eclipse-syson · jerome-obeo · Aug 28, 2026
diff --git a/CHANGELOG.adoc b/CHANGELOG.adoc
@@ -114,6 +114,7 @@ The edge goes from the derived requirement to the original one and is displayed
 - https://github.com/eclipse-syson/syson/issues/2428[#2428] [diagrams] Add the _New Derived Requirement_ edge tool on `RequirementUsage` graphical nodes, creating a requirement derivation towards another `RequirementUsage`.
 The edge is drawn from the derived requirement to the original one, and the created derivation has the same shape as one written in text: a `ConnectionUsage` annotated with `#derivation`, whose ends are annotated with `#original` and `#derive`.
 The import of the `RequirementDerivation` library is added to the owning namespace when it is missing.
+- https://github.com/eclipse-syson/syson/issues/2470[#2470] [diagrams] Add the selection of an existing element in `New ItemDefinition as Payload` and `New PartDefinition as Payload` tools on `AcceptAction` graphical node.
 
 == v20
 == v2026.7.0

diff --git a/...syson/application/controllers/diagrams/general/view/GVSubNodeActionFlowCreationTests.java b/...syson/application/controllers/diagrams/general/view/GVSubNodeActionFlowCreationTests.java
@@ -128,9 +128,11 @@ public class GVSubNodeActionFlowCreationTests extends AbstractIntegrationTests {
 
     private static Stream<Arguments> acceptActionUsagePayloadParameters() {
         return Stream.of(
-                Arguments.of(SysmlPackage.eINSTANCE.getPartDefinition()),
-                Arguments.of(SysmlPackage.eINSTANCE.getItemDefinition()))
-                .map(TestNameGenerator::namedArguments);
+                Arguments.of(SysmlPackage.eINSTANCE.getPartDefinition(), ""),
+                Arguments.of(SysmlPackage.eINSTANCE.getPartDefinition(), GeneralViewWithTopNodesTestProjectData.SemanticIds.PART_DEFINITION_ID),
+                Arguments.of(SysmlPackage.eINSTANCE.getItemDefinition(), ""),
+                Arguments.of(SysmlPackage.eINSTANCE.getItemDefinition(), GeneralViewWithTopNodesTestProjectData.SemanticIds.ITEM_DEFINITION_ID)
+        );
     }
 
     private static Stream<Arguments> actionUsageSiblingNodeParameters() {
@@ -223,9 +225,19 @@ public void setUp() {
     @GivenSysONServer({ GeneralViewWithTopNodesTestProjectData.SCRIPT_PATH })
     @ParameterizedTest
     @MethodSource("acceptActionUsagePayloadParameters")
-    public void createAcceptActionUsagePayload(EClass eClass) {
+    public void createAcceptActionUsagePayload(EClass eClass, String selectedNodeId) {
         var flux = this.givenSubscriptionToDiagram();
 
+        AtomicReference<String> expectedPayloadTypeName = new AtomicReference<>();
+        ISemanticChecker initialSemanticChecker = (editingContext) -> {
+            expectedPayloadTypeName.set(this.objectSearchService.getObject(editingContext, selectedNodeId)
+                    .filter(Element.class::isInstance)
+                    .map(Element.class::cast)
+                    .map(Element::getDeclaredName)
+                    .orElse("acceptActionPayloadType"));
+        };
+        Runnable initialSemanticCheck = this.semanticCheckerService.checkEditingContext(initialSemanticChecker);
+
         AtomicReference<Diagram> diagram = new AtomicReference<>();
         Consumer<Object> initialDiagramContentConsumer = assertRefreshedDiagramThat(diagram::set);
 
@@ -236,8 +248,8 @@ public void createAcceptActionUsagePayload(EClass eClass) {
         EClass parentEClass = SysmlPackage.eINSTANCE.getAcceptActionUsage();
         String targetObjectId = GeneralViewWithTopNodesTestProjectData.SemanticIds.ACCEPT_ACTION_USAGE_ID;
 
-        Runnable createNodeRunnable = this.creationTestsService.createNode(diagramDescriptionIdProvider, diagram, parentEClass, targetObjectId,
-                this.descriptionNameGenerator.getCreationToolName("New {0} as Payload", eClass));
+        Runnable createNodeRunnable = this.creationTestsService.createNodeWithSelectionDialogWithSingleSelection(diagramDescriptionIdProvider, diagram, parentEClass, targetObjectId,
+                this.descriptionNameGenerator.getCreationToolName("New {0} as Payload", eClass), selectedNodeId);
 
