name_exists?

# File activerecord/examples/validation.rb, line 25
  def self.name_exists?(name, id = nil)
    if id.nil?
      condition = [ "name = '%s'", name ]
    else
      # Check if anyone else than the person identified by person_id has that user_name
      condition = [ "name = '%s' AND id <> %d", name, id ]
    end

    !find_first(condition).nil?
  end