I have several ActiveResource model in my project. There was so strange to me when I called to_xml on my ActiveResource. The options that I passed to to_xml like :only and :except doesn''t work at all. On ActiveRecord, it works really well. Anyone knows? class Node < ActiveResource::Base self.site = NODE_SERVER end # node has uuid, name, type attributes node = Node.find("3333") node.to_xml(:only => [:uuid]) # after here, i still get all attributes <?xml version=\"1.0\" encoding=\"UTF-8\"?>\n<node>\n <uuid type\"integer\">0</uuid>\n <name>AAAA</name>\n <type></type>\n</node>