Question

I use authlogic for authentication and paperclip for handling user’s profile picture attachments.

I use the following method to get the current_user

    def current_user_session
        return @current_user_session if defined?
(@current_user_session)
        @current_user_session = UserSession.find
    end

def current_user
        return @current_user if defined?(@current_user)
        @current_user = current_user_session &&
current_user_session.record
    end

and the following after_save callback to regenerate the profile image if the image has changed.

   after_save do |user|
        if user.image_changed?
            Delayed::Job.enqueue ImageJob.new(user.id)
        end
    end

The current_user method issues a UserSession.find call and
Looking at the docs it seems UserSession.tries to Log the user
in, which results in an update to certain fields (updated_at, token etc. but not the profile image), which results in a
save of the user record, which in my case results in after_save
callbacks firing. This after save callback checks to see if there has
been a change to user’s profile image, which unnecessarily consumes time.

Now this is fine if the user indeed is trying to
update profile, but since I use current_user in many different places
within my app, this callback is getting fired (and its an expensive
call), for no reason.

I understand this isn’t exactly authlogic issue, but is there anyway I
can avoid this, i.e. either not update the user record or somehow
differentiate between what is a profile update and what is an update
resulting from this UserSession.find login?

Thanks

Here is the solution that worked based on bjg’s suggestion.

before_save :check_what_changed

def check_what_changed
if self.changed.sort == [“last_request_at”, “perishable_token”]
self.skip_profile_update = true
return true
else
self.skip_profile_update = false
return true
end
end

Update #2
I take that back that didn’t work, but it’s not really a problem with this solution, for some reason paperclip tries to save the attachments even before the after_save callback. This is likely a paperclip issue, no idea..

Answer 1

In a before_save callback, you could differentiate between a real profile change and the Authlogic related changes (last_request_at and updated_at attributes) using the Rails built-in dirty objects tracking facility. Something along these lines

attr_accessor :skip_profile_update

before_save do |model|
  model.skip_profile_update = (model.changed.sort == ['last_request_at', 'updated_at'])
end

after_save do |model|
  unless model.skip_profile_update
    # etc
  end
end