Java The Hutt

Welcome to installment number 7 of the ruby realities series. Today was a day for nostalgia and made me remember how nice it is to have published and accurate API docs.
Allow me to elaborate. First some code...

class Loan < ActiveRecord::Base
  belongs_to :mailing_address,
             :class_name => "Address",
             :foreign_key => 'mailing_address_id'
  validates_presence_of :mailing_address
 
end
 
class Address < ActiveRecord::Base
 
  def empty?
    (self.line1.nil? || self.line1.empty?) &&
    (self.line2.nil? || self.line2.empty?) &&
    (self.city.nil? || self.city.empty?) &&
    (self.state.nil? || self.state.empty?) &&
    self.zip.nil?
  end
end

What we have here are two active record classes. There's more to them than what's shown here but this is what was needed to reproduce my problem "in the small" as Sam likes to say. Now some more code that demonstrates the problem...

loan = Loan.new
loan.build_mailing_address
loan.valid?
pp loan.errors.inspect

running that code provided me an output of:

@errors={"mailing_address"=>["can't be blank"]}

Huh? but I just created an instance of mailing address. As an experiment I took out the

validates_presence_of :mailing_address

and things were fine. I was able to create my mailing address and have it saved to the database (updating properties on the same related object is another story itself.. one for a later date).

Digging further it turns out that the presence of empty? in Address is causing my validation problem. Renaming it to is_emtpy?, putting my

validates_presence_of :mailing_address

back into the relation fixes the original code above. Obviously I'm using a method name that is already in use but isn't documented anywhere in the rails API. It's not part of ActiveRecord::Base or Object. Nowhere in the :belongs_to API doc does it talk about this method being overridden or used by a proxy, unless I'm missing the warning somewhere. This could very well be user error or a bug and I'm sure to find out soon as I've filed a bug with the RoR team. http://dev.rubyonrails.org/ticket/3646

Sometimes standards and good docs really are your best friends.