How to remove validation using instance_eval clause in Rails?

Question

I would like to enhance existing class using instance_eval. There original definition contains validation, which require presence of certain fields, ie:

class Du         


        

Answer 1

If you can edit the constraint on the original model to put an :if => :some_function on it, you can easily change the behavior of the function it calls to return false. I tested this and it works pretty easily:

class Foo < ActiveRecord::Base

  validates :field, :presence => true, :if => :stuff


  attr_accessor :field

  def stuff
      return true;
  end

end

and then somewhere else:

Foo.class_eval {
  def stuff
    false
  end
}