Conditional properties are not reliably rendered

[christian-konrad]

Describe the bug

Property conditions are not evaluated right when applying a template where the referenced dropdown value has no explicit default. Also, the value of a binding is not changed to the specified default value when using multiple but mutually exclusive properties with different default values (i.e. to simulate conditional default values). The latter is a behavior requested by a partner that implements a whole connector ecosystem.

Steps to reproduce

1. Create a template with a dropdown with no default option specified (the first option will be rendered)
2. Create 2 dependent properties, but with same binding, and both depending on different dropdown option. The first is dependent on the first dropdown option. Both have different default values.
3. When applying the template, even if the first dropdown option is visually selected, the dependent property isn't shown
4. Switching the dropdown value does not change the default value of the field/binding
5. The field must be rendered invisible first (by invalidating all conditions), before the default value can change

See the video and template (next comment)

Bildschirmaufnahme.2022-07-14.um.17.12.52.mov

Expected behavior

• Either the dropdown renders no value if no default is set, or if the first value is rendered, all conditions to this must be evaluated.
• Default values of same bindings should change when conditions apply, as this is explicitly defined in the template (otherwhise, the template should prohibit multiple properties with same binding)

Environment

• Camunda Modeler Version: 5.1.0
• Execution Platform: C8
• Installed plug-ins: None

[christian-konrad]

  {
    "$schema": "https://unpkg.com/browse/@camunda/zeebe-element-templates-json-schema/resources/schema.json",
    "name": "Same Binding Test",
    "id": "same-binding-test",    
    "appliesTo": [
      "bpmn:ServiceTask"
    ],
    "properties": [
      {
        "id": "default-changer",
        "label": "Change the default",
        "type": "Dropdown",
        "choices": [
          {
            "name": "Set it as 1",
            "value": "set-1"
          },
          {
            "name": "Set it as 2",
            "value": "set-2"
          },
          {
            "name": "Reset",
            "value": ""
          }
        ],
        "binding": {
          "type": "zeebe:taskHeader",
          "key": "ignore"
        }
      },
      {
        "label": "Test",
        "type": "String",
        "value": "1",      
        "binding": {
          "type": "zeebe:input",
          "name": "test"
        },
        "condition": {
          "property": "default-changer",
          "equals": "set-1"
        }
      },

      {
        "label": "Test",
        "type": "String",      
        "value": "2",
        "binding": {
          "type": "zeebe:input",
          "name": "test"
        },
        "condition": {
          "property": "default-changer",
          "equals": "set-2"
        }
      }
    ]
  }
]

[pinussilvestrus]

I believe it should work the same as for any other templated "Dropdown" property. When no value is given, it should display empty.

{
  "name": "Dropdown",
  "id": "Dropdown",
  "appliesTo": [  "bpmn:ServiceTask"  ],
  "properties": [
    {
      "label": "Task Priority",
      "type": "Dropdown",
      "choices": [
        { "name": "low", "value": "20" },
        { "name": "medium", "value": "50" },
        { "name": "height", "value": "100" }
      ],
      "binding": {
        "type": "property",
        "name": "camunda:priority"
      }
    }
  ]
}

[pinussilvestrus]

Moving this to backlog as it was not picked for the next iteration. Feel free to disagree.

[christian-konrad]

Hi, a forum user just ran into this issue, too:

https://forum.camunda.io/t/help-use-expression-in-element-templates/39039

The problem became visible earlier as I thought. Since now at least two users reported this and the feature will become more powerful if we fix this, please put it into ready and pick it up on the next planning.

[nikku]

Also reported from the connectors side of things: https://github.com/camunda/web-modeler/issues/3075.

Moving back to ready and hoping to be able to pick this up.

[smbea]

I had a look at this and here are my discoveries:

Regarding rendering without a default values:

• This was fixed with fix(cloud-templates): allow adding properties without default value bpmn-io/bpmn-js-properties-panel#763 and included in Modeler 5.4.0
• However on the template @christian-konrad shows, it will default to "Reset" and not empty because "Reset" has ""/empty as value

Regarding switching between values:

• When: This happens when both dependant options have the same binding even though they have different conditions.

• Why: This is because we reuse a helper function (findOldProperty) to compare a property against a template that is used in ChangeElementTemplateHandler. And the use case is not the same: ChangeElementTemplateHandler cares about maintaining/reusing XML properties, finding a property that fits fulfils that binding and doesn't compare the property label, for example.

EDIT: updated root cause here bpmn-io/bpmn-js-properties-panel#815

[nikku]

Closed via dependency bump.

[nikku]

[igpetrov]

UPD, TLDR: initial dynamic value is not pre-populated.

Hi @nikku, sorry for re-opening, just wanted to double-check if this is released (or is it even the same issue?) because this is an issue raised by one of external users.

I currently still see an issue on dev. Consider following element template and video attached.

{
  "$schema": "https://unpkg.com/@camunda/zeebe-element-templates-json-schema/resources/schema.json",
  "name": "dynamic-values",
  "id": "2b9dc4da-6acc-478c-a774-ece1b04ff988",
  "appliesTo": [
    "bpmn:ServiceTask"
  ],
  "properties": [
    {
      "id": "default-changer",
      "label": "Change the default",
      "type": "Dropdown",
      "choices": [
        {
          "name": "Set it as 1",
          "value": "set-1"
        },
        {
          "name": "Set it as 2",
          "value": "set-2"
        },
        {
          "name": "Set it as 3",
          "value": "set-3"
        }
      ],
      "binding": {
        "type": "zeebe:input",
        "name": "ignore"
      },
      "constraints": {
        "notEmpty": true
      }
    },
    {
      "label": "Test",
      "type": "String",
      "value": "1",
      "binding": {
        "type": "zeebe:input",
        "name": "test"
      },
      "condition": {
        "property": "default-changer",
        "equals": "set-1"
      }
    },
    {
      "label": "Test",
      "type": "String",
      "value": "2",
      "binding": {
        "type": "zeebe:input",
        "name": "test"
      },
      "condition": {
        "property": "default-changer",
        "equals": "set-2"
      }
    },
    {
      "label": "Test",
      "type": "String",
      "value": "3",
      "binding": {
        "type": "zeebe:input",
        "name": "test"
      },
      "condition": {
        "property": "default-changer",
        "equals": "set-3"
      }
    }
  ]
}

Screen.Recording.2022-11-30.at.18.45.50.mov

[nikku]

Thanks for raising. I propose to (and will) move this to a separate issue.

[nikku]

Opened #3327 to track the bug you reported as a follow up.

[nikku]

FYI @igpetrov #3327 (comment).