Delayed_job ActionMailer caching? - ruby-on-rails-3

Question

I currently call a delayed_job (gem delayed_job_mongoid) to send a confirmation email. However, it doesn't seem to use the latest data I'm passing, and instead uses a cached version. See below:
My controller:
...
_user.calculate_orders
_user.save
_user.reload
Mailer.delay.order_reported(_user)
...
The Mailer
class Mailer < Devise::Mailer
def order_reported(to_user)
#to_user = to_user
email_with_name = "#{#to_user.name} <#{#to_user.email}>"
mail(:to => email_with_name, :subject => "Test email")
end
end
For example, if an attribute _user.total_orders = 3 gets updated to 5 and saved. It's correctly reflected in the database, the delayed job DB record contains the updated info of 5, but when email is sent, it uses cached info of 3.
I've also tried calling the method via rails console:
This works and uses the parameter that's passed and updated info
Mailer.order_reported(u).deliver
This doesn't work and uses cached data
Mailer.delay.order_reported(u)

Answer 1

I had a very similar problem with Sidekiq recently, related to passing in a serialized version of my User object instead of just an ID.
I would refactor slightly to only pass simple objects as parameters in the delayed method. So, you could do this instead:
Mailer.delay.order_reported(_user.id)
and then update the method to read as follows:
class Mailer < Devise::Mailer
def order_reported(to_user_id)
#to_user = User.find(to_user_id)
email_with_name = "#{#to_user.name} <#{#to_user.email}>"
mail(:to => email_with_name, :subject => "Test email")
end
end
That would ensure you always get a fresh user object when your mailer is actually delivered.