How should my Rails before_validation callbacks handle bad data?
class Foo < ActiveRecord::Base

  before_validation :capitalize_title
  validates :title, :presence => true

  def capitalize_title
    title.upcase
  end

end

def capitalize_title
  title = title.upcase if title
end

before_validation :mangle_data
validate :data_is_okay

#...

def mangle_data
    return if(!data_is_mangleable)
    #... mangle away
end

def date_is_okay
    if(!data_is_mangleable)
        # complain
    end
    if(!data_is_properly_mangled)
        # complain some more
    end
end

def data_is_mangleable
   return false if(thing.nil?)
   # etc.
end

def data_is_properly_mangled
   # check that stuff that the before_validation hook doesn't
   # have to care about.
end