Timezone with item.state.format()

[JensH]

I got a DateTime Item with correct time.

The Item defined:

Datetime Start “Startzeit: [%1$tH:%1$tM:%1$tS]”

shows Time in local Time. So 19:02:15 UTC is shown correctly as 21:02:15 local time.

No I want to store this DateTime in a String within a rule.

MyItem.sendCommand(Start.state.format(“%1$tH:%1$tM:%1$tS”)

shows 19:02:15 now.

I already tried:

MyItem.sendCommand(Start.state.format(“%1$tH:%1$tM:%1$tSZ”)
MyItem.sendCommand(Start.state.format(“%1$tH:%1$tM:%1$tS%1$tZ”)

but none of these shows the local time. format allways shows UTC time.

Maybe Important: Start had been set with Start.postUpdate(now().millis) before.

Any Idea, how I get the local Time in a String with .format() ???

[rossko57]

@JensH

Datetime Start “Startzeit: [%1$tH:%1$tM:%1$tS]”

Typo? DateTime

I’ve poked around something like this before, without a lot of success, but learnt a little

Worldclock in HAB-Panel oder Display Time from other TimeZone in Basic-UI

You have to remember that all those Item state values are the same time, just with different zones. [%1$tH:%1$tM, %1$td.%1$tm.%1$tY] the java string formatter will always assume your local timezone and display your data converted for that local timezone. I don’t think it is possible to request [%1$xxx] style formatting in any other timezone. I think you would have to use a transformation, probably JS javascript. EDIT - This is quite an interesting puzzle really I loaded a test…

Importantly, what gets held in a DateTime Item state is not always UTC but rather whatever you told it to be … with a timezone ID. If you don’t supply a timezone, it assumes default as your local.

@JensH

Maybe Important: Start had been set with Start.postUpdate(now().millis) before.

I think this is significant. “millis” here is “Unix Epoch” format. There is no timezone in that form, everything is always in UTC.
So joda’s now.millis gives you now in a UTC.
When openHAB postUpdate parses millis into a DateTime, it also knows you must mean UTC and adds that zone to the DateTime.

Demo (I’m in +1 zone just now)

logInfo("test","posting string " + now.toString)
Start.postUpdate(now.toString)
Thread::sleep(100)
logInfo("test","state from string " + Start.state.toString)
logInfo("test","posting millis " + now.millis.toString)
Start.postUpdate(now.millis)
Thread::sleep(100)
logInfo("test","state from millis " + Start.state.toString)

2020-10-15 23:01:25.985 [INFO ] [.eclipse.smarthome.model.script.test] - posting string 2020-10-15T23:01:25.983+01:00
2020-10-15 23:01:26.088 [INFO ] [.eclipse.smarthome.model.script.test] - state from string 2020-10-15T23:01:25.985+0100
2020-10-15 23:01:26.090 [INFO ] [.eclipse.smarthome.model.script.test] - posting millis 1602799286089
2020-10-15 23:01:26.192 [INFO ] [.eclipse.smarthome.model.script.test] - state from millis 2020-10-15T22:01:26.091+0000

Note the stringy now includes my timezone.
The millis now is corrected for my timezone, but expressed in UTC.
Both these are the same time of course, but if you string-format the hours from stringy-now you’ll get 23, and from millis-now you’ll get 22

So the moral is …

@JensH

format allways shows UTC time.

Yes, that is what you loaded your Item with.

To get that back into a local zone is going to take more than just a format, I think.

The internal openHAB code that prepares a DateTime for display in a UI seems to be clever enough to convert everything properly to local timezone (whether you want that or not!), but I do not think that is available to you in rules. You’d have to make your own.

[JensH]

@rossko57

now.toString

This was the solution. Now Item with label works fine and transformation to String with .format(…) too! Thanks a lot.

P.S. Sorry for that Typo, as using SSH from other PC it’s allways tricky to copy, so I just rewrote.