DateTime - Something not right!

Question

Q: Has Salesforce broken away from datetime standards or did datetime standards change or get looser?

I ran this script in Execute Anon:

TimeZone tz = 
  UserInfo.getTimeZone();
System.debug(
  'Display name: ' + 
  tz.getDisplayName());
System.debug(
  'ID: ' + 
  tz.getID());
Datetime zGMT = Datetime.Now();
date dT = zGMT.date();
time tM = zGMT.time();
System.Debug('zGMT: '+zGMT);
System.Debug('zGMT.format : '+zGMT.format());
System.Debug('dT : '+dt);
System.Debug('tM : '+tM);

I got this result:

1. 22:15:14:006 USER_DEBUG [3]|DEBUG|Display name: New Zealand Standard Time
2. 22:15:14:006 USER_DEBUG [6]|DEBUG|ID: Pacific/Auckland
3. 22:15:14:007 USER_DEBUG [12]|DEBUG|zGMT : 2017-01-15 09:15:14
4. 22:15:14:007 USER_DEBUG [13]|DEBUG|zGMT.format : 15/01/2017 10:15 PM
5. 22:15:14:007 USER_DEBUG [14]|DEBUG|dT : 2017-01-15 00:00:00
6. 22:15:14:007 USER_DEBUG [15]|DEBUG|tM : 22:15:14.174Z

All of the results returned by Salesforce are correct except line 6.

If the timestamp is going to represent a timezone ALPHA then it should be an "M" for "Mike" or X for Xray as that is the TimeZone I am in, not sure which due to daylight savings time but definately not Z for Zulu or GMT

EXTRA- I remember about 6 years ago I could insert dates with this format and change the ALPHA at the end to represent my timezone and salesforce would adjust it to GMT for me. 2017-01-15T22:15:14.174M

Any ideas. I really feel like this is a bug.

Answer 1

The Date and Time objects are timezone agnostic; they neither carry nor honor timezone information. You can prove this with a simple script:

System.debug(
    DateTime.newInstance(
        Date.today(), 
        Time.newInstance(0, 0, 0, 0)));
System.debug(
    DateTime.newInstanceGMT(
        Date.today(), 
        Time.newInstance(0, 0, 0, 0)));

In my org, where I'm currently GMT-06:00, I get the following values:

11:04:18.1 (13606970)|USER_DEBUG|[1]|DEBUG|2017-01-15 06:00:00
11:04:18.1 (13646506)|USER_DEBUG|[5]|DEBUG|2017-01-15 00:00:00

As you can see, the first value shows that six hours were added, because I'm in GMT-06:00, and the default debug method outputs GMT all the time, while the second one shows midnight GMT.

You might say that there's a bug with the the system renders the output, because Time is timezone agnostic, but that's the extent of the damage. If you use a Time with newInstance, the time will be appropriate for your configured timezone, while if you use newInstanceGMT, it will be appropriate for the GMT timezone.

Similarly, if you use DateTime.time to get the Time fragment, the Time will be the appropriate hours-minutes-seconds-milliseconds for your configured time zone, while if you use DateTime.timeGMT to get the Time fragment, the Time will be appropriate for the GMT timezone. As a similar demonstration to above:

System.debug(
    DateTime.newInstance(
        Date.today(), 
        Time.newInstance(0, 0, 0, 0)).time());
System.debug(
    DateTime.newInstance(
        Date.today(), 
        Time.newInstance(0, 0, 0, 0)).timeGMT());

Outputs the following values:

11:14:27.1 (1758565)|USER_DEBUG|[1]|DEBUG|00:00:00.000Z
11:14:27.1 (1791286)|USER_DEBUG|[5]|DEBUG|06:00:00.000Z

As you can see, despite both Time values outputting "Z", the hours, minutes, and seconds are appropriate for the timezone. The first one shows midnight in my configured timezone, while the second shows what time it would be when it is midnight in my timezone in GMT. There's no inconsistency with the logic except for the displayed Z, which shouldn't be there.