+ end
+
+ def create_with_history(user)
+ check_create_consistency(self, user)
+ unless self.preconditions_ok?
+ raise OSM::APIPreconditionFailedError.new("Cannot create way: data is invalid.")
+ end
+ self.version = 0
+ self.visible = true
+ save_with_history!
+ end
+
+ def preconditions_ok?(old_nodes = [])
+ return false if self.nds.empty?
+ if self.nds.length > MAX_NUMBER_OF_WAY_NODES
+ raise OSM::APITooManyWayNodesError.new(self.id, self.nds.length, MAX_NUMBER_OF_WAY_NODES)
+ end
+
+ # 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 = (self.nds - old_nodes).sort.uniq
+
+ unless new_nds.empty?
+ db_nds = Node.where(:id => new_nds, :visible => true)
+
+ if db_nds.length < new_nds.length
+ missing = new_nds - db_nds.collect { |n| n.id }
+ raise OSM::APIPreconditionFailedError.new("Way #{self.id} requires the nodes with id in (#{missing.join(',')}), which either do not exist, or are not visible.")
+ end
+ end
+
+ return true
+ end