class ActiveModel::EachValidator

def validate(record)

override +validate_each+ with validation logic.
+validate_each+ to determine validity therefore subclasses should
Performs validation on the supplied record. By default this will call 
def validate(record)
  attributes.each do |attribute|
    value = record.read_attribute_for_validation(attribute)
    next if (value.nil? && options[:allow_nil]) || (value.blank? && options[:allow_blank])
    value = prepare_value_for_validation(value, record, attribute)
    validate_each(record, attribute, value)
  end
end