+ TYPES = %w[node way relation].freeze
+
+ def self.from_xml(xml, create = false)
+ p = XML::Parser.string(xml, :options => XML::Parser::Options::NOERROR)
+ doc = p.parse
+
+ doc.find("//osm/relation").each do |pt|
+ return Relation.from_xml_node(pt, create)
+ end
+ raise OSM::APIBadXMLError.new("node", xml, "XML doesn't contain an osm/relation element.")
+ rescue LibXML::XML::Error, ArgumentError => e
+ raise OSM::APIBadXMLError.new("relation", xml, e.message)
+ end
+
+ def self.from_xml_node(pt, create = false)
+ relation = Relation.new
+
+ raise OSM::APIBadXMLError.new("relation", pt, "Version is required when updating") unless create || !pt["version"].nil?
+
+ relation.version = pt["version"]
+ raise OSM::APIBadXMLError.new("relation", pt, "Changeset id is missing") if pt["changeset"].nil?
+
+ relation.changeset_id = pt["changeset"]
+
+ unless create
+ raise OSM::APIBadXMLError.new("relation", pt, "ID is required when updating") if pt["id"].nil?
+
+ relation.id = pt["id"].to_i
+ # .to_i will return 0 if there is no number that can be parsed.
+ # We want to make sure that there is no id with zero anyway
+ raise OSM::APIBadUserInput, "ID of relation cannot be zero when updating." if relation.id.zero?
+ end
+
+ # We don't care about the timestamp nor the visibility as these are either
+ # set explicitly or implicit in the action. The visibility is set to true,
+ # and manually set to false before the actual delete.
+ relation.visible = true
+
+ # Start with no tags
+ relation.tags = {}
+
+ # Add in any tags from the XML
+ pt.find("tag").each do |tag|
+ raise OSM::APIBadXMLError.new("relation", pt, "tag is missing key") if tag["k"].nil?
+ raise OSM::APIBadXMLError.new("relation", pt, "tag is missing value") if tag["v"].nil?
+
+ relation.add_tag_keyval(tag["k"], tag["v"])
+ end
+
+ # need to initialise the relation members array explicitly, as if this
+ # isn't done for a new relation then @members attribute will be nil,
+ # and the members will be loaded from the database instead of being
+ # empty, as intended.
+ relation.members = []
+
+ pt.find("member").each do |member|
+ # member_type =
+ raise OSM::APIBadXMLError.new("relation", pt, "The #{member['type']} is not allowed only, #{TYPES.inspect} allowed") unless TYPES.include? member["type"]
+
+ # member_ref = member['ref']
+ # member_role
+ member["role"] ||= "" # Allow the upload to not include this, in which case we default to an empty string.
+ relation.add_member(member["type"].classify, member["ref"], member["role"])