         Consumer<Object> diagramCheck = assertRefreshedDiagramThat(newDiagram -> {
             new CheckDiagramElementCount(this.diagramComparator)
@@ -251,7 +263,7 @@ public void createAcceptActionUsagePayload(EClass eClass) {
             assertThat(updatedNode.getInsideLabel()).as("The updated node label should exist").isNotNull();
             assertThat(updatedNode.getInsideLabel().getText())
                     .contains(LabelConstants.OPEN_QUOTE + "accept" + LabelConstants.CLOSE_QUOTE)
-                    .contains("payload: acceptActionPayloadType");
+                    .contains("payload: " + expectedPayloadTypeName.get());
         });
 
         ISemanticChecker semanticChecker = (editingContext) -> {
@@ -269,13 +281,14 @@ public void createAcceptActionUsagePayload(EClass eClass) {
             assertThat(relationship).isInstanceOf(FeatureTyping.class);
             FeatureTyping featureTyping = (FeatureTyping) relationship;
             assertThat(eClass.isInstance(featureTyping.getType()));
-            assertThat(featureTyping.getType().getName()).isEqualTo("acceptActionPayloadType");
+            assertThat(featureTyping.getType().getName()).isEqualTo(expectedPayloadTypeName.get());
         };
 
         Runnable semanticCheck = this.semanticCheckerService.checkEditingContext(semanticChecker);
 
         StepVerifier.create(flux)
                 .consumeNextWith(initialDiagramContentConsumer)
+                .then(initialSemanticCheck)
                 .then(createNodeRunnable)
                 .consumeNextWith(diagramCheck)
                 .then(semanticCheck)

diff --git a/...services/src/main/java/org/eclipse/syson/diagram/services/DiagramMutationToolService.java b/...services/src/main/java/org/eclipse/syson/diagram/services/DiagramMutationToolService.java
@@ -16,6 +16,7 @@
 import java.util.ArrayList;
 import java.util.List;
 import java.util.Objects;
+import java.util.Optional;
 
 import org.apache.commons.lang3.StringUtils;
 import org.eclipse.emf.ecore.EClass;
@@ -596,38 +597,51 @@ public Element createAcceptAction(Element ownerElement) {
      * Create or replace the payload parameter of an accept action usage.
      *
      * @param self
-     *            the accept action usage
+     *         the accept action usage
      * @param payloadEClassName
-     *            the payload classifier name
+     *         the payload classifier name
+     * @param selectedObject
+     *         the payload classifier given by the selection dialog
      * @return the given accept action usage
      */
-    public Element createAcceptActionPayload(AcceptActionUsage self, String payloadEClassName) {
+    public Element createAcceptActionPayload(AcceptActionUsage self, String payloadEClassName, Element selectedObject) {
+        var payloadType = Optional.ofNullable(selectedObject)
+                .filter(Type.class::isInstance)
+                .map(Type.class::cast)
+                .orElse(this.createNewAcceptActionPayload(payloadEClassName, self));
+        if (payloadType != null) {
+            var featureTyping = SysmlFactory.eINSTANCE.createFeatureTyping();
+            featureTyping.setType(payloadType);
+            var referenceUsage = SysmlFactory.eINSTANCE.createReferenceUsage();
+            referenceUsage.setDeclaredName("payload");
+            referenceUsage.setDirection(FeatureDirectionKind.INOUT);
+            referenceUsage.getOwnedRelationship().add(featureTyping);
+            var parameterMembership = this.getPayloadParameterMembership(self);
+            var oldParameterContent = parameterMembership.getOwnedMemberParameter();
+            if (oldParameterContent != null) {
+                this.deleteService.deleteFromModel(oldParameterContent);
+            }
+            parameterMembership = this.getPayloadParameterMembership(self);
+            parameterMembership.getOwnedRelatedElement().add(referenceUsage);
+            self.getOwnedRelationship().add(parameterMembership);
+        }
+        return self;
+    }
+
+    private Type createNewAcceptActionPayload(String payloadEClassName, AcceptActionUsage acceptActionName) {
         var classifier = SysmlPackage.eINSTANCE.getEClassifier(payloadEClassName);
         if (classifier instanceof EClass eClass) {
             var payload = SysmlFactory.eINSTANCE.create(eClass);
             if (payload instanceof Type payloadType) {
-                payloadType.setDeclaredName(self.getDeclaredName() + "PayloadType");
+                payloadType.setDeclaredName(acceptActionName.getDeclaredName() + "PayloadType");
                 var membership = SysmlFactory.eINSTANCE.createOwningMembership();
                 membership.getOwnedRelatedElement().add(payloadType);
-                var payloadParent = this.getClosestContainingPackageFrom(self);
+                var payloadParent = this.getClosestContainingPackageFrom(acceptActionName);
                 payloadParent.getOwnedRelationship().add(membership);
-                var featureTyping = SysmlFactory.eINSTANCE.createFeatureTyping();
-                featureTyping.setType(payloadType);
-                var referenceUsage = SysmlFactory.eINSTANCE.createReferenceUsage();
-                referenceUsage.setDeclaredName("payload");
-                referenceUsage.setDirection(FeatureDirectionKind.INOUT);
-                referenceUsage.getOwnedRelationship().add(featureTyping);
-                var parameterMembership = this.getPayloadParameterMembership(self);
-                var oldParameterContent = parameterMembership.getOwnedMemberParameter();
-                if (oldParameterContent != null) {
-                    this.deleteService.deleteFromModel(oldParameterContent);
-                }
-                parameterMembership = this.getPayloadParameterMembership(self);
-                parameterMembership.getOwnedRelatedElement().add(referenceUsage);
-                self.getOwnedRelationship().add(parameterMembership);
+                return payloadType;
             }
         }
-        return self;
+        return null;
     }
 
