XPath to find elements based on time values

Question

I have the following XML, returned from a web service (5 extra points for guessing the movie):

<ArrayOfSub xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns="http://tempuri.org/"&gt;
  <Sub>
    <SubId>862</SubId>
    <SubStreamId>1</SubStreamId>
    <SubTimeStart>00:01:04.4450000</SubTimeStart>
    <SubTimeEnd>00:01:08.2450000</SubTimeEnd>
    <SubText>Wikus van de Merwe
MNU Alien Affairs

    </SubText>
  </Sub>
  <Sub>
    <SubId>863</SubId>
    <SubStreamId>1</SubStreamId>
    <SubTimeStart>00:02:11.3430000</SubTimeStart>
    <SubTimeEnd>00:02:14.8430000</SubTimeEnd>
    <SubText>Sarah Livingstone
Sociologist, Kempton Park University

    </SubText>
  </Sub>
</ArrayOfSub>

I need the <SubText> element for all elements meeting the following conditions:

SubTimeStart < now && SubTimeEnd > now

I'm doing this in Javascript, for a WebOs app on the Palm Pre. I'm not sure exactly what resolution would be appropriate for my prototype.js PeriodicExecuter, but 1/100th of a second seems to be working OK.

What XPath query will return the element representing what's supposed to be on the screen right now?

Answer 1

XPath does have some date handling functions - though there doesn't seem to be any mention of milliseconds in that list.

I guess the query would be something like this:

nowH = 0;
nowM = 2;
nowS = 26;

/ArrayOfSub/sub     //linebreaks added for readability
    [fn:hours-from-time(SubTimeStart) <= nowH]
    [fn:minutes-from-time(SubTimeStart) <= nowM]
    [fn:seconds-from-time(SubTimeStart) <= nowS]
    [fn:hours-from-time(SubTimeEnd) >= nowH]
    [fn:minutes-from-time(SubTimeEnd) >= nowM]
    [fn:seconds-from-time(SubTimeEnd) >= nowS]
    /SubText

Answer 2

Try this:

var district = 9; // hint

var now = "00:00:00.123"; // manual format is an option?
var xpath = "/ArrayOfSub/Sub["+
    " SubTimeStart <= " + now + " and " +
    " SubTimeEnd   >= " + now + "]/SubText"
 

Answer 3

XPath2 supports dates and times, so if WebOs uses XPath2 you can do something simple like:

//Sub[(SubStartTime < '00:02:13.243') and SubEndTime > '00:02:13.243']

otherwise you can convert the time to a simple integer like so:

//Sub[
  (concat(substring(SubTimeStart,1,2), substring(SubTimeStart,4,2), substring(SubTimeStart,7)) < '000213.243')
and
  (concat(substring(SubTimeEnd,1,2), substring(SubTimeEnd,4,2), substring(SubTimeEnd,7)) > '000213.243')
]

These queries should select the second item.