# File lib/tapkit/access/relationship.rb, line 174
                def validate_required_attributes
                        msg = "Relationship requires attributes: 'name', 'destination', " +
                                "'joins' (this requires 'source' and 'destination')"

                        if @name.nil? or @destination.nil? or @joins.empty? then
                                key = @name || :relationship
                                error = ValidationError.new(msg, key)
                                raise error
                        end
                end