Rails中DateTime.now.strftime（'Y％m％d％H％M％S'）正确的字符串格式

Question

I'm trying to build a reference number for booking in Rails. I'm using

DateTime.now.strftime('Y%m%d%H%M%S')

for the reference number and concatenate some string. I used Sidekiq for performing this as a background job but then was confused with the result because it gave a different value in strftime .

def to_reserve
   venue = Venue.find(params[:id])
   venue_name = venue.name.delete(' ')
   reference_number = ReferencesNumberWorker.perform_in(5.seconds,    venue_name) 

   ................

end

Sidekiq:

class ReferencesNumberWorker
    include Sidekiq::Worker

    def perform(venue_name)
        reference_number = DateTime.now.strftime('Y%m%d%H%M%S')
        return venue_name + reference_number
    end
end

This is a sample result:

HotelMatt67fb02cb5da7871f92347df9

which I didn't expect with the right result.

Answer 1

That's appending the hash for a Sidekiq job to your reference number where you are expecting it to append the return of the Sidekiq result.

So essentially this method

def to_reserve
   venue = Venue.find(params[:id])
   venue_name = venue.name.delete(' ')
   reference_number = ReferencesNumberWorker.perform_in(5.seconds,    venue_name)  <- This line will return Sidekiq job number, not the actual result from Sidekiq perform operation. 

   ................

end

When you define reference number you're assuming it'll give you the Sidekiq return, which it won't. This is the fundamental point of background jobs. You're disconnecting the Sidekiq job from what you're doing, ie offloading to a separate process. So you can't expect a return, you're offloading the method to Sidekiq. Sidekiq's return is basically the job number.

If you want this to work then move the reference number computation that you're doing to Sidekiq in the to_reserve method OR if it must be done in Sidekiq move all of the logic from to_reserve to Sidekiq's perform method.

Also note, to use Sidekiq you should pass (to Sidekiq) the object's id so you can relook it up in Sidekiq and perform some idempotent operation on the object. In my opinion, I don't think in this case you need to use Sidekiq. Its unnecessary complexity, but to each their own.

Sidenote: Prefer the Time class ( Time#now vs. DateTime#now ) over DateTime to compute the strftime method. Its a pure Ruby method and is faster than the DateTime class (a known performance bottleneck). Also your code won't have a hard dependency on Rails.