-
- # pre-set all the old nodes to OK, as we must have checked them before.
- checked = old_nodes.inject(Hash.new) {|h,n| h[n] = true; h }
-
- self.nds.each do |n|
- unless checked.key? n
- node = Node.find(:first, :conditions => ["id = ?", n])
- unless node and node.visible
- raise OSM::APIPreconditionFailedError.new("Way #{self.id} requires the node with id #{n}, which either does not exist, or is not visible.")
- end
- checked[n] = true
+
+ # 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.")