Is it possible to combine two transformations?

Setup, Configuration and Use Items & Sitemaps
1

Happy New Year.

So, I’ve got this generic MQTT Thing for an RGB-Zigbee-Bulb and it almost works fine. The only issue(s) are with the value of ‘brightness’ in the color topic as:

“This channel will publish the color as comma separated list to the MQTT broker, e.g. “112,54,123” for an RGB channel (0-255 per component) and “360,100,100” for a HSB channel (0-359 for hue and 0-100 for saturation and brightness).
The channel expects values on the corresponding MQTT topic to be in this format as well.”

But, the value of brightness I get from the Bulb is between 0 and 255.

This is the channel config:

- id: Nous_01_color
    channelTypeUID: mqtt:color
    label: Nous_01_color
    description: color
    configuration:
      postCommand: false
      retained: false
      formatBeforePublish: '{ "x": %s, "y": %s, "brightness": %s}'
      commandTopic: zigbee2mqtt/nous_01/set/color
      colorMode: XYY
      stateTopic: zigbee2mqtt/nous_01
      transformationPattern: DSL:|transform("JSONPATH", "$.color.x",
        input)+","+transform("JSONPATH", "$.color.y",
        input)+","+transform("JSONPATH", "$.brightness", input)

And I was wondering if there is a way to have an additional transformation for the last value. My attempts to get it running failed so far…

2

Why don‘t you just chain the transformations with the intersection character (like shown in the documentation)?

3

I think intersection does not help here, as it’s about giving Value a, b and c.

For incoming messages, a script seems to be the appropriate way (and of course it’s possible to add something like

transformationPattern: DSL:|transform("JSONPATH", "$.color.x",
        input)+","+transform("JSONPATH", "$.color.y",
        input)+","+(Integer.parseInt(transform("JSONPATH", "$.brightness", input))*2.55).toString

(did not verify)

For outgoing messages, there is also the option to use a script transformation, I guess it’s the best option here.

1 Like
4

You see - I’ve already set up a script (NousDown.js) for this transformation in the transform folder:

(function(i) {
    if(input >= 0)
    {
	return input / 255 * 100;
    }
    else
    {
	return null;
    }
})(input)

But I don’t know how to make use of it as I’m struggling with the syntax in the channel config.

I tried things like:

transformationPattern: DSL:|transform("JSONPATH", "$.color.x",
        input)+","+transform("JSONPATH", "$.color.y",
        input)+","+transform("JS", NousDown.js, (transform("JSONPATH", "$.brightness", input)))

And I now tried your attempt/suggestion, but it isn’t working either.

5

there is another thread with the same topic :slight_smile:

6

Well, not the same topic, but another attempt to archive the same goal - which I will have a look at. Thanks again, Udo.

7

I did test with success (as a *.things definition):

        Type color  : col "Color"      [ colorMode="XYY", commandTopic="test/zigbee2mqtt/p3z/set", stateTopic="test/zigbee2mqtt/p3z", 
        transformationPatternOut="DSL:|val col = input.split(',') var my = '{\"brightness\": ' + (Float.parseFloat(col.get(2))*255/100).toString + ', \"color\": {\"x\": ' + col.get(0)  + ',\"y\": ' + col.get(1) + '}}' my", 
        transformationPattern="DSL:|transform('JSONPATH','$.color.x',input) + ',' + transform('JSONPATH','$.color.y',input) + ',' + (Integer.parseInt(transform('JSONPATH','$.brightness',input))*100/255)" ]

or (the same) as yaml code:

channels:
  - id: col
    channelTypeUID: mqtt:color
    label: Color
    description: null
    configuration:
      retained: false
      postCommand: false
      transformationPatternOut: "DSL:|val col = input.split(',') var my =
        '{\"brightness\": ' + (Float.parseFloat(col.get(2))*255/100).toString +
        ', \"color\": {\"x\": ' + col.get(0)  + ',\"y\": ' + col.get(1) + '}}'
        my"
      formatBeforePublish: "%s"
      commandTopic: test/zigbee2mqtt/p3z/set
      colorMode: XYY
      stateTopic: test/zigbee2mqtt/p3z
      transformationPattern: DSL:|transform('JSONPATH','$.color.x',input) + ',' +
        transform('JSONPATH','$.color.y',input) + ',' +
        (Integer.parseInt(transform('JSONPATH','$.brightness',input))*100/255)
8

And I ran into another issue:

[WARN ] [t.generic.ChannelStateTransformation] - Transformation service JS for pattern NousOut.js not found!

And it’s correct, there is no such transformation installed - but also not available.

grafik
grafik978×482 40.5 KB

I’ll try your attempt now…uff.

9

That’s correct, as there is no script transformation service at all.

The thing is, you can now use any script engine which is installed to do a script transformation.
In older openHAB versions you had to install JS Transformation Service and you were bound to JavaScript Scripting for Transformations.
The Log message is a bit vague here :slight_smile: but you’ll simply have to install the JavaScript Scripting engine.

10

Okay, got it. In order for JS to be functional I had to install the script engine. How ever, I now got it working using your transformation patterns. I only had to change

(Integer.parseInt(transform('JSONPATH','$.brightness',input))*100/255)

to

(Float.parseFloat(transform('JSONPATH','$.brightness',input))*100/255)

Thank you, Udo.

1 Like