JS Transformations in item channel definition

Setup, Configuration and Use Items & Sitemaps
#1

Hi,
I am moving all my bindings to V2 in order to migrate to OH3.

So far I encountered one issue that I haven’t managed to solve yet:
I want to transform a state received from a binding.

This is my Items definition:

Number APC_TIMELEFT (gAPC) {channel="networkupstools:ups:ups:batteryRuntime" [profile="transform:JS", function="sec2min.js", sourceFormat="%.1f"]}

This is my JS transformation (sec2min.js)

(function(i) {return i / 60; } ) (input)

And this is the error message:

2021-01-29 09:13:47.407 [WARN ] [iles.JavascriptTransformationProfile] - Could not transform state '8308.0 s' with function 'sec2min.js' and format '%.1f'

I tried without sourceFormat and with sourceFormat="%d" or "%.0f" or "%.1f s" but get the same type of error.

(I know I could transform the seconds to minutes using the Time unit of measure, but I want a more general way using the transformation service for future use. So plese help find the error in the above syntax.)

#2

Seems like a version of this bug

This comes from the binding supplied defaults and is misapplied to transform output.

#3

The value input into the transformation seems to be ‘8308.0 s’, i.e with the unit attached. I think you need to handle that properly in your javascript. Try changing to

(function(i) {return parseFloat(i) / 60; } ) (input)

and see if that helps.

#4

So I should not use sourceFormat in transformations?

Tried the suggestion without sourceFormat but I receive no error message but the state = NULL

#5

I’m actually not sure if the format specifier works, it seems that the incoming state is converted to a String before the format specifier is applied, and the ‘f’ format specifier is only applicable for floats/doubles. Try removing it from the item definition.

Edit: saw now you already tried that and it didn’t work. Not sure how to do then…

#6

Can’t test ATM, so use the following with caution:
IMHO your js function expects an input which can be parsed to a number, however it gets a number with a dimension (“s”). I’d try to split that dimension from the number, like:

var temp= i.split (" ");
return temp[0]/ 60;

If that isn’t according your more generell solution, try to remove any non-member character using a reflex or the like.

#7

SourceFormat is about formatting raw data from binding as it gets given to the transform. In almost every case you can let that default (%s) and transform deals with a string.
As an aside, remember that any format produces a string - the transform input is always a string.

Your problem is the other end of the transform, the output to Item, and it is beyond your control. It’s a bug.

#8

OK, a few things to mention here to be complete.

The Channel is returning a Number:Time value so if you make your Item be a Number:Time too then you don’t need to do any transformations at all. You can just change the State Description to use %.2f min and it will convert it to minutes for you.

You can also use the DateTime formatting to show Hours:Minutes:Seconds I think. If you use %s it will display the value as a DateTime (with 1970-01-01 as the date).

In your rules you can use the units too. For example, to see if it’s less than 2 hours

if(APC_TIMELEFT.state < 2 |h) {

As for the transform, i is getting the String “8308.0 s”. You need to strip off the units and then you should be able to parse it into a float you can do math.

var num = parseFloat(i.split(" ")[0]);

NOTE: all of this is assuming that everything is working correctly and not related to the bug rossko57 linked to.