feat: support `bpmn:ConditionalEventDefinition` templates by jarekdanielak · Pull Request #217 · bpmn-io/bpmn-js-element-templates

jarekdanielak · 2026-02-02T13:26:58Z

Related to camunda/camunda-modeler#5400

Proposed Changes

Support templating for bpmn:ConditionalEventDefinition:

Template condition via bpmn:ConditionalEventDefinition#property binding.
Template variableNames and variableEvents via bpmn:ConditionalEventDefinition#zeebe:conditionalFilter#property binding.
Add ConditionalEventTemplateBehavior to ensure a template variableEvents binding is not applied to a root-level event.

Try it

npm start this project and use "Conditional Event" or your own template.

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jarekdanielak · 2026-02-02T13:27:15Z

Waiting for bpmn-io/bpmn-js-properties-panel#1176 to test this E2E

jarekdanielak · 2026-02-03T11:57:37Z

src/cloud-element-templates/cmd/ChangeElementTemplateHandler.js

+        // Handle zeebe:conditionalFilter properties (variableNames, variableEvents)
+        let conditionalFilter = findExtension(conditionalEventDefinition, 'zeebe:ConditionalFilter');
+
+        if (oldProperty && shouldKeepValue(conditionalEventDefinition, oldProperty, newProperty)) {


This is worrisome, I don't think shouldKeepValue holds to what it promises in its docs. I won't change it in this PR, since it's used in many places, but I'm looking into it for an Hour of Code session.

Copilot

Pull request overview

This pull request adds support for templating bpmn:ConditionalEventDefinition elements in BPMN diagrams. The implementation allows users to create element templates that can configure conditional events through two new binding types.

Changes:

Added support for bpmn:ConditionalEventDefinition#property binding to template condition expressions
Added support for bpmn:ConditionalEventDefinition#zeebe:conditionalFilter#property binding to template variableNames and variableEvents properties
Introduced ConditionalEventTemplateBehavior to automatically unlink templates with variableEvents binding when applied to root-level events (where they are not supported)
Fixed version 0 handling in template validation to correctly distinguish between templates without a version and templates with version 0
Updated dependencies including bpmn-moddle to v10.0.0, which includes breaking changes (renamed BPMNModdle export to BpmnModdle)

Reviewed changes

Copilot reviewed 16 out of 17 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
src/cloud-element-templates/Helper.js	Added `findConditionalEventDefinition` helper function
src/cloud-element-templates/util/bindingTypes.js	Added two new binding type constants for conditional events
src/cloud-element-templates/util/propertyUtil.js	Implemented get/set logic for conditional event bindings
src/cloud-element-templates/cmd/ChangeElementTemplateHandler.js	Added `_updateConditionalEventDefinition` method and supporting functions
src/cloud-element-templates/behavior/ConditionalEventTemplateBehavior.js	New behavior to enforce constraints on conditional event templates
src/cloud-element-templates/behavior/index.js	Registered new behavior in module exports
src/element-templates/Validator.js	Fixed version 0 handling using `isNil()` instead of falsy check
src/cloud-element-templates/Validator.js	Fixed version 0 handling using `isNil()` instead of falsy check
test files	Comprehensive test coverage for all new functionality
package.json	Updated dependencies including major version bump for bpmn-moddle
CHANGELOG.md	Added FIX entry for version 0 handling (missing FEAT entry)

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Pull request overview

Copilot reviewed 16 out of 17 changed files in this pull request and generated 3 comments.

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Copilot · 2026-02-04T15:25:50Z

test/spec/cloud-element-templates/behavior/ConditionalEventTemplateBehavior.spec.js

+  describe('apply template', function() {
+
+    it('should unlink template with variableEvents on root-level', inject(
+      function(elementRegistry, elementTemplates) {
+
+        // given
+        let event = elementRegistry.get('RootEvent');
+
+        // when
+        event = elementTemplates.applyTemplate(event, templates[0]);
+
+        // then
+        expect(getBusinessObject(event).get('zeebe:modelerTemplate')).not.to.exist;
+      }
+    ));
+
+
+    it('should keep template without variableEvents on root-level', inject(
+      function(elementRegistry, elementTemplates) {
+
+        // given
+        let event = elementRegistry.get('RootEvent');
+
+        // when
+        event = elementTemplates.applyTemplate(event, templates[1]);
+
+        // then
+        expect(getBusinessObject(event).get('zeebe:modelerTemplate')).to.equal('conditional-no-variable-events-template');
+      }
+    ));
+
+
+    it('should keep template without variableEvents in subprocess', inject(
+      function(elementRegistry, elementTemplates) {
+
+        // given
+        let event = elementRegistry.get('Subprocess_Event');
+
+        // when
+        event = elementTemplates.applyTemplate(event, templates[1]);
+
+        // then
+        expect(getBusinessObject(event).get('zeebe:modelerTemplate')).to.equal('conditional-no-variable-events-template');
+      }
+    ));
+  });


Missing test case: there should be a test that verifies templates with variableEvents can be successfully applied to events within subprocesses (not just root-level). This would test the positive case where the template should be kept, complementing the test on line 42 that verifies templates with variableEvents are correctly rejected at root-level.

Copilot · 2026-02-04T15:25:50Z

test/spec/cloud-element-templates/properties/CustomProperties.spec.js


    function openTooltip(element) {
      return act(() => {
        fireEvent.mouseEnter(element);


The timeout value was changed from 200ms to 250ms, but there's no explanation for this change in the PR description. If this is related to the dependency updates (bpmn-js-properties-panel upgrade from 5.42.0 to 5.49.0), it should be documented. Otherwise, if this change is unrelated to the conditional event feature, it should be in a separate commit or PR.

