Core: Add Gui::Document::getTreeRootObjects()

src/Gui/Document.cpp

@@ -2531,3 +2531,32 @@ void Document::slotChangePropertyEditor(const App::Document &doc, const App::Pro
         getMainWindow()->setUserSchema(doc.UnitSystem.getValue());
     }
 }
+
+std::vector<App::DocumentObject*> Document::getTreeRootObjects() const
+{
+    std::vector<App::DocumentObject*> docObjects = d->_pcDocument->getObjects();
+    std::unordered_map<App::DocumentObject*, bool> rootMap;
+    for (auto it : docObjects) {
+        rootMap[it] = true;
+    }
+
+    for (auto obj : docObjects) {
+        ViewProvider* vp = Application::Instance->getViewProvider(obj);
+        if (!vp) {
+            continue;
+        }
+
+        std::vector<App::DocumentObject*> children = vp->claimChildren();
+        for (auto child : children) {
+            rootMap[child] = false;
+        }
+    }
+
+    std::vector<App::DocumentObject*> rootObjs;
+    for (const auto& it : rootMap) {
+        if (it.second) {
+            rootObjs.push_back(it.first);
+        }
+    }
+    return rootObjs;
+}

src/Gui/Document.h

@@ -298,6 +298,9 @@ public:
     const char *getCameraSettings() const;
     bool saveCameraSettings(const char *) const;
 
+    /// get all tree root objects (objects that are at the root of the object tree)
+    std::vector<App::DocumentObject*> getTreeRootObjects() const;
+
 protected:
     // pointer to the python class
     Gui::DocumentPy *_pcDocPy;

src/Gui/DocumentPy.xml

@@ -243,5 +243,11 @@ obj : Gui.ViewProvider</UserDocu>
       </Documentation>
       <Parameter Name="Modified" Type="Boolean" />
     </Attribute>
+    <Attribute Name="TreeRootObjects" ReadOnly="true">
+      <Documentation>
+        <UserDocu>The list of tree root objects.</UserDocu>
+      </Documentation>
+      <Parameter Name="TreeRootObjects" Type="List" />
+    </Attribute>
   </PythonExport>
 </GenerateModel>

src/Gui/DocumentPyImp.cpp

@@ -509,6 +509,20 @@ void DocumentPy::setModified(Py::Boolean arg)
     getDocumentPtr()->setModified(arg);
 }
 
+Py::List DocumentPy::getTreeRootObjects() const
+{
+    std::vector<App::DocumentObject*> objs = getDocumentPtr()->getTreeRootObjects();
+    Py::List res;
+
+    for (auto obj : objs) {
+        //Note: Here we must force the Py::Object to own this Python object as getPyObject() increments the counter
+        res.append(Py::Object(obj->getPyObject(), true));
+    }
+
+    return res;
+}
+
+
 PyObject *DocumentPy::getCustomAttributes(const char* attr) const
 {
     // Note: Here we want to return only a document object if its

src/Gui/Tree.cpp

@@ -2754,7 +2754,8 @@ void TreeWidget::sortDroppedObjects(TargetItemInfo& targetInfo, std::vector<App:
         propGroup->setValue(sortedObjList);
     }
     else if (targetInfo.targetItem->type() == TreeWidget::DocumentType) {
-        objList = targetInfo.targetDoc->getRootObjectsIgnoreLinks();
+        Gui::Document* guiDoc = Gui::Application::Instance->getDocument(targetInfo.targetDoc->getName());
+        objList = guiDoc->getTreeRootObjects();
         // First we need to sort objList by treeRank.
         std::sort(objList.begin(), objList.end(),
             [](App::DocumentObject* a, App::DocumentObject* b) {

src/Mod/Assembly/CommandInsertLink.py

@@ -203,7 +203,8 @@ class TaskAssemblyInsertLink(QtCore.QObject):
                         ):
                             process_objects(obj.OutList, objItem)
 
-            process_objects(doc.RootObjectsIgnoreLinks, docItem)
+            guiDoc = Gui.getDocument(doc.Name)
+            process_objects(guiDoc.TreeRootObjects, docItem)
             self.form.partList.expandAll()
 
     def onFilterChange(self):

src/Mod/Assembly/UtilsAssembly.py

@@ -308,7 +308,7 @@ def getGlobalPlacement(targetObj, container=None):
 
 
 def isThereOneRootAssembly():
-    for part in App.activeDocument().RootObjectsIgnoreLinks:
+    for part in Gui.activeDocument().TreeRootObjects:
         if part.TypeId == "Assembly::AssemblyObject":
             return True
     return False