Question

I was learning some Rspec stuff and accidentally introduced some code into my model class which I expected to create an error. But to my surprise there were non.

class Address < ActiveRecord::Base
  attr_accessible :city, :country, :person_id, :street, :zip
  validates_presence_of :city, :zip, :street
  before_save :setDefaultCountry

  # -- Beginning strange code --

  if true
     puts "Hey! I shouldn't be able to do this"
  end       

  # -- End of strange code --

  private   
  def setDefaultCountry
    if self.country.blank?
      self.country = "US"
    end
  end
end

This is the rails console output:

Arman$ rails console
Loading development environment (Rails 3.2.3)
1.9.3p194 :001 > a = Address.new
Hey! I shouldn't be able to do this
 => #<Address id: nil, street: nil, city: nil, zip: nil, country: nil, person_id: nil, created_at: nil, updated_at: nil> 
1.9.3p194 :002 > 

Why isn’t ruby complaining about strange code being added inside the class definition?

Answer 1

That’s just how ruby works. You don’t think that attr_accessible should cause error, do you? But this is just a regular method call! Here’s its source

# File activerecord/lib/active_record/base.rb, line 1083
def attr_accessible(*attributes)
  write_inheritable_attribute(:attr_accessible, 
                              Set.new(attributes.map(&:to_s)) + (accessible_attributes || []))
end

You can run arbitrary ruby code in the class definition. This is a feature, not a bug 🙂