What am I doing wrong with GlideDate.subtract()?

[MikeC2278451151]

I am trying to simply get the difference between two times fields and put the duration into a duration field. I figured something simple like this would work:

current.duration = GlideDate.subtract(current.start_time, current.end_time);

But I ended having to write this awful thing to get it to work:

var gd1 = new GlideTime(); 
gd1.setDisplayValue(current.start_time.getDisplayValue()); 
var gd2 = new GlideTime(); 
gd2.setDisplayValue(current.end_time.getDisplayValue()); 
 
current.duration = GlideDate.subtract(gd1 ,gd2);

What am I doing wrong here?

[Bert_c1]

Try the following script logic:

	var testRec = new GlideRecord('u_test_table');
	testRec.query();
	while (testRec.next()) {
		var sDate = new GlideDateTime(testRec.u_start_date);
		var eDate = new GlideDateTime(testRec.u_end_date);
		var sSecs = sDate.getNumericValue() / 1000;
		var eSecs = eDate.getNumericValue() / 1000;
		var diffSecs = eSecs - sSecs;
//		gs.info('Start:' + sDate + ', End: '+ eDate + ', sSecs: ' + sSecs + ', eSecs' + eSecs + ', diff: ' + diffSecs);
		var epochDate = new GlideDateTime("1970-01-01 00:00:00");
		epochDate.addSeconds(diffSecs);
		var dur = new GlideDateTime(epochDate.getValue());
//		gs.info('dur: ' + dur);
		testRec.u_duration = dur;
		testRec.update();
	}

using the info messages I get:

*** Script: Start:2025-03-03 21:34:26, End: 2025-03-05 21:34:26, sSecs: 1741037666, eSecs1741210466, diff: 172800
*** Script: dur: 1970-01-03 00:00:00
*** Script: Start:2025-02-14 15:39:48, End: 2025-02-18 16:40:48, sSecs: 1739547588, eSecs1739896848, diff: 349260
*** Script: dur: 1970-01-05 01:01:00

On the form, we see:

[Brad Bowman · Accepted solution]

To execute methods on the GlideDateTime (GlideDate, GlideTime, whatever) API, you must instantiate the values used in the method also as GlideDateTime (...), so something like this will work:

current.duration = GlideDateTime.subtract(new GlideDateTime(current.start_time), new GlideDateTime(current.end_time));

[MikeC2278451151]

Thank you for the advice. The solution I eventually got to myself was to convert the times to milliseconds, subtract and instantiate a new GlideDuration with that.

	var	Duration = current.end_time.dateNumericValue() - current.start_time.dateNumericValue(); 
	current.duration = new GlideDuration(Duration);

[Ankur Bawiskar]

@MikeC2278451151 

I agree with @Brad Bowman here.

You need to use GlideDateTime object and then use them in subtract method

If my response helped please mark it correct and close the thread so that it benefits future readers.