A project lists multiple projects a path elements: <project name="depends_on_many"> ... <repository name="SLE_10"> <path repository="SLE_10" project="dependency_foo"/> <path repository="SLE_10" project="dependency_bar"/> <arch>x86_64</arch> </repository> </project> Now, if I delete dependency_foo, depends_on_many is updated with <project name="depends_on_many"> ... <repository name="SLE_10"> <path repository="standard" project="deleted"/> <path repository="SLE_10" project="dependency_bar"/> <arch>x86_64</arch> </repository> </project> Now, if I delete dependency_bar, the update of depends_on_many is trying to do <project name="depends_on_many"> ... <repository name="SLE_10"> <path repository="standard" project="deleted"/> <path repository="standard" project="deleted"/> <arch>x86_64</arch> </repository> </project> But that gives a DuplicateKey MySQL error since there are two deleted/standard path elements then, so I got around this with: Index: buildservice/src/frontend/app/controllers/source_controller.rb =================================================================== --- buildservice/src/frontend/app/controllers/source_controller.rb (revision 1668) +++ buildservice/src/frontend/app/controllers/source_controller.rb (working copy) @@ -59,8 +59,20 @@ del_repo = DbProject.find_by_name("deleted").repositories[0] lreps.each do |link_rep| pe = link_rep.path_elements.find(:first, :include => ["link"], :conditions => ["db_project_id = ?", pro.id]) - pe.link = del_repo - pe.save + logger.debug "del_repo.id: #{del_repo.id}" + del_pe = link_rep.path_elements.find(:first, :include => ["link"], :conditions => ["db_project_id = ?", del_repo.id]) + logger.debug "del_pe: #{del_pe}" + + # if a dep_repo link already exists, then we can't added another + # one, so just destroy the pe instead of replacing it with deleted + # project + if del_pe.nil? + pe.link = del_repo + pe.save + else + pe.destroy + end + #update backend link_prj = link_rep.db_project logger.info "updating project '#{link_prj.name}'" So, if a deleted/standard is already a path_element, it just deletes the path element instead of replacing it. This should have left depends_on_many like this: <project name="depends_on_many"> ... <repository name="SLE_10"> <path repository="standard" project="deleted"/> <arch>x86_64</arch> </repository> </project> This did not work though, the pe.destroy line caused another DuplicateKey error, this time because 2 path_elements got the same position during the destroy. I traced this to remove_from_list in acts_as_list. The problem is the positions of the lower items are updated before the item being deleted has it's position set to nil. It appears that acts_as_list is written assuming position will not be a unique key. I made this change to get around that position is part of a multicolumn unique key for path_elements: Index: buildservice/src/frontend/vendor/plugins/acts_as_list/lib/active_record/acts/list.rb =================================================================== --- buildservice/src/frontend/vendor/plugins/acts_as_list/lib/active_record/acts/list.rb (revision 1659) +++ buildservice/src/frontend/vendor/plugins/acts_as_list/lib/active_record/acts/list.rb (working copy) @@ -104,7 +104,7 @@ def move_to_bottom return unless in_list? acts_as_list_class.transaction do - decrement_positions_on_lower_items + decrement_positions_on_lower_items(self.send(position_column).to_i) assume_bottom_position end end @@ -122,8 +122,12 @@ # Removes the item from the list. def remove_from_list if in_list? - decrement_positions_on_lower_items + # Set self's position to nil first so duplicate key doesn't happen + # when item directly below self is updated to have same position + # as self. + old_position = self.send(position_column).to_i update_attribute position_column, nil + decrement_positions_on_lower_items(old_position) end end @@ -216,10 +220,9 @@ end # This has the effect of moving all the lower items up one. - def decrement_positions_on_lower_items - return unless in_list? + def decrement_positions_on_lower_items(position) acts_as_list_class.update_all( - "#{position_column} = (#{position_column} - 1)", "#{scope_condition} AND #{position_column} > #{send(position_column).to_i}" + "#{position_column} = (#{position_column} - 1)", "#{scope_condition} AND #{position_column} > #{position}" ) end Now, dependency_bar deletes cleanly. The attached file has both patches. I've sent in patches to this mailing list before and I never know if they get accepted. Can I get some feedback if this is going to be accepted or not or should I be submitting these somewhere else?