Custom Widget Expression Error: TypeError: 'function' is not a function when parsing a config string

Setup, Configuration and Use Widgets
1

Hello everyone,

I am currently building a custom widget for a PV system in openHAB and want to dynamically display the status of multiple smart plugs in a status bar.

My string item (Test_Wallplug_String) receives the following configuration format (Name:TargetState:GroupName):

Plaintext

Wallplug21:off:Group_GF_Storageroom_Wallplug21;Bad Steckdose:on:Group_GF_Bathroom_Wallplug23

My goal is to count in the widget’s status bar how many devices are defined as :on: or :off: in the string without the expression evaluator (=...) crashing with a TypeError: 'function' is not a function.

As soon as I try to evaluate the array using .filter() or .map() with anonymous functions, the UI throws the error.

Question: How do you write a safe string evaluation inside an expression within a custom widget to count items based on specific substrings (like :on:)?

Here is a snippet of my current status bar implementation:

YAML

- component: span
  config:
    content: "=(items[props.stringItem] && items[props.stringItem].state) ? items[props.stringItem].state.split(';').length : 'No data'"

Does anyone have a tip on how best to solve this using widget expressions?

Thank you in advance!

2

Without seeing the expressions you’ve tried, I cannot say why you are getting the error, but most array and string methods do work in widget expressions, so it has something to do with your syntax. Based on what you have provided:

items[props.stringItem].state.split(';').filter((i) => i.includes(':on:')).length.toString()

would output the number of on items.