     /**

diff --git a/...vices/src/main/java/org/eclipse/syson/diagram/services/aql/DiagramMutationAQLService.java b/...vices/src/main/java/org/eclipse/syson/diagram/services/aql/DiagramMutationAQLService.java
@@ -144,10 +144,10 @@ public Element createAcceptAction(Element ownerElement) {
     }
 
     /**
-     * {@link DiagramMutationToolService#createAcceptActionPayload(AcceptActionUsage, String)}.
+     * {@link DiagramMutationToolService#createAcceptActionPayload(AcceptActionUsage, String, Element)}.
      */
-    public Element createAcceptActionPayload(AcceptActionUsage self, String payloadEClassName) {
-        return this.diagramMutationToolService.createAcceptActionPayload(self, payloadEClassName);
+    public Element createAcceptActionPayload(AcceptActionUsage self, String payloadEClassName, Element selectedObject) {
+        return this.diagramMutationToolService.createAcceptActionPayload(self, payloadEClassName, selectedObject);
     }
 
     /**

diff --git a/...java/org/eclipse/syson/diagram/common/view/tools/AcceptActionPayloadNodeToolProvider.java b/...java/org/eclipse/syson/diagram/common/view/tools/AcceptActionPayloadNodeToolProvider.java
@@ -1,5 +1,5 @@
 /*******************************************************************************
- * Copyright (c) 2024 Obeo.
+ * Copyright (c) 2026 Obeo.
  * This program and the accompanying materials
  * are made available under the terms of the Eclipse Public License v2.0
  * which accompanies this distribution, and is available at
@@ -12,16 +12,25 @@
  *******************************************************************************/
 package org.eclipse.syson.diagram.common.view.tools;
 
+import java.util.List;
 import java.util.Objects;
 
 import org.eclipse.emf.ecore.EClass;
+import org.eclipse.sirius.components.core.api.IEditingContext;
+import org.eclipse.sirius.components.trees.renderer.TreeRenderer;
 import org.eclipse.sirius.components.view.builder.IViewDiagramElementFinder;
 import org.eclipse.sirius.components.view.builder.generated.diagram.DiagramBuilders;
 import org.eclipse.sirius.components.view.builder.generated.view.ViewBuilders;
 import org.eclipse.sirius.components.view.builder.providers.INodeToolProvider;
+import org.eclipse.sirius.components.view.diagram.DialogDescription;
 import org.eclipse.sirius.components.view.diagram.NodeTool;
+import org.eclipse.syson.diagram.services.aql.DiagramMutationAQLService;
+import org.eclipse.syson.tree.services.aql.TreeQueryAQLService;
 import org.eclipse.syson.util.AQLConstants;
+import org.eclipse.syson.util.AQLUtils;
 import org.eclipse.syson.util.IDescriptionNameGenerator;
+import org.eclipse.syson.util.ServiceMethod;
+import org.eclipse.syson.util.SysMLMetamodelHelper;
 
