MapDB Persistence Not Working?

Setup, Configuration and Use Installation
1

Hi all,

Taken my first step into persistance today but it doesn’t seem to be going too well…I wanted to install mapdb so I can use the previous state of my items in rules. Heres what I have done:

  1. Installed mapdb as per instructions
  2. restarted OH
  3. Set up my mapdb.persist file
// mapdb persistence - store every item previous state - restore them on startup

Strategies {
	default = everyChange
}
Items {
	gMapDB* : strategy = everyChange, restoreOnStartup
}
  1. Added the gMapDB to an items file
Group   gMapDB            "gMapDB Presistence"
  1. Then added the group gMapDB to the items I want to store the previous state, eg
String   vGPCurrLoc      "Current Location [%s]"       (gMapDB)

  1. Restarted OH again

  2. Made sure the item vGPCurrLoc updated it’s status, (this item actually updates every 5 minutes anyway)

  3. Added the following code into a rule

vGPCurrLoc.previousState("mapdb").state.toString
  1. Am currently getting the following in the log:
Rule 'GP iPhone Location detection': An error occurred during the script execution: Could not invoke method: org.eclipse.smarthome.model.script.actions.BusEvent.sendCommand(org.eclipse.smarthome.core.items.Item,org.eclipse.smarthome.core.types.Command) on instance: null

Now that reads to me like the item previous state is null, ie it hasn’t been assigned a value yet…

I know it has certainly updated so I’d expect to see something in there.

Does anyone have any ideas or pointers please???

2

previousState doesn’t make any sense with mapdb. It stores one value only, and it is the one the Item last changed to - i.e it is “nowState”.

3

Ah, so how do I refer to it in a rule?

4

You’ll have to use another persistence such as rrd4j (numbers only) or influxdb.

5

Ah, so…that was probably going to be my next question. I didn’t quite know which persistence option to go for.

From what you’ve just said, I now assume:

mapdb is good for system restart state
Influxdb is good for item previous state

Is that right? If so, how does the system / do you / rules determine how to use which one?

6

Hint

7

So the bit in brackets determines the persistence service it calls?

8

As described here

It’s the last string in the bit in brackets that is the selector
xxx.previousState() - use default service
xxx.previousState(“influxdb”)
xxx.previousState(true,“influxb”)

9

Wonderful, thanks…

I’m now off to see how easy / hard getting influxdb onto my OH setup is…:+1: