What happens when I’m bored:
david@david-laptop:~/code$ irb irb(main):001:0> class Integer irb(main):002:1> def inspect irb(main):003:2> if self == 42 irb(main):004:3> "The answer to life, the universe, and everything" irb(main):005:3> else irb(main):006:3* super irb(main):007:3> end irb(main):008:2> end irb(main):009:1> end => nil irb(main):010:0> 42 => The answer to life, the universe, and everything
I don’t have time to post links neither Saturday, nor Sunday. So I’m posting them now.
Funny Simpsons quote from an episode I watched yesterday: Bart meats a bunch of robots. “Hi, we’re abandoned robots too.” “I am not a robot, I’m a human!” “Ooh, how is it to feel?” “I said I’m a human, not a girl.”
This is really old news but I’m aiming to have one post per open source project on this blog.
Virtual Attribute Cache is the ultimate way to cache Active Record virtual attributes. The idea is simple. Say, for example, you have a first_name and a last_name column. Then you might have a full_name virtual attribute that joins first_name and last_name plus a full_name column in your database which stores the cached value of the full_name virtual attribute. With va_cache that would be accomplished like this:
class Person < ActiveRecord::Base
cached_virtual_attribute(:full_name, :expire_if => Proc.new { |p| p.first_name_changed? || p.last_name_changed? }) do
[first_name, last_name].join(' ')
end
end
Basically, you need to provide va_cache with three things:
Proc will be evaluated in a before_save callback.)If you don’t like to have Proc’s in the middle of your method calls you can use this alternative syntax:
class Person < ActiveRecord::Base
cached_virtual_attribute :full_name, :expire_if => :first_name_or_last_name_changed do
[first_name, last_name].join(' ')
end
def first_name_or_last_name_changed?
first_name_changed? || last_name_changed?
end
end
Final notes:
va_cache with simple stuff like full names, obviously.:expire_if a question mark will be appended automatically.That’s it. Enjoy!
It’s been quiet the last couple of days…