Convert from DateTime item in JavaScript

Setup, Configuration and Use Scripts & Rules
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1

I need to set the timeout on a timer that takes milliseconds.
I have a DateTime item.
I need to convert that to epoch milliseconds, then subtract from epoch now, and set the timer with that time delta.
This is JavaScript ECMAv11 using the rules editor.

I am unable to find documentation that describes how to get the epoch from a DateTime item.

2

You don’t need to do all of that. There’s a millisFromNow() method on ZonedDateTime and time,toZDT() will convert the DateTime Item or the rawState to a ZonedDateTime.

var delay = time.toZDT(items.getItem("MyDT")).millisFromNow();

or

var delay  = time.toZDT(items.getItem("MyDT").rawState).millisFromNow();

However, in all cases, as documented, an Item’s .state always returns the String representation of the state. And also as documented, the library can’t process the toString if it includes the timezone.

3

After the latest update (4.0.3, JavaScript), I get from lines like

var alarm=time.toZDT(items.getItem("nextalarm")

the following error message
Error: “nextalarm (Type=DateTimeItem, State=2023-10-05T07:15:00.000+0200, Label=Nächster Alarm, Category=time)” is an unsupported type for conversion to time.ZonedDateTime

Am I missing something here?

4

items.getItem("nextalarm").getState().getZonedDateTime() disclaimer I’m not familiar with jsscripting

5

See OH 4.0.3: Rules (JS Scripting) throws error with "time.toZDT": unsupported type for conversion to time.ZonedDateTime

6

It’s a known bug that has been fixed but not backported.

time.toZDT(items.nextalarm) will normally work except for that bug.

The work around is time.toZDT(items.nextalarm.state) or upgrading openhab-js to a version with the fix. time.toZDT(items.nextalarm.rawState) should also work as a work around.

In order to get at the ZonedDateTime as you attempted it would be items.nextalarm.rawState.getZonedDateTime().

7

Dear all,
Thank you for your helpful responses.
I can confirm that calling the state property instead of the item works.
It seemed the most simple workaround at this time.
Thanks again

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