Assembly: Insert flexible assembly grounds the correct part (#27206)

* Assembly: Insert flexible assembly grounds the correct part

* [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci

* Assembly: Migrate ObjectToGround to PropertyLinkGlobal to support assembly links

* Update JointObject.py

* Assembly: ViewProviderAssembly fix assembly link deletion issue

* Assembly: ViewProviderAssembly: make sure no duplicates in canDelete

* Assembly CommandInsertLink fix typo

* [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci

---------

Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>

src/Mod/Assembly/CommandInsertLink.py

@@ -495,7 +495,43 @@ class TaskAssemblyInsertLink(QtCore.QObject):
             if len(self.insertionStack) != 1:
                 return
 
-            self.groundedObj = self.insertionStack[0]["addedObject"]
+            targetObj = self.insertionStack[0]["addedObject"]
+
+            # If the object is a flexible AssemblyLink, we should ground its internal 'base' part
+            if targetObj.isDerivedFrom("Assembly::AssemblyLink") and not targetObj.Rigid:
+                linkedAsm = targetObj.LinkedObject
+                if linkedAsm and hasattr(linkedAsm, "Group"):
+                    srcGrounded = None
+                    # Attempt to find the grounded joint in the source assembly
+                    # We look for a joint where JointType is 'Grounded'
+                    for obj in linkedAsm.InListRecursive:
+                        if hasattr(obj, "ObjectToGround"):
+                            srcGrounded = obj.ObjectToGround
+                            break
+
+                    # Search the sub-assembly group for the link pointing to the source grounded object
+                    # Fallback to the first valid part if no grounded joint was found in source
+                    candidate = None
+                    for child in targetObj.Group:
+                        if not candidate and (
+                            child.isDerivedFrom("App::Link") or child.isDerivedFrom("Part::Feature")
+                        ):
+                            candidate = child
+
+                        if (
+                            srcGrounded
+                            and hasattr(child, "LinkedObject")
+                            and child.LinkedObject == srcGrounded
+                        ):
+                            candidate = child
+                            break
+
+                    if not candidate:  # Nothing to ground
+                        return
+
+                    targetObj = candidate
+
+            self.groundedObj = targetObj
             self.groundedJoint = CommandCreateJoint.createGroundedJoint(self.groundedObj)
 
     def increment_counter(self, item):

src/Mod/Assembly/Gui/ViewProviderAssembly.cpp

@@ -1345,20 +1345,24 @@ bool ViewProviderAssembly::canDelete(App::DocumentObject* objBeingDeleted) const
                     continue;
                 }
 
-                if (dynamic_cast<App::PropertyLink*>(parent->getPropertyByName("ObjectToGround"))) {
-                    objToDel.push_back(parent);
+                if (parent->getPropertyByName("ObjectToGround")) {
+                    if (std::ranges::find(objToDel, parent) == objToDel.end()) {
+                        objToDel.push_back(parent);
+                    }
                 }
             }
         }
 
         // Deletes them.
         for (auto* joint : objToDel) {
-            Gui::Command::doCommand(
-                Gui::Command::Doc,
-                "App.getDocument(\"%s\").removeObject(\"%s\")",
-                joint->getDocument()->getName(),
-                joint->getNameInDocument()
-            );
+            if (joint && joint->getNameInDocument() != nullptr) {
+                Gui::Command::doCommand(
+                    Gui::Command::Doc,
+                    "App.getDocument(\"%s\").removeObject(\"%s\")",
+                    joint->getDocument()->getName(),
+                    joint->getNameInDocument()
+                );
+            }
         }
     }
     return res;

src/Mod/Assembly/JointObject.py

@@ -1211,16 +1211,32 @@ class GroundedJoint:
         joint.Proxy = self
         self.joint = joint
 
+        self.createObjectToGroundProperty(joint, obj_to_ground)
+
+    def createObjectToGroundProperty(self, joint, obj_to_ground):
         joint.addProperty(
-            "App::PropertyLink",
+            "App::PropertyLinkGlobal",
             "ObjectToGround",
             "Ground",
             QT_TRANSLATE_NOOP("App::Property", "The object to ground"),
             locked=True,
         )
-
         joint.ObjectToGround = obj_to_ground
 
+    def onDocumentRestored(self, joint):
+        self.migrationScript(joint)
+
+    def migrationScript(self, joint):
+        if (
+            hasattr(joint, "ObjectToGround")
+            and joint.getTypeIdOfProperty("ObjectToGround") == "App::PropertyLink"
+        ):
+            obj_to_ground = joint.ObjectToGround
+            joint.setPropertyStatus("ObjectToGround", "-LockDynamic")
+            joint.removeProperty("ObjectToGround")
+
+            self.createObjectToGroundProperty(joint, obj_to_ground)
+
     def dumps(self):
         return None