root.remove_product - fix some cases producing invalid ifc #4313

always remove IfcRelNests
1) if product is RelatingObject
2) if product is the only RelatedObject

src/ifcopenshell-python/ifcopenshell/api/root/remove_product.py

@@ -104,6 +104,13 @@ class Usecase:
             ):
                 ifcopenshell.api.run("grid.remove_grid_axis", self.file, axis=axis)
 
+        def element_exists(element_id):
+            try:
+                self.file.by_id(element_id)
+                return True
+            except RuntimeError:
+                return False
+
         # TODO: remove object placement and other relationships
         for inverse_id in [i.id() for i in self.file.get_inverse(self.settings["product"])]:
             try:
@@ -144,14 +151,21 @@ class Usecase:
                     ifcopenshell.util.element.remove_deep2(self.file, history)
             elif inverse.is_a("IfcRelNests"):
                 if inverse.RelatingObject == self.settings["product"]:
+                    inverse_id = inverse.id()
                     for subelement in inverse.RelatedObjects:
                         if subelement.is_a("IfcDistributionPort"):
                             ifcopenshell.api.run("root.remove_product", self.file, product=subelement)
-                    if not inverse.RelatedObjects:
+                    # IfcRelNests could have been already deleted after removing one of the products
+                    if element_exists(inverse_id):
                         history = inverse.OwnerHistory
                         self.file.remove(inverse)
                         if history:
                             ifcopenshell.util.element.remove_deep2(self.file, history)
+                elif inverse.RelatedObjects == (self.settings["product"],):
+                    history = inverse.OwnerHistory
+                    self.file.remove(inverse)
+                    if history:
+                        ifcopenshell.util.element.remove_deep2(self.file, history)
             elif inverse.is_a("IfcRelAggregates"):
                 if inverse.RelatingObject == self.settings["product"] or len(inverse.RelatedObjects) == 1:
                     history = inverse.OwnerHistory

src/ifcopenshell-python/test/api/root/test_remove_product.py

@@ -187,6 +187,28 @@ class TestRemoveProduct(test.bootstrap.IFC4):
         assert len(self.file.by_type("IfcRelNests")) == 0
         assert len(self.file.by_type("IfcDistributionPort")) == 0
 
+    def test_removing_all_nesting_relationships_of_a_whole(self):
+        element = ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcWall")
+        subelement = ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcBeam")
+        ifcopenshell.api.run("nest.assign_object", self.file, related_object=subelement, relating_object=element)
+        total_entities = len(list(self.file))
+        ifcopenshell.api.run("root.remove_product", self.file, product=element)
+        assert len(list(self.file)) == total_entities - 2
+        assert len(self.file.by_type("IfcRelNests")) == 0
+        assert len(self.file.by_type("IfcWall")) == 0
+        assert len(self.file.by_type("IfcBeam")) == 1
+
+    def test_removing_all_nesting_relationships_of_a_part(self):
+        element = ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcWall")
+        subelement = ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcBeam")
+        ifcopenshell.api.run("nest.assign_object", self.file, related_object=subelement, relating_object=element)
+        total_entities = len(list(self.file))
+        ifcopenshell.api.run("root.remove_product", self.file, product=subelement)
+        assert len(list(self.file)) == total_entities - 2
+        assert len(self.file.by_type("IfcRelNests")) == 0
+        assert len(self.file.by_type("IfcWall")) == 1
+        assert len(self.file.by_type("IfcBeam")) == 0
+
     def test_removing_all_aggregate_relationships_of_a_whole(self):
         element = ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcElementAssembly")
         subelement = ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcBeam")