[SOLVED] Dummy Item with predefined value / state

[aksnet (Andreas Kuhn)]

Hi Guys,
this is my actual item for a HomeMatic Wireless Window Rotary Handle Sensor:

String Emily_Fenster_Status “Fenster Emily Status [MAP(fenster_de.map):%s]” (gBad, gFenster) {channel=“homematic:HM-Sec-RHS:6d1a3e28:NEQ1760269:1#STATE”}

My transformation:
CLOSED=geschlossen
OPEN=offen
TILTED=gekippt
NULL=undefiniert

Based on these information i enable or disable my heating control widget.
So far so good.

But now i have some rooms without window sensor and would like to avoid to create 2 separate widgets and therefor i was looking for a way to create an item without binding but with predefined value,

This is just a sample format i was thinking of:
String Flur_Fenster_Status "Fenster Flur Status = CLOSED (gFlur, gFenster)

Can someone please help me in finding the correct format?

Thanks
Andreas

[rlkoshak (Rich Koshak)]

Design Pattern: Encoding and Accessing Values in Rules

Edit: Added link to item_init library. Please see Design Pattern: What is a Design Pattern and How Do I Use Them for how to read and use a DP. Problem Statement Often a user has the desire to be able to store and retrieve a series of constants or other values in a Rule. For example, a user may have an RFID reader and want to store the list of authorized and disallowed IDs in a flexible manner. As another example, one may be sending commands to a gateway and need to include the ID of the target…

[aksnet (Andreas Kuhn)]

Hi Rich,
thanks for sharing this. But i failed to implement it so far.
I even tried to simply use the sample with the switch, but what i get back is always NULL when i print it out in a template via {{itemValue(‘DUMMY_Fenster_Status’)}}.

I tested as Item:
Switch DUMMY_Fenster_Status “Fenster DUMMY Status” (gFenster) {state = “ON”}
Switch DUMMY_Fenster_Status “Fenster DUMMY Status” (gFenster) {value = “ON”}
String DUMMY_Fenster_Status “Fenster DUMMY Status” (gFenster) {state = “CLOSED”}
String DUMMY_Fenster_Status “Fenster DUMMY Status” (gFenster) {value = “CLOSED”}

Nothing has worked. Or is for the virtual item really a rule required?

Thanks
Andreas

[rlkoshak (Rich Koshak)]

@aksnet

Or is for the virtual item really a rule required?

As documented in the linked Design Pattern, you have to use a rule. You cannot initialize the state of an Item in the .itmes file. The { } are for binding configs and nothing else.

[aksnet (Andreas Kuhn)]

Hi Rich,
thanks again! You are the code expert
But based from this post
https://community.openhab.org/t/design-pattern-encoding-and-accessing-values-in-rules/36210?source_topic_id=36298

and this sample:

Switch RFID_12345 "Bob's ID" (Authorized) { expire="1m,state=OFF" }

and this text

This approach is well suited for situations where

no system started rule required to boot strap the value, value is coded into the Item so only the Items need to be changed to add, remove, modify the values.

i thought hardcoding a simple value would be possible.

But i got it working now:
My final String item:

String DUMMY_Fenster_Status "Fenster DUMMY Status [MAP(fenster_de.map):%s]" <window> (gFenster)

My rule running every minute

rule "set dummy values"
when 
    Time cron "0 * * * * ?" //every minute
then
	DUMMY_Fenster_Status.sendCommand("CLOSED")
end 

Greetings
Andi

[imhofa (Andreas Imhof)]

Why are you setting the dummy item every minute?

I think it is better to use a “system started” triggered rule. Then the dummy item is set once (and is not changed anymore).

Andreas

[aksnet (Andreas Kuhn)]

Hi Andreas,
thanks for the hint.

I am not that familiar with these rules (yet), so i try to avoid using them as much as possible.
My homematic system variables are updated every minute via a rule, so i just took this one and modified it.

I have now changed to when “System started”.

Thank you
Andreas

[rlkoshak (Rich Koshak)]

@aksnet

But based from this post

If you read that post and look at the examples you will see that none of them attempts to set the state of the Item from the .items file.

@aksnet

expire=“1m,state=OFF”

Expire is a binding. That is a binding configuration, not the setting of an Item’s state from the .items file.

@aksnet

value is coded into the Item

Should have read “encoded into the Item’s name”. I’ve updated the post to add that one important word.

@aksnet

i thought hardcoding a simple value would be possible

If it were possible I would not have needed the DP and the three different approaches to do it.

I’m glad you got it working but also ask why you do not use a System started the like the DP linked to above demonstrates in example 1.

[aksnet (Andreas Kuhn)]

@rlkoshak

If you read that post and look at the examples you will see that none of them attempts to set the state of the Item from the .items file.

Hi Rich, i blame the fact not beeing a nativ english speaker for having some issues to understand this the first try.

@rlkoshak

Expire is a binding. That is a binding configuration, not the setting of an Item’s state from the .items file.

Now it is clear

@rlkoshak

Should have read “encoded into the Item’s name”. I’ve updated the post to add that one important word.

Perfect, thanks. So it might be easier to understand it.

@rlkoshak

If it were possible I would not have needed the DP and the three different approaches to do it.

But it would be cool and handy to set a definded state directly in the item definition. Maybe room for a Feature Request?

@rlkoshak

I’m glad you got it working but also ask why you do not use a System started the like the DP linked to above demonstrates in example 1.

I changed now to System started. I had this rule running every minute already in place and so it was the easiest for me to just add it. But well simply creating a new rule file was also easy and quick done afterwards

Many thanks again for your help. Your support and this great community is much appreciated!

Andreas