The Secrets of GlideDateTime

[The SN Nerd]

Working with Dates in ServiceNow can be quite challenging.

In this Blog Series, I will list some of the common mistakes and provide some secrets to using GlideDateTime that you might not be aware of.

Topics

Date Formatting

Scheduled Tasks using Date GlideDate

Calculating Business Duration In Schedule

Date Formatting

Date formatting is actually incredibly easy in ServiceNow. I have seen lots of posts with complex code to format dates into day names, month names and everything in between - often with 10's of 100's of lines of code. But it doesn't have to be this hard! It is actually very easy. You can do all your formatting using one function, provided OOTB!

GlideDateTime

Example

var gdt = new GlideDateTime("2011-02-02 12:00:00");
gdt.setDisplayValue("20-5-2011 12:00:00", "dd-MM-yyyy HH:mm:ss"); //uses current user session time zone (US/Pacific)
gs.print(gdt.getValue());

setDisplayValue() uses the SimpleDateFormat (Java Platform SE 7 ) , which is fully documented!

Get current date in any format (GMT)

Current Date/Time: 16th September 2020, 08:26:22 AM (AWST +8)

var gDate = new GlideDate();
var formattedDate = (gDate.getByFormat('yyyy-MM-dd HH:mm:ss'));
gs.print(formattedDate);

2020-09-16 00:26:22

Get current date in any format (Local)

Current Date/Time: 16th September 2020, 08:26:22 AM (AWST +8)

var gdt = new GlideDateTime();
var gd = new GlideDate();
gd.setValue(gdt.localTime);
gs.print(gd.getByFormat("yyyy-MM-dd HH:mm:ss"));

2020-09-16 08:26:22

Get the hour of a given date (Local)

Current Date/Time: 16th September 2020, 08:26:22 AM (AWST +8)

var gdt = new GlideDateTime(); // datetime of your choosing in here
var gd = new GlideDate();
gd.setValue(gdt.localTime); 
var hour = parseInt(gd.getByFormat("HH"));
gs.print(hour)

8

Converting Formats

Incoming Format: 20171216 01:23:45
Simple Format: yyyyMMdd HH:mm:ss

var date = '20171216 01:23:45';
var simpleDateFormat = 'yyyyMMdd HH:mm:ss';
var gdt = new GlideDateTime();
gdt.setDisplayValue(date,simpleDateFormat);
gs.print(gdt.getDisplayValue());

16-12-2017 01:23:45

Converting Day and Month Names with AM/PM

Incoming Format: Friday, August 18, 2017 8:00 AM
Simple Format: E, MMMM dd, yyyy K:mm a

var newDate = 'Friday, August 18, 2017 8:00 AM';
var gdt = new GlideDateTime();
gdt.setDisplayValue(newDate, "E, MMMM dd, yyyy K:mm a");
var dateTimeForField = gdt.getDisplayValue();
gs.print(dateTimeForField);

2017-08-18 08:00:00

Getting the Name and Day of Month

Incoming Format: new GlideDateTime();
Simple Format: EEEE dd MMMMM

var gDate = new GlideDateTime().getDate();
gs.print(gDate.getByFormat('EEEE dd MMMMM'));

Thursday 14 December

Add days to any format

Incoming Format: 10 Jul 2018 12:30:00
Simple Format: EEEE dd MMMMM

var date = '10 Jul 2018 12:30:00';
var simpleDateFormat = 'dd MMMM yyyy HH:mm:ss'; // Simple Date Time format
var gdt = new GlideDateTime();
gdt.setDisplayValue(date,simpleDateFormat); //Set time using current TZ
gs.addInfoMessage(gdt.getDisplayValue()); // Output time in current TZ

2018-07-10 12:30:00 PM

Once your GlideDateTime object has the correct time, you can manipulate it as you need.

gdt.addDays(7);
gs.addInfoMessage(gdt.getDisplayValue());

2018-07-17 12:30:00 PM

And back again to your original format, with the added 7 days

var gd = gdt.getLocalDate();
var gt = gdt.getLocalTime();

gs.addInfoMessage(gd.getByFormat('dd MMM yyyy') + gt.getByFormat(' HH:mm:ss'));

17 Jul 2018 12:30:00

Scheduled Tasks using Date GlideDate

It is a fairly common requirement - generate a task every day of the week, excluding the weekend. If you do a quick search for this, you will see lots of versions of the code below which uses Date():

(function doNotUseThisCode() {
	var now = new Date();
	var day = now.getDay();
	var result = false;
	if(day != 0 && day != 6) {
		result = true;
	}
	return result;
})();

Please do not use this code!
It is wrong!

If you run the code below (run from a Perth Instance in Australia)

gs.addInfoMessage(new Date().toString());
gs.addInfoMessage(new GlideDateTime().getDisplayValue());

 

You get the following output:

Tue Jan 02 2018 05:38:49 GMT-0800 (PST)
02-01-2018 21:38:49

What is going on here?

The output of Date().toString() is not using your TimeZone!

now.getDay() is getting the day in PST!

I am from Perth, Australia (GMT + 😎 which means that my Task will spawn on Saturday and not on Monday because it is still Friday and Sunday retrospectively in PST.

And you can bet that is what happened when the code went into Production... 😕

Let's utilize what we learned from Date Formatting for a more readable and TimeZone agnostic solution using GlideDate instead:

(function isWeekday() {

	var isWeekday;
	var gDate = new GlideDate(); //Uses your Timezone!
	var day = gDate.getByFormat('EEEE') + ""; // Gets name of day, retruns Java object
	switch(day) {
		case "Saturday":
		case "Sunday":
			isWeekday = false;
		break;
		default:
			isWeekday = true;
	}

	return isWeekday;

})();

Calculating Business Duration In Schedule

There are a few different ways to do this, either through the SLA API or GlideSchedule.
GlideSchedule seems to be the cleanest way:

function getBusinessDuration(scheduleID, gdtStart,gdtEnd) {
    var sched = new GlideSchedule(scheduleID);
   return sched.duration(gdtStart, gdtEnd).getDurationValue();
}

Let's assume our Schedule has a business day of 11 hours, Monday to Friday.
We would, therefore, expect the duration of a calendar week in business hours to be 55.

var oneWeekAgo = new GlideDateTime();
oneWeekAgo.addDays("-7");

getBusinessDuration(
  'c2f96f156fc1750029ca5e0d5d3ee427', 
  oneWeekAgo, 
  new GlideDateTime()
);

2 07:00:00

There are 24 hours in each day.
2 days = 48 hours
48 + 7 = 55 hours