UoM in group: change unit

Setup, Configuration and Use Items & Sitemaps
1

First my items.
Items:

Group:Number:Speed:AVG	Rainintensity							"Regenintensiteit [%.2f mm/h]"									(Weather)
Number:Speed 			Buienradar_Current				"Regenintensiteit [%.2f mm/h]"		(Rainintensity, RestoreOnStartup)					 {channel="buienradar:rain_forecast:buienradar:forecast_0"}
Number:Speed			Buienradar_Forecast5			"Regenintensiteit (over 5min) [%.2f mm/h]"		(Rainintensity)		{channel="buienradar:rain_forecast:buienradar:forecast_5"}
Number:Speed			Buienradar_Forecast10			"Regenintensiteit (over 10min) [%.2f mm/h]"		(Rainintensity)

In the sitemap the group and all the items show the value in mm/h.

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But when I use the rules or use smarthome:status in the console, the items are still mm/h but the group is km/h

openhab> smarthome:status Buienradar_Current
0.1 mm/h
openhab> smarthome:status Rainintensity
5.999995200003839666666666666666668E-8 km/h

How do I change the unit in the group (for the stored value)?

2

Why would you need to do that? It doesn’t matter in rules, you can specify the wanted units e.g. for some comparison.
I can think of a good reason - say you wanted to persist for charting purposes.

There isn’t a direct way to do what you want.
It can’t really follow member Item units, they might all be different.
I think it could be a sensible enhancement if Group aggregation functions for a QuantityType Group looked at [state presentation] for a default unit, the way that bindings can.
The fallback would be system default, which is I guess what you get now.

3

That’s true. Never thought of that. Mostly I use a “dirty” hack and strip of the UoM → Item.state as QuantityType<Number>).intValue
With my hack I get the wrong number (obviously).

Thank for your reaction.

4

Right. So a unit based comparison would be
if (myGroup.state > 1.5 | mm/h)

I think I’ll have a little play and may make an enhancement request anyway.