Object metadata to double check element belongs to the current project

Just to be safe if it got from other Blender session and there is an IFC element with the same id in the current project. I guess we can't check it anywhere but information in "Object metadata" should very accurate as here user might decide to unlink it.

src/blenderbim/blenderbim/bim/module/root/data.py

@@ -23,6 +23,7 @@ import ifcopenshell.util.schema
 from ifcopenshell.util.doc import get_entity_doc, get_predefined_type_doc, get_class_suggestions
 import blenderbim.tool as tool
 from blenderbim.bim.ifc import IfcStore
+from typing import Union
 
 
 def refresh():
@@ -30,6 +31,7 @@ def refresh():
 
 
 class IfcClassData:
+    element: Union[ifcopenshell.entity_instance, None] = None
     data = {}
     is_loaded = False
 
@@ -41,6 +43,7 @@ class IfcClassData:
         cls.data["ifc_classes"] = cls.ifc_classes()
         cls.data["ifc_classes_suggestions"] = cls.ifc_classes_suggestions()  # Call AFTER cls.ifc_classes()
         cls.data["contexts"] = cls.contexts()
+
         cls.data["has_entity"] = cls.has_entity()
         cls.data["name"] = cls.name()
         cls.data["has_inherited_predefined_type"] = cls.has_inherited_predefined_type()
@@ -147,15 +150,27 @@ class IfcClassData:
         return results
 
     @classmethod
-    def has_entity(cls):
+    def has_entity(cls) -> Union[ifcopenshell.entity_instance, None]:
-        try:
+        obj = bpy.context.active_object
-            return tool.Ifc.get_entity(bpy.context.active_object)
+        cls.element = None
-        except:
+        if not obj:
-            pass
+            return
+
+        element = tool.Ifc.get_entity(obj)
+        if not element:
+            return
+
+        # Double check
+        linked_obj = tool.Ifc.get_object(element)
+        if linked_obj != obj:
+            return
+
+        cls.element = element
+        return cls.element
 
     @classmethod
-    def name(cls):
+    def name(cls) -> Union[str, None]:
-        element = tool.Ifc.get_entity(bpy.context.view_layer.objects.active)
+        element = cls.element
         if not element:
             return
         name = element.is_a()
@@ -165,24 +180,24 @@ class IfcClassData:
         return name
 
     @classmethod
-    def has_inherited_predefined_type(cls):
+    def has_inherited_predefined_type(cls) -> bool:
-        element = tool.Ifc.get_entity(bpy.context.view_layer.objects.active)
+        element = cls.element
         if not element:
-            return
+            return False
         if element_type := ifcopenshell.util.element.get_type(element):
             # Allow for None due to https://github.com/buildingSMART/IFC4.3.x-development/issues/818
             return ifcopenshell.util.element.get_predefined_type(element_type) not in ("NOTDEFINED", None)
         return False
 
     @classmethod
-    def ifc_class(cls):
+    def ifc_class(cls) -> Union[str, None]:
-        element = tool.Ifc.get_entity(bpy.context.view_layer.objects.active)
+        element = cls.element
         if element:
             return element.is_a()
 
     @classmethod
-    def can_reassign_class(cls):
+    def can_reassign_class(cls) -> bool:
-        element = tool.Ifc.get_entity(bpy.context.view_layer.objects.active)
+        element = cls.element
         if element:
             if element.is_a("IfcOpeningElement") or element.is_a("IfcOpeningStandardCase"):
                 return False
@@ -191,3 +206,4 @@ class IfcClassData:
             for product in cls.ifc_products():
                 if element.is_a(product[0]):
                     return True
+        return False