+ def create_with_history(user)
+ check_create_element_consistency(self, user)
+ raise OSM::APIPreconditionFailedError, "Cannot create way: data is invalid." unless preconditions_ok?
+
+ self.version = 0
+ self.visible = true
+ save_with_history!
+ end
+
+ def preconditions_ok?(old_nodes = [])
+ return false if nds.empty?
+ raise OSM::APITooManyWayNodesError.new(id, nds.length, Settings.max_number_of_way_nodes) if nds.length > Settings.max_number_of_way_nodes
+
+ # check only the new nodes, for efficiency - old nodes having been checked last time and can't
+ # be deleted when they're in-use.
+ new_nds = (nds - old_nodes).sort.uniq
+
+ unless new_nds.empty?
+ # NOTE: nodes are locked here to ensure they can't be deleted before
+ # the current transaction commits.
+ db_nds = Node.where(:id => new_nds, :visible => true).lock("for share")
+
+ if db_nds.length < new_nds.length
+ missing = new_nds - db_nds.collect(&:id)
+ raise OSM::APIPreconditionFailedError, "Way #{id} requires the nodes with id in (#{missing.join(',')}), which either do not exist, or are not visible."
+ end