Org.openhab.core.persistence.HistoricItem.getState() on null

Setup, Configuration and Use Beginners
1

Running into:

2015-12-09 17:18:42.386 [ERROR] [o.o.c.s.ScriptExecutionThread ] - Error during the execution of rule 'Today Water Used': cannot invoke method public abstract org.openhab.core.types.State org.openhab.core.persistence.HistoricItem.getState() on null

My test line is:
logInfo(“Testing”, "Water_Meter = " + Water_Meter.previousState(true).state)

I verified that Water_Meter is being stored in db4o and that is my default persistence for openhab.

2

Finally found the solution:

“Every rule that has at least one status change event trigger, will have the variable previousState available, which can be used inside the execution block.”

I was not using changed as a trigger for my rule.

3

Hi @sipvoip,

could you please specify, what you did wrong?
I don’t get the point :frowning:

4

The triggering rule has to be “changed” vs. “received update” for example. I’m running into this also right now implementing .previousState.state

Best, Jay

5

Thanks. That’s an old post though.
It’s nice to see people being active here ince ages :wink:
That’s why I am always coming back.

By the way: Nowadays I am using previousState a lot as well.
Some in Blockly some in DSL.