Conditional Validations in Rails

August 28, 2007

The single table inheritance feature of rails is really useful. Today I needed to turn off validations in the extended model that were implemented in the base class.

I scratched my head for a while then realised its actually very simple.

  
  class Page < ActiveRecord::Base
  
  validates_presence_of :title, :slug, 
      :description, :if => :is_a_page?
  
  private
  
  def is_a_page?
    self.class == 'Page'
  end
  
  end

The above validation only takes place for the base class and not for classes that extend this. The beauty of STI being that the database stays pretty clean.