Question

The following scope definition contains two bugs, which causes it not to work as expected. Can you find them?

named_scope :articles_to_display, 
            :conditions => ["articles.publish_at < (?)", Time.now]

(the column publish_at contains time/date, when the article should be published). The bugs are fundamental ones, not just a typos.

I will either accept the first correct answer or post the solution in few days.

Answer 1

The first problems is that Time.now is evaluated at the class level (when the file is read by Ruby) and not evaluated when the scope is used (which is what you most likely expect). In that case you need to wrap the conditions generation in a lambda/proc.

named_scope :articles_to_display, lambda { 
   :conditions => ["articles.publish_at < (?)", Time.now]
}

The second issue is likely that you’re want to use Time.zone.now instead of Time.now to respect the localized time of the current request rather than the system time on the server.

The following is what you want to end up with:

named_scope :articles_to_display, lambda { 
   :conditions => ["articles.publish_at < (?)", Time.zone.now]
}