module ActiveRecord
  module Validations
    def self.append_features(base) #:nodoc:
      super
      base.extend ClassMethods
    end

  module ClassMethods
   # Automatically defines length limits for columns that have such limits in the DB
   def columns_with_limit
     return @limit_columns if @limit_columns
     @limit_columns = []
     begin
       content_columns.find_all { |col| col.type == :string and col.limit }.each do |col|
        @limit_columns << [col.name, col.limit]
       end if content_columns
      return @limit_columns
     end
     return []
   end

   # Automatically defines validate_presence_of for DB columns with NOT NULL and no default
   def mandatory_content_columns
    return @mandatory_content_columns if @mandatory_content_columns
    @mandatory_content_columns = []
    begin
      content_columns.find_all { |col| !col.null and col.default.nil? }.each do |col|
        @mandatory_content_columns << col.name
      end if content_columns
      return @mandatory_content_columns
    end
    return []
  end

 end
end