@const = Constant.find(2)
every @const.span, :at => @const.time do 

Can anyone come up with an idea on how to make this work?

Obviously, the reason for this would be that I could use the values stored in the database on my site, like an message saying

<%= "The next update is in less than #{@const.time}" #or something similar %>

Shorthorn

Answer 1

I've never tried, but you should be able to do this by loading up the Rails environment in whenever so that you can use your model classes. Just use require File.dirname(__FILE__) + "./environment" (or "./application" for Rails 3) in your schedule.rb, assuming your schedule.rb is in the config dir.

However, since all whenever does is generate lines in the crontab, any changes made to any Constant would require running whenever --update-crontab again.

Breast

Answer 2

Thank you idlefingers! It totally worked. Here's my solution:

require "#{RAILS_ROOT}/config/environment.rb"

@notification_daily = Constant.find_by_key("notification_daily_time_span")
every eval(@notification_daily.value), :at => @notification_daily.additional_data do
  runner "Notification.daily"
end

@notification_weekly = Constant.find_by_key("notification_weekly_time_span")
every eval(@notification_weekly.value), :at => @notification_weekly.additional_data do
  runner "Notification.weekly"
end

.value can contain for example: 1.day or :sunday
.additional_data contains the timestamp, example: 11:00am

And yes, I'm aware that I need to run --update crontab again :)
But I'll let a cronjob update itself, hehe.

Shorthorn

That doesn't work for me in Rails4. The require statement doesn't work. any idea what do I need to change? – Sutler

I haven't tried Rails 4 myself yet, but i think RAILS_ROOT is changed to Rails.root. – Shorthorn

@Shorthorn : What is this line means, can you help me to get rid of it. notification_weekly = Constant.find_by_key("notification_weekly_time_span") - also what is notification_weekly_time_span – Leonerd

@Leonerd That is just my own model which I can change via my Admin UI. It's a model that has value and additional_data to be able to generate a Whenever row dynamically. You can fetch any data you want, as long as its value translates to any valid Whenever value. As stated in my answer: .value can contain for example: 1.day or :sunday .additional_data contains the timestamp, example: 11:00am – Shorthorn

@Shorthorn Thanks for the information. but I am still confused how to achieve this one. can you help me? can you share your code or can you list steps? – Leonerd

If you read my question, the only thing I am doing is replaceing 1.day and 4:30 am inside every 1.day, :at => '4:30 am' do with variables from my application. Only difference is, that 1.day is a string (from @notification_daily.value), so it need an eval() around it. – Shorthorn

Thank you for your answer! Can you tell, please , what about "cronjob update itself"? How you finally achieve autoupdating? – Will

Just create a normal cron job, that runs something like cd your/app && bundle exec whenever --update-crontab – Shorthorn

Answer 3

# In rails 4
require File.expand_path('../..//config/environment.rb', __FILE__)

# This is your table by which you will get your new value 
bid_update = DynamicOfferTime.first

# Now Task As
every (bid_update.hour_value).hours do
  puts "This will repeat in every #{bid_update.hour_value} hour"
end

Do not forget to update whenever

Archery

I use rails 4 too, require "#{RAILS_ROOT}/config/environment.rb" works fine here. – Shorthorn

Thanks, But I faced this issue and resolved by above. – Archery

Answer 4

I had the same task and decided to solve it a bit another approach. In my table have a lot of records where storing settings for schedule (daily, monthly, weekly, time)

In schedule.rb file I added a cron job, which was running every day at 00:00 and select the records, which can be run today. And after it added to queue with sidekiq using perform_at.

Bimetallism