+ def assign_generic_name_if_none_given
+ if new_record? and link_class == 'name' and (!name or name.empty?)
+ # Creating a name link with no name means "invent a generic
+ # name, like New Foo (1)"
+
+ head_class = ArvadosModel::resource_class_for_uuid(head_uuid)
+ if !head_class
+ errors.add :name, 'cannot be automatically assigned for this uuid'
+ return
+ end
+ name_base = "New " + head_class.to_s.underscore.humanize.downcase
+ if not Link.where(link_class: link_class,
+ tail_uuid: tail_uuid,
+ name: name_base).any?
+ self.name = name_base
+ else
+ # Find how many digits the largest N has among "New model (N)" names
+ maxlen = ActiveRecord::Base.connection.
+ execute("SELECT max(length(name)) maxlen FROM links "\
+ "WHERE link_class='name' "\
+ "AND tail_uuid=#{Link.sanitize(tail_uuid)} "\
+ "AND name~#{Link.sanitize "#{name_base} \\([0-9]+\\)"}")[0]
+ if maxlen and maxlen['maxlen']
+ # Find the largest N by sorting alphanumerically
+ maxname = ActiveRecord::Base.connection.
+ execute("SELECT max(name) maxname FROM links "\
+ "WHERE link_class='name' "\
+ "AND tail_uuid=#{Link.sanitize(tail_uuid)} "\
+ "AND length(name)=#{maxlen['maxlen']} "\
+ "AND name~#{Link.sanitize "#{name_base} \\([0-9]+\\)"}"
+ )[0]['maxname']
+ n = maxname.match(/\(([0-9]+)\)$/)[1].to_i
+ n += 1
+ else
+ # "New foo" is taken, but "New foo (1)" isn't.
+ n = 1
+ end
+ self.name = name_base + " (#{n})"
+ end
+ end
+ end
+