# File lib/tapkit/access/attribute.rb, line 52
                def validate_required_attributes
                        msg = "Attribute requires attributes: 'name', 'column_name', " +
                                "'external_type', 'class_name'"

                        if @name.nil? or @column_name.nil? or @external_type.nil? or \
                                @class_name.nil? then
                                key = @name || :attribute
                                error = ValidationError.new(msg, key)
                                raise error
                        end
                end