Changing aggregation now ensures spatial containment is mutually exclusive to prevent invalid IFC data

src/blenderbim/pytest.ini

@@ -1,5 +1,6 @@
 [pytest]
 markers =
+    aggregate
     context
     geometry
     owner

src/ifcopenshell-python/ifcopenshell/api/aggregate/assign_object.py

@@ -26,6 +26,10 @@ class Usecase:
         if decomposes and decomposes == is_decomposed_by:
             return
 
+        container = ifcopenshell.util.element.get_container(self.settings["product"], should_get_direct=True)
+        if container:
+            ifcopenshell.api.run("spatial.remove_container", self.file, product=self.settings["product"])
+
         if decomposes:
             related_objects = list(decomposes.RelatedObjects)
             related_objects.remove(self.settings["product"])
@@ -50,4 +54,15 @@ class Usecase:
                     "RelatingObject": self.settings["relating_object"],
                 }
             )
+
+        placement = getattr(self.settings["product"], "ObjectPlacement", None)
+        if placement and placement.is_a("IfcLocalPlacement"):
+            ifcopenshell.api.run(
+                "geometry.edit_object_placement",
+                self.file,
+                product=self.settings["product"],
+                matrix=ifcopenