This method called on a Scope class returns the Hash used for the ActiveRecord .find() call. First it’s a nice way to debug your scopes, second it’s perfect for our need to chain multiple scoped into one. Check this out:

class Fu < ActiveRecord::Base
named_scope :has_moo,  :conditions => { :moo => true }
named_scope :has_foo,  :conditions => { :foo => true }

named_scope :has_moo_and_foo, lambda { has_moo.has_foo.scope(:find) }
end

We chain the two scoped has_moo and has_foo together into a new one called has_moo_and_foo. As the return value can only be a Hash we use the above mentioned scope(:find) to transform it into one.

Now this works:

Fu.has_moo_and_foo.all

Sweet! Imagine how great this would be if we can return a scope object instead of a hash as well??

See my pastie here too.