validate_on_destroy ?

What's the best way to validate_on_destroy. Rails only seems to include
validate_on_create and validate_on_update methods. I don't want to
resort to doing:
before_destroy do |j|
raise "There is an error" if j.etc
end
Is there a way of finding out what action (create/update/destroy) is
being performed if I use the 'validate' method?

The best approach is to use callbacks:

  class Model < ActiveRecord::Base
    before_destroy :on_destroy_validation_method
  end

This is usually useful to clean assocciated data or something like that.