[Solved] How to to use the content of a string as item name

Setup, Configuration and Use Scripts & Rules
1

Hi All,

I’m quite new to openhab so please be patient. I’m very impressed by the functionality and ease of getting started. So thumbs up to all the developers and people involved :grinning:

I am monitoring the temperature in all my rooms. Whenever the current temperature (IST) is more then 2 degrees below the wanted temperature (SOLL) I want to receive an email.

So for each room I have a pair of Numbers which are read from KNX:

Number Heating_Temp_WZ “Wohnzimmer [%.1f °C]” (Heating) { knx = “<3/1/1”}
Number Heating_Temp_WZ_Soll “Wohnzimmer Soll [%.1f °C]” (Heating) { knx = “3/1/11+<3/1/21”}

This is my approach:

rule “Room too cold”
when
Item Heating changed
then
var changedTemperatures = Heating.members.filter(x|x.changedSince(now.minusSeconds(30))).map[it]
changedTemperatures.forEach [ room |
logInfo(“Heating”, "room too cold: " + room.name) // --> “Heating_Temp_WZ”

		var sollName = ( room.name + "_Soll") as String  
		logInfo("Heating", "name: " + sollName)  // --> "Heating_Temp_WZ_Soll"
		
		// FIXME: how to get from sollName to item?
		
	   var soll = sollName.state as DecimalType
	   var ist = room.state as DecimalType

		logInfo("Heating", "soll:"  + soll + "  ist:" + ist)
   
   		if ( soll.floatValue - ist.floatValue > 2.0) {
	   		logInfo("Heating", "sending email")
   		}
   	]

end

Of course I could harcode the pairs in my rule file. But there must be a smarter way reusing the already defined items?!

Any hints?

Thanks a lot
Karl

2

I found the solution. More an xtend “problem” then openhab. I can just filter the member of Heating again and search for the SOLL-Name.

Here ist the working solution:

rule “room too cold”

when

Item Heating_Temp_WZ 		changed or

Item Heating_Temp_Bad 		changed or

...

Item Heating_Temp_Flur 		changed

then

    logInfo("Heating", "changed")

    var changedTemperatures = Heating.members.filter(x|x.changedSince(now.minusSeconds(30))).map[it]

    changedTemperatures.forEach [ room |

	    logInfo("Heating", "room temp changed: " + room.name)

	    val sollName = ( room.name + "_Soll") as String			
	    var sollItems = Heating.members.filter(x|x.name == sollName.toString).map[it]   // <-- this does the trick
	    var soll = sollItems.head.state as DecimalType
	    var ist = room.state as DecimalType

	    logInfo("Heating", "Soll:"  + soll + "  Ist:" + ist)
   
   	    if ( soll.floatValue - ist.floatValue > 2.0 ) {
	   	logInfo("Heating", "sending email")
	   	...
   	    }
   	]

end

So maybe this will help some other newbie. Thanks to everyone so far.

2 Likes