Subtract time from duration

[palmen]

I've got a duration field and wan't to substract a specified time from this duration. How do I do this in a Business Rule?

I've got it to work when trying to add the time, but not when subtracting.

This is the code I'm working with at the moment.

calendar_duration is the OOTB field on incident

u_correction_time is a glide_time field

(function executeRule(current, previous /*null when async*/) {
   //Get the Duration
   var dur = new GlideDuration();
   dur.setValue(current.calendar_duration);
   gs.log('DURATION: ' + dur);
   //Get the Correction time and calculate adjusted duration
   var corr = new GlideDuration();
   corr.setValue(current.u_correction_time);
   gs.log('CORRECTION: ' + corr);
   dur.subtract(corr);
   //Set Adjusted Duration to dur variable
   current.u_adjusted_duration = dur;
})(current, previous);

The adjusted duration is wrong with 1h as you can see here, the Adjusted Duration should have been 2 hours in this case

[palmen]

The issue is that the correction time in the example is 4 hours, but the value I get is 3h stored in the corr variable.

How can I get the correct value stored in corr?

It always subtract 1h from the time shown on the form, therefore I get the adjusted duration calculated wrong.

The value stored in the corr variable adjust to my timezone. If I change the timezone to be GMT+2 it removed 2h from the value in "Correction time" field

[Abhinay Erra]

What does the log show? Does it show correct value?

[palmen]

The log for corr variable showed 1h less compared to the form.

This was du to timezone since my user is in CET timezone and not in GMT.

I should have fixed it now with the post I marked as correct

[palmen · Accepted solution]

Think I've solved it now, had to add/remove the offset for the user compared to GMT to get the correct values

(function executeRule(current, previous /*null when async*/) {

   //Get the Duration
   var dur = new GlideDateTime(current.calendar_duration);

   //Get the Correction time (this time will be adjusted to the users timezone)
   var corr = new GlideDuration();
   corr.setValue(current.u_correction_time);

   //Get the local time of the user
   var gdt = new GlideDateTime();
   gdt.getLocalTime();

   //Add/remove time from correction based on the offset of user local time
   corr.add(gdt.getTZOffset());

   //Subtract the correction time from the duration
   dur.subtract(corr);

   //Set Adjusted Duration to dur variable
   current.u_adjusted_duration = dur;

})(current, previous);