Property bindings of type "camunda:executionListener" ignores name property

[AlexanderSkrock]

Describe the Bug

Element templates including an execution listener binding do not respect the configured property name. In consequence, it currently is not possible to define a class-based execution listener as template.

Per documentation (https://unpkg.com/@camunda/element-templates-json-schema/resources/schema.json) the name attribute at properties/property/binding/name is not specific to any type. In additional this currently breaks the properties panel.

Steps to Reproduce

1. Create an element template for service task
2. Add a property binding of type "executionListener"
3. Set the property name to bind to "class"
4. Create new task element within Modeler
5. Apply the configured template
6. Now the properties panel is frozen and the console shows an error.
7. The configured class name is not set as "class" property but as "value" which would not work on execution. This leads to the afore mentioned error.

Mine looks similar to this:

{
  "$schema": "https://unpkg.com/@camunda/element-templates-json-schema/resources/schema.json",
  "name": "Name",
  "id": "id",
  "version": 1,
  "appliesTo": [
    "bpmn:Task"
  ],
  "elementType": {
    "value": "bpmn:ServiceTask"
  },
  "properties": [
    {
      "label": "Implementation Type",
      "type": "Hidden",
      "value": "path.to.class",
      "binding": {
        "type": "camunda:executionListener",
        "event": "start",
        "name": "class"
      }
    }
  ]
}

Expected Behavior

The "name" property should be evaluated for execution listeners.

I discovered the behaviour is defined here: CreateHelper.js#L153. Whatever is calculated as parater value is assgined to "value". The default should not point to "value" but rather to "binding.name". If that is not configured "value" seems okay. In theory only the following line would need a change: CreateHelper.js#L173

Environment

• OS: Windows 10
• Camunda Desktop Modeler 5.0.0

I would happily try to create a pull request, if that is okay to you.

Kind regards
Alexander Skrock

[philippfromme]

@pinussilvestrus Can you confirm that this was the intended behavior? I can't find a test verifying this.

[pinussilvestrus]

The schema rules seem to not strictly validate the binding properties for each binding type. This was reported via camunda/element-templates-json-schema#109.

According to the docs, name in combination with type=executionListener is indeed not supported. So we can either support it or add stricter validation to avoid confusion.

[AlexanderSkrock]

Hi @philippfromme and @pinussilvestrus ,

you arguments sound reasonable. Maybe the name attribute was not originally made for this use case. Still, I would appreciate if your decision includes that we enable class-based execution listeners for element templates.

Another approach would be to use a more specific attribute such as class. However I thought using value in combination with name would be a good idea because it is very similar how script-based execution listeners work. They also use value for the code to execute and scriptFormat to define we have a script and the scripting format.

Kind regards
Alexander Skrock

[barmac]

I'm moving this to backlog as a potential enhancement. We are also happy to accept external contributions.

[AlexanderSkrock]

Thank you for your evaluation and I would be happy to contribute, @barmac .

I just realized I deleted my fork, when cleaning up my repos and forgot about the open pull request. Luckily I still had my changes locally and was able to open a new pull request.