Fixes Bug in MongoDBStorage with Entity in Entities

basyx.submodelservice/basyx.submodelservice-backend-mongodb/src/main/java/org/eclipse/digitaltwin/basyx/submodelservice/backend/MongoDbSubmodelOperations.java

@@ -193,7 +193,8 @@ public void createSubmodelElement(String submodelId, String idShortPath, Submode
 
     @Override
     public void updateSubmodelElement(String submodelId, String idShortPath, SubmodelElement submodelElement) throws ElementDoesNotExistException {
-        MongoFilterResult filterResult = MongoFilterBuilder.parse(idShortPath);
+        List<SubmodelElement> parentElements = getParentElements(submodelId, idShortPath);
+        MongoFilterResult filterResult = MongoFilterBuilder.parse(idShortPath, parentElements);
 
         Query query = new Query(Criteria.where("_id").is(submodelId));
         Update update = new Update().set(filterResult.key(), submodelElement);
@@ -326,6 +327,36 @@ private boolean existsSubmodelElement(String submodelId, String idShortPath){
         }
     }
 
+    /**
+     * Gets the list of parent SubmodelElements along the path.
+     * This is used to determine if any parent is an Entity (which uses 'statements' instead of 'value').
+     */
+    private List<SubmodelElement> getParentElements(String submodelId, String idShortPath) {
+        List<SubmodelElement> parents = new ArrayList<>();
+        String[] segments = idShortPath.split("\\.");
+
+        if (segments.length <= 1) {
+            return parents;
+        }
+
+        StringBuilder currentPath = new StringBuilder();
+        for (int i = 0; i < segments.length - 1; i++) {
+            if (currentPath.length() > 0) {
+                currentPath.append(".");
+            }
+            currentPath.append(segments[i]);
+            try {
+                SubmodelElement element = getSubmodelElement(submodelId, currentPath.toString());
+                parents.add(element);
+            } catch (ElementDoesNotExistException e) {
+                // Element doesn't exist, stop here
+                break;
+            }
+        }
+
+        return parents;
+    }
+
     private static boolean hasLimit(PaginationInfo pInfo) {
         return pInfo.getLimit() != null && pInfo.getLimit() > 0;
     }

basyx.submodelservice/basyx.submodelservice-backend-mongodb/src/main/java/org/eclipse/digitaltwin/basyx/submodelservice/backend/MongoFilterBuilder.java

@@ -29,6 +29,8 @@
 import java.util.Deque;
 import java.util.List;
 
+import org.eclipse.digitaltwin.aas4j.v3.model.Entity;
+import org.eclipse.digitaltwin.aas4j.v3.model.SubmodelElement;
 import org.eclipse.digitaltwin.basyx.submodelservice.backend.IdShortPathParser.GenericPath;
 import org.eclipse.digitaltwin.basyx.submodelservice.backend.IdShortPathParser.IdShortPath;
 import org.eclipse.digitaltwin.basyx.submodelservice.backend.IdShortPathParser.IndexPath;
@@ -54,13 +56,25 @@ public final class MongoFilterBuilder{
     static final String KEY_ID_SHORT = "idShort";
 
     public static MongoFilterResult parse(@NonNull String idShortPath) {
+        return parse(idShortPath, List.of());
+    }
+
+    /**
+     * Parses the idShortPath and builds MongoDB filter result.
+     * 
+     * @param idShortPath the path to parse
+     * @param parentElements list of parent SubmodelElements along the path (used to determine if Entity uses 'statements')
+     * @return MongoFilterResult with the update key and filters
+     */
+    public static MongoFilterResult parse(@NonNull String idShortPath, @NonNull List<SubmodelElement> parentElements) {
         Deque<GenericPath> paths = IdShortPathParser.parse(idShortPath);
 
         assert !paths.isEmpty();
 
         StringBuilder updateKey = new StringBuilder();
         List<CriteriaDefinition> filterArray = new ArrayList<>();
         int filterCounter = 0;
+        int parentIndex = 0;
 
         updateKey.append(KEY_SUBMODEL_ELEMENTS);
 
@@ -74,7 +88,14 @@ public static MongoFilterResult parse(@NonNull String idShortPath) {
 
         while (!paths.isEmpty()) {
             GenericPath segment = paths.pop();
-            updateKey.append(".").append(KEY_VALUE);
+            // Determine whether to use 'statements' (for Entity) or 'value' (for others)
+            String childKey = KEY_VALUE;
+            if (parentIndex < parentElements.size() && parentElements.get(parentIndex) instanceof Entity) {
+                childKey = KEY_STATEMENTS;
+            }
+            updateKey.append(".").append(childKey);
+            parentIndex++;
+
             if (segment instanceof IdShortPath idPath) {
                 placeholder = "elem" + filterCounter++;
                 updateKey.append(".$[").append(placeholder).append("]");

basyx.submodelservice/basyx.submodelservice-core/src/test/java/org/eclipse/digitaltwin/basyx/submodelservice/SubmodelServiceSuite.java

@@ -670,6 +670,25 @@ public void patchSubmodelElements() {
 		assertEquals(submodelElementsPatch, patchedSubmodel.getSubmodelElements());
 	}
 
+	@Test
+	public void addEntityToEntity() {
+		List<SubmodelElement> submodelElements = new ArrayList<>();
+		Entity entity = new DefaultEntity.Builder().idShort("MainEntity").build();
+		submodelElements.add(entity);
+		Submodel submodel = buildDummySubmodelWithSmElement(ID, submodelElements);
+		SubmodelService submodelService = getSubmodelService(submodel);
+
+		Entity subEntity = new DefaultEntity.Builder().idShort("SubEntity").build();
+		submodelService.createSubmodelElement("MainEntity", subEntity);
+
+
+		Entity sub_subEntity = new DefaultEntity.Builder().idShort("Sub_SubEntity").build();
+		submodelService.createSubmodelElement("MainEntity.SubEntity", sub_subEntity);
+
+		SubmodelElement sme = submodelService.getSubmodelElement("MainEntity.SubEntity.Sub_SubEntity");
+		assertEquals(sub_subEntity.getIdShort(), sme.getIdShort());
+	}
+
 	protected Submodel buildDummySubmodelWithSmElement(String id, List<SubmodelElement> submodelElements) {
 		return new DefaultSubmodel.Builder().id(id).submodelElements(submodelElements).build();
 	}