Detecting Null variable

vaderag

I have a particular Z-wave PIR that occasionally (yet frequently) decides not to report luminance

I have a flow that uses this luminance, however obviously if there is no value it does not activate. I would like this to activate when luminance is 'null'

I have tested outputting the value to my phone and it receives the string 'null', although the display next to the tag in Homey is '-'

I have tried setting up a logic variable as an OR command for #Luminance = null (and every card variant of it that i can) and also tried with the - but neither seem to activate 

Can anyone advise how I can use this value?
Thanks!

Edit: I've even noticed that the Battery alarm is also reporting null when this issue occurs, so tried the following and still no dice...

Rocodamelshe

Using tags in normal logic cards is still not possible as far as i know. There are GH issues for it.

vaderag

Rocodamelshe said:

Using tags in normal logic cards is still not possible as far as i know. There are GH issues for it.

I use them elsewhere successfully...
E.g if luminance < 30

Rocodamelshe

Ok. GH issues can be closed then.

vaderag

Rocodamelshe said:

Ok. GH issues can be closed then.

Well, they're clearly not perfect given my initial post, but I do have multiple flows successful in using a tag in a logic card...

If we could establish the string / value for null I'm sure it could work. 
I think part of the problem however may be that it's a number value tag and I'm trying to match it to the string which is reported

Rocodamelshe

But is actualy a workaround for missing values in the devices?
If value fails then do something?
Maybe best to open a GH issue then for adding the -

vaderag

Rocodamelshe said:

But is actualy a workaround for missing values in the devices?
If value fails then do something?
Maybe best to open a GH issue then for adding the -

Can't find a workaround...

GeurtDijker

I guess Athom filters out the 'null' variables to prevent unexpected behavior and this is best for most new Homey users. 

I think if we tell @Kees de Vries that the temperature is null he will call for Rayonhoofden  as he doesn't know the difference with the Temperature of 0  ;-) 

If you really want to know it is possible using an one-liner in Homeyscript. 
I tested two numeric  Tags from which one is a 'null'



Paste below  in a new script ( testForNull.js ) 

// testForNull.js Test first argument if it is 'null' 
if ( args[0] === 'null' ) { log("Argument is null");return true} else { log("Argument is Not null"); return false};

And drop the tag in the "Run a Script with an argument" but remove the spaces around the tag!

Keeping the Homeyscript open shows the result  when testing. 

vaderag

@GeurtDijker
Thanks so much for the script - worked a treat (once I'd worked out how to actually add a HomeyScript!!