Sprintf on xml filter xpath

Hi. Is there a way to use sprintf on the xml xpath string? I have to get the node where the value is equal to a field of the event like this but I am getting no results:

	xml {
		source => "[@metadata][body]"
		store_xml => false
		xpath => [ "/test/test1/fieldTable/fieldRow/field/value[text() = '%{[fieldFromEvent]}']/../..", "[@metadata][result]" ]

No, the xml filter just passes the xpath option to Nokogiri, it does not sprintf anything.

Ok thanks. I`ll just use the ruby filter for this.