fix: create new user task form only if user task form referenced

Related to camunda/camunda-modeler#4658

lib/camunda-cloud/FormsBehavior.js

@@ -5,13 +5,11 @@ import CommandInterceptor from 'diagram-js/lib/command/CommandInterceptor';
 import { createElement } from '../util/ElementUtil';
 import { getExtensionElementsList } from '../util/ExtensionElementsUtil';
 
-import {
-  getBusinessObject,
-  is
-} from 'bpmn-js/lib/util/ModelUtil';
+import { is } from 'bpmn-js/lib/util/ModelUtil';
 
 import {
   createUserTaskFormId,
+  formKeyToUserTaskFormId,
   getFormDefinition,
   getRootElement,
   getUserTaskForm,
@@ -24,7 +22,7 @@ import {
  * Zeebe BPMN specific forms behavior.
  */
 export default class FormsBehavior extends CommandInterceptor {
-  constructor(bpmnFactory, eventBus, modeling) {
+  constructor(bpmnFactory, elementRegistry, eventBus, modeling) {
     super(eventBus);
 
     this._modeling = modeling;
@@ -67,67 +65,79 @@ export default class FormsBehavior extends CommandInterceptor {
 
 
     /**
-     * Create new zeebe:FormDefinition and zeebe:UserTaskForm on user task created.
+     * Create and reference new zeebe:UserTaskForm when user task is created
+     * that references existing zeebe:UserTaskForm that is already referenced by
+     * existing user task.
      */
     this.postExecute('shape.create', function(context) {
       const { shape } = context;
 
+      if (!is(shape, 'bpmn:UserTask')) {
+        return;
+      }
+
       const oldFormDefinition = getFormDefinition(shape);
 
-      if (!is(shape, 'bpmn:UserTask') || !oldFormDefinition) {
+      if (!oldFormDefinition) {
         return;
       }
 
       const oldUserTaskForm = getUserTaskForm(shape);
 
-      const rootElement = getRootElement(shape);
-
-      const businessObject = getBusinessObject(shape);
+      if (!oldUserTaskForm) {
+        return;
+      }
 
-      const extensionElements = businessObject.get('extensionElements');
+      const isReferenced = elementRegistry.filter(element => {
+        if (element === shape) {
+          return false;
+        }
 
-      let rootExtensionElements = rootElement.get('extensionElements');
+        const formDefinition = getFormDefinition(element);
 
-      // (1) ensure extension elements exists
-      if (!rootExtensionElements) {
-        rootExtensionElements = createElement('bpmn:ExtensionElements', { values: [] }, rootElement, bpmnFactory);
+        return formDefinition
+          && formDefinition.get('formKey')
+          && formKeyToUserTaskFormId(formDefinition.get('formKey')) === oldUserTaskForm.get('id');
+      });
 
-        modeling.updateModdleProperties(shape, rootElement, { extensionElements: rootExtensionElements });
+      if (!isReferenced.length) {
+        return;
       }
 
-      // (2) remove existing form definition
-      let values = extensionElements.get('values').filter((element) => {
-        return element !== oldFormDefinition;
-      });
+      const rootElement = getRootElement(shape);
 
-      // (3) create new form definition
-      const userTaskFormId = createUserTaskFormId();
+      let extensionElements = rootElement.get('extensionElements');
 
-      const newFormDefinition = createElement('zeebe:FormDefinition', {
-        formKey: userTaskFormIdToFormKey(userTaskFormId)
-      }, extensionElements, bpmnFactory);
+      // (1) ensure extension elements exist
+      if (!extensionElements) {
+        extensionElements = createElement('bpmn:ExtensionElements', {
+          values: []
+        }, rootElement, bpmnFactory);
 
-      values = [
-        ...values,
-        newFormDefinition
-      ];
+        modeling.updateModdleProperties(shape, rootElement, {
+          extensionElements
+        });
+      }
 
-      modeling.updateModdleProperties(shape, extensionElements, {
-        values
-      });
+      // (2) create new user task form
+      const userTaskFormId = createUserTaskFormId();
 
-      // (4) create new user task form
       const userTaskForm = createElement('zeebe:UserTaskForm', {
         id: userTaskFormId,
-        body: oldUserTaskForm ? oldUserTaskForm.get('body') : ''
-      }, rootExtensionElements, bpmnFactory);
+        body: oldUserTaskForm.get('body')
+      }, extensionElements, bpmnFactory);
 
-      modeling.updateModdleProperties(shape, rootExtensionElements, {
+      modeling.updateModdleProperties(shape, extensionElements, {
         values: [
-          ...(rootExtensionElements.get('values') || []),
+          ...(extensionElements.get('values') || []),
           userTaskForm
         ]
       });
+
+      // (3) reference new user task form
+      modeling.updateModdleProperties(shape, oldFormDefinition, {
+        formKey: userTaskFormIdToFormKey(userTaskFormId)
+      });
     }, true);
 
 
@@ -277,6 +287,7 @@ export default class FormsBehavior extends CommandInterceptor {
 
 FormsBehavior.$inject = [
   'bpmnFactory',
+  'elementRegistry',
   'eventBus',
   'modeling'
 ];