Suggested change

fireEvent.mouseEnter(element);

fireEvent.mouseEnter(element);

// 250ms matches the tooltip show delay in the properties panel implementation.

Copilot · 2026-02-04T15:25:50Z

src/cloud-element-templates/cmd/ChangeElementTemplateHandler.js

+    return businessObject.get(bindingName)?.get('body');
+  }
+
+  if (bindingType === CONDITIONAL_EVENT_DEFINITION_ZEEBE_CONDITIONAL_FILTER_PROPERTY) {
+    const conditionalFilter = findExtension(businessObject, 'zeebe:ConditionalFilter');


The getPropertyValue function is looking for conditional event properties in the wrong location. It should use findConditionalEventDefinition to get the conditional event definition first, similar to how the timer event definition properties are handled on lines 2427-2431. Currently, it's trying to access properties directly from the element's businessObject, which will not work because the condition and conditionalFilter are properties of the ConditionalEventDefinition, not the element itself.

Suggested change

return businessObject.get(bindingName)?.get('body');

}

if (bindingType === CONDITIONAL_EVENT_DEFINITION_ZEEBE_CONDITIONAL_FILTER_PROPERTY) {

const conditionalFilter = findExtension(businessObject, 'zeebe:ConditionalFilter');

const conditionalEventDefinition = findConditionalEventDefinition(businessObject);

if (!conditionalEventDefinition) {

return;

}

// the actual value is nested in an Expression on the ConditionalEventDefinition

return conditionalEventDefinition.get(bindingName)?.get('body');

}

if (bindingType === CONDITIONAL_EVENT_DEFINITION_ZEEBE_CONDITIONAL_FILTER_PROPERTY) {

const conditionalEventDefinition = findConditionalEventDefinition(businessObject);

if (!conditionalEventDefinition) {

return;

}

const conditionalFilter = findExtension(conditionalEventDefinition, 'zeebe:ConditionalFilter');

Related to camunda/camunda-modeler#5400

jarekdanielak · 2026-02-05T11:39:06Z

Adjusted to correctly handle Intermediate Catch Events and rebased on main.

Ready for review @nikku, @barmac.

philippfromme · 2026-02-06T12:54:40Z

I'm not sure if this is an issue with the demo or not. But creating an element with the template doesn't work:

Applying the template to an existing element works.

I also see this error in the console every time I make a change:

jarekdanielak · 2026-02-06T13:35:38Z

Console error is fixed by bumping @camunda/linting: 0d990d2

For creating elements, looks like I forgot to update the element factory... 🤦‍♂️ Done in 0d17f6f

@philippfromme ready for another round.

jarekdanielak self-assigned this Feb 2, 2026

bpmn-io-tasks bot added the in progress Currently worked on label Feb 2, 2026

jarekdanielak mentioned this pull request Feb 2, 2026

Support conditional events modeling camunda/camunda-modeler#5400

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jarekdanielak commented Feb 3, 2026

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jarekdanielak force-pushed the conditional-event branch from 55066c3 to 7e07d1a Compare February 4, 2026 15:10

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jarekdanielak marked this pull request as ready for review February 4, 2026 15:14

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jarekdanielak force-pushed the conditional-event branch 2 times, most recently from bdb0cc6 to a7a5867 Compare February 4, 2026 15:17

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jarekdanielak force-pushed the conditional-event branch from a7a5867 to 2f14b1e Compare February 5, 2026 11:34

feat: support bpmn:ConditionalEventDefinition templates

b2fb0e4

Related to camunda/camunda-modeler#5400

jarekdanielak force-pushed the conditional-event branch from 2f14b1e to 8b804e7 Compare February 5, 2026 11:37

chore: bump bpmn-js-properties-panel

3fb5ee8

jarekdanielak force-pushed the conditional-event branch from 8b804e7 to 3fb5ee8 Compare February 5, 2026 11:40

chore: bump camunda-bpmn-js-behaviors

f18d47f

jarekdanielak added 2 commits February 6, 2026 14:22

chore: bump @camunda/linting

0d990d2

chore: update TemplateElementFactory

0d17f6f

jarekdanielak added 2 commits February 6, 2026 14:52

chore: refactor

387a2f0

test: cover removing conditional event properties

ba8fec3

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feat: support `bpmn:ConditionalEventDefinition` templates#217

feat: support `bpmn:ConditionalEventDefinition` templates#217
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	fireEvent.mouseEnter(element);
	fireEvent.mouseEnter(element);
	// 250ms matches the tooltip show delay in the properties panel implementation.

-    return businessObject.get(bindingName)?.get('body');
-  }
-  if (bindingType === CONDITIONAL_EVENT_DEFINITION_ZEEBE_CONDITIONAL_FILTER_PROPERTY) {
-    const conditionalFilter = findExtension(businessObject, 'zeebe:ConditionalFilter');
+    const conditionalEventDefinition = findConditionalEventDefinition(businessObject);
+    if (!conditionalEventDefinition) {
+      return;
+    }
+    // the actual value is nested in an Expression on the ConditionalEventDefinition
+    return conditionalEventDefinition.get(bindingName)?.get('body');
+  }
+  if (bindingType === CONDITIONAL_EVENT_DEFINITION_ZEEBE_CONDITIONAL_FILTER_PROPERTY) {
+    const conditionalEventDefinition = findConditionalEventDefinition(businessObject);
+    if (!conditionalEventDefinition) {
+      return;
+    }
+    const conditionalFilter = findExtension(conditionalEventDefinition, 'zeebe:ConditionalFilter');

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