 /**
  * Used to create element as a payload of an accept action usage.
@@ -48,7 +57,7 @@ public NodeTool create(IViewDiagramElementFinder cache) {
         var builder = this.diagramBuilderHelper.newNodeTool();
 
         var creationPayloadServiceCall = this.viewBuilderHelper.newChangeContext()
-                .expression(AQLConstants.AQL_SELF + ".createAcceptActionPayload('" + this.payloadEClass.getName() + "')")
+                .expression(ServiceMethod.of2(DiagramMutationAQLService::createAcceptActionPayload).aqlSelf(AQLUtils.aqlString(this.payloadEClass.getName()), "selectedObject"))
                 .build();
 
         var rootChangContext = this.viewBuilderHelper.newChangeContext()
@@ -60,6 +69,31 @@ public NodeTool create(IViewDiagramElementFinder cache) {
                 .iconURLsExpression("/icons/full/obj16/" + this.payloadEClass.getName() + ".svg")
                 .body(rootChangContext)
                 .preconditionExpression(AQLConstants.AQL_SELF + ".isEmptyAcceptActionUsagePayload()")
+                .dialogDescription(this.getSelectionDialogDescription())
+                .build();
+    }
+
+    private DialogDescription getSelectionDialogDescription() {
+        var payloadTypeName = SysMLMetamodelHelper.buildQualifiedName(this.payloadEClass);
+        var selectionDialogTree = this.diagramBuilderHelper.newSelectionDialogTreeDescription()
+                .elementsExpression(ServiceMethod.of1(TreeQueryAQLService::getSelectionDialogElements).aql(IEditingContext.EDITING_CONTEXT, AQLUtils.aqlSequence(List.of(payloadTypeName))))
+                .childrenExpression(
+                        ServiceMethod.of3(TreeQueryAQLService::getSelectionDialogChildren).aqlSelf(IEditingContext.EDITING_CONTEXT, TreeRenderer.EXPANDED, AQLUtils.aqlSequence(List.of(payloadTypeName))))
+                .isSelectableExpression(AQLConstants.AQL_SELF + ".oclIsKindOf(" + payloadTypeName + ")")
+                .build();
+        String payloadName = this.payloadEClass.getName();
+        return this.diagramBuilderHelper.newSelectionDialogDescription()
+                .selectionDialogTreeDescription(selectionDialogTree)
+                .defaultTitleExpression("Set payload")
+                .descriptionExpression(payloadName + " as payload")
+                .noSelectionActionLabelExpression("Create a New " + payloadName)
+                .noSelectionActionDescriptionExpression("Set the payload with a New " + payloadName)
+                .withSelectionActionLabelExpression("Select an existing " + payloadName)
+                .withSelectionActionDescriptionExpression("Set the payload with an existing " + payloadName)
+                .noSelectionActionStatusMessageExpression("It will set the payload with a New " + payloadName)
+                .selectionRequiredWithoutSelectionStatusMessageExpression("Select one " + payloadName)
+                .selectionRequiredWithSelectionStatusMessageExpression(AQLConstants.AQL + "'It will set the payload with ' + selectedObjects->first().name")
+                .optional(true)
                 .build();
     }
 }
diff --git a/doc/content/modules/user-manual/pages/release-notes/2026.9.0.adoc b/doc/content/modules/user-manual/pages/release-notes/2026.9.0.adoc
@@ -98,6 +98,7 @@ image::release-notes-port-inherited-item-border-nodes.png[ItemUsage border node
 
 ** Improve the edge tool creating a `FlowUsage`, by creating a `ReferenceUsage` used for the redefinition of the `FlowEnd` only when it is needed.
 ** Fix the edge tool creating a `ConnectionUsage` between an `ActionUsage` graphical node and the _done_ `ActionUsage` graphical node.
+** Add the capability of selecting an existing element in `New ItemDefinition as Payload` and `New PartDefinition as Payload` tools on `AcceptAction` graphical node. The creation a new element remains available.
 
 == Bug fixes