I’ve just upgraded to openHAB version: v5.0 and just getting some odd values when I get the persistence totals. I’m getting some inconsistent output when I query history for this value vs SQL/db look up.
ie using JS persistence.sumSince I would expect this would return the sum of all from today same as from DB query.
Has anything changed with Javascript persistance?
what is the best way of getting midnight?
Javascript code:
Energy_Mains_energy_interval = items.getItem("Energy_Mains_Total_interval")
var daySoFar = Energy_Mains_energy_interval.persistence.sumSince(time.toZDT("00:00")).numericState //sum since midnight
console.log("Energy: this daily= " + daySoFar);
output:
Energy: this daily= 124353240
SQL code:
select sum(value) from energy_mains_total_interval_46
where time >= '2025-07-27 00:00:00';
nope TZ look ok , this only started after the upgrade to OH 5.0 , is this a bug?
var midnight=time.toZDT("00:00");
var daySoFar = Energy_Mains_energy_interval.persistence.sumSince(midnight).numericState //sum since midnight
console.log("Energy: this daily= " + daySoFar + ' md: '+ midnight);
output
Energy: this daily= 82092600 md: 2025-07-28T00:00+10:00[Australia/Canberra]
I just output the state and its returning the following:
Energy: this daily= 3164219.9999999999812800000 Ws
what is “Ws” Watt Second? and how did was this unit type assigned ?
items:
Energy_Mains_Total_interval:
type: Number
dimension: Energy
label: Energy Mains Total watt minutes
icon: energy
groups:
- Power_meter
tags:
- Sensor
If I divide this value by 3,600,000 I get pretty close to what I expect, how is persistence returning this unit
Persistence saves the state of the Item as a number. During queries and restoreOnStartup it assumes the unit of the Item is the unit of the result.
If no unit metadata is on the Item, the system default is assumed. I thought the default for Energy was Wh but it might be Ws.
Regardless, the Item is using Ws as the unit so the Item’s state is always in Ws and therefore all the values in persistence are in Ws also.
Note that there is a UoM value saved in the Persisted state methods. So you could get the result and convert them to Wh with
var daySoFar = Energy_Mains_energy_interval.persistence.sumSince(midnight).quantityState.toUnit("Wh");
Or you can set the unit metadata on the Item to “Wh” and the Item’s state and therefore the persistence calls will all be in “Wh” by default. However, the changes are not retroactive. The values already stored in persistence will not be adjusted. Furthermore, those old values will be assumed to be in Wh so your calculations with be way off.
The only part I don’t quite understand is how the SQL query is returning the correct value in Wh. I don’t use SQL so it might be that those databases, which can be more flexible than rrd4j for example, do some unit conversions for you. I don’t know.
