Fix #2837. Shared subelements mistakenly caused the subelement append loop to break early. The solution is to traverse one level at a time.

src/ifcopenshell-python/ifcopenshell/api/project/append_asset.py

@@ -183,20 +183,21 @@ class Usecase:
         existing_element = self.get_existing_element(element)
         if existing_element:
             return existing_element
-        # if element.id() in self.added_elements:
-        #    return self.added_elements[element.id()]
         new = self.file.add(element)
         self.added_elements[element.id()] = new
         self.check_inverses(element)
-        for subelement in self.settings["library"].traverse(element)[1:]:
+        subelement_queue = self.settings["library"].traverse(element, max_levels=1)[1:]
+        while subelement_queue:
+            subelement = subelement_queue.pop(0)
             existing_element = self.get_existing_element(subelement)
             if existing_element:
                 self.added_elements[subelement.id()] = existing_element
                 if not self.has_whitelisted_inverses(existing_element):
                     self.check_inverses(subelement)
-                break
+            else:
-            self.added_elements[subelement.id()] = self.file.add(subelement)
+                self.added_elements[subelement.id()] = self.file.add(subelement)
-            self.check_inverses(subelement)
+                self.check_inverses(subelement)
+                subelement_queue.extend(self.settings["library"].traverse(subelement, max_levels=1)[1:])
         return new
 
     def has_whitelisted_inverses(self, element):

src/ifcopenshell-python/test/api/project/test_append_asset.py

@@ -116,6 +116,16 @@ class TestAppendAsset(test.bootstrap.IFC4):
     def test_append_a_type_product_with_its_styles(self):
         library = ifcopenshell.api.run("project.create_file")
         element = ifcopenshell.api.run("root.create_entity", library, ifc_class="IfcWallType")
+        history = library.createIfcOwnerHistory()
+        element.OwnerHistory = history
+
+        material = ifcopenshell.api.run("material.add_material", library, name="Material")
+        rel = ifcopenshell.api.run("material.assign_material", library, product=element, material=material)
+        # We share a history. This ensures that we continue to check all
+        # whitelisted inverses even though one of the subelements (i.e. this
+        # shared history) is already processed. See bug #2837.
+        rel.OwnerHistory = history
+
         item = library.createIfcBoundingBox()
         library.createIfcStyledItem(Item=item)
         mapped_rep = library.createIfcShapeRepresentation(Items=[item])