January 23rd, 2007
Delegate is a pretty sweet method. Have you used it yet? Let’s say you have:
class User < ActiveRecord::Base
has_many :actions
end
class Action < ActiveRecord::Base
belongs_to :user
class << self
def inbox
find(:all, :conditions => ['inbox = 1'])
end
end
endTo access a users inbox actions you would have to:
user = User.find(1)
user.actions.inboxThis isn’t bad, but let’s throw delegate into the mix like so:
class User < ActiveRecord::Base
has_many :actions
delegate :inbox, :to => :actions
end
class Action < ActiveRecord::Base
belongs_to :user
class << self
def inbox
find(:all, :conditions => ['inbox = 1'])
end
end
endNow you can access a user’s inbox actions like this:
user = User.find(1)
user.inbox # instead of user.actions.inboxJust like the title of this article, the User model says I don’t feel like dealing with the inbox method so why don’t you deal with it Action. Saves some keystrokes and it just feels right.
Jan 25, 2007
Nice. Delegate looks to be very useful. Thanks for the tip!
Jan 27, 2007
so,
class klass delegate :inbox, :to => :actions end
means; klass.actions.inbox ??
why :through doesn’t work here?
Jan 29, 2007
It should be pointed out that this doesn’t work on Ruby 1.8.2. All the more reason for folks to update to 1.8.5.
Jan 30, 2007
@inanc – :through is for join models. Inbox is not a model. It is a class method in Action. It doesn’t join to models together. Rather, it just forwards a method call to another class.
@Danger – Thanks for pointing that out.
Feb 20, 2007
http://quotedprintable.com/2006/12/22/delegation-and-demeter-in-rails ... is the correct url for “Delegation and Demeter in Rails”