item.persistence.lastUpdate() not always working

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1

Hello everyone,

after the migration to version 4.2.1 I have the following behavior, but I’m not sure if it was the same before:

In a js-rule I call the .persistence.lastUpdate() and have the problem that very often null comes out!

2024-09-24 09:46:03.484 [INFO ] [.file.generic_min-_and_max_values.js] - Generic Min- and Max values js | 1727163963451 | forEach | loopKey: minDay item.persistence.lastUpdate(): 2024-09-24T09:46:03+02:00[Europe/Berlin]

2024-09-24 09:50:41.634 [INFO ] [.file.generic_min-_and_max_values.js] - Generic Min- and Max values js | 1727164241625 | forEach | loopKey: minDay item.persistence.lastUpdate(): null

The database looks like this:
image

The item is defined as follows:

item = items[event.itemName];

The rule is very long and contains some loops…

Can anyone explain this behavior? Is this simply a runtime error, but if so, why isn’t an older date returned instead of null?

openHAB 4.2.1
persistence: jdbc as standard

2

Hi Tobias,

see discussion on this thread.

long story short:

  • if there’s an update of the item value in parallel to the time your lastUpdate-call, the response is ‘null’
  • there’s an lastUpdate attribute in the making on the item itself - no persistence needed, coming with 4.3 if all works out
  • for the time being, you could insert an if-clause on the lastUpdate for “null” and then try again with the next rule-call…
3

Ahh, didn’t see that :slight_smile:

As a workaround, I now have a while loop that waits for the result for a maximum of 5 seconds:

        if(item.persistence.lastUpdate() == null)
        {
            var sleep = true;
            while(sleep == true)
            {   
                //log(ruleName + ' | sleep | item.persistence.lastUpdate(): ',item.persistence.lastUpdate());
                var newTime = time.ZonedDateTime.now().toInstant().toEpochMilli();
                if((newTime-timeStamp) >= 5000 || item.persistence.lastUpdate() != null)
                {
                    log(ruleName + ' | sleep | item.persistence.lastUpdate(): ',item.persistence.lastUpdate());
                    sleep = false;
                }
            }
        }
        if(item.persistence.lastUpdate() == null)
        {
            log(ruleName + ' | .lastUpdate() is null!' );
            return;
        }

Maybe someone can still use this :slight_smile: