[SOLVED] Update Virtual Item with value of Group Item multiplied by Fixed Value

Setup, Configuration and Use Scripts & Rules
1

Hi Guys,
Need some help with a rule to estimate cost of energy used

Idea is to get Group KwH multiplied by cost per KwH (22 cents) to then update a virtual item.

I realise I have to change the Group:Number:AVG to Group:Number:SUM for accuracy, but at the moment just trying to work out the rule to get a value

Rule:

rule "Kw into $"
when
    Group gkWh changed 
then
    val production = triggeringItem.state as Number
    VI_Energy_Cost_Month_So_Far.postUpdate(production * 0.22)
end

Items

Group:Number:AVG	gkWh	"kWh"	<energy>	 (Home)	["Energy"]

Number	VI_Energy_Cost_Month_So_Far	"Energy Cost So Far this Month"

Any help would be much appreciated

EDIT: Log File Output from rule

2019-12-23 10:21:31.682 [WARN ] [el.core.internal.ModelRepositoryImpl] - Configuration model 'energy_cost.rules' has errors, therefore ignoring it: [3,5]: no viable alternative at input 'Group'
2

Shouldn’t that be

VI_Energy_Cost_Month_So_Far.value.postUpdate(production * 0.22)
4

I will try that, but per my edit above, I seem to be getting stuck on line 3

Group gkWh changed

I’ve learned this stuff by copying, pasting from the community and then editting to suit my needs, so not too sure where i’m going wrong

5

It appears adding the When statement to look for the Group is the issue. Changing it to an Item cleared the output faults in VS Code and updated the Virtual Item:

rule "Kw into $"
when
    Item gkWh changed 
then
    val production = triggeringItem.state as Number
    VI_Energy_Cost_Month_So_Far.postUpdate(production * 0.22)
end

2019-12-23 12:49:22.510 [GroupItemStateChangedEvent] - gkWh changed from 772.422 to 772.438 through GF_Lounge_Rear_SS_kWh
2019-12-23 12:49:23.028 [vent.ItemStateChangedEvent] - VI_Energy_Cost_Month_So_Far changed from NULL to 169.93636

@Bruce_Osborne FYI when using

VI_Energy_Cost_Month_So_Far.value.postUpdate(production * 0.22)

I got the error below

2019-12-23 12:38:22.816 [ERROR] [ntime.internal.engine.RuleEngineImpl] - Rule 'Kw into $': 'value' is not a member of 'org.eclipse.smarthome.core.library.items.NumberItem'; line 6, column 5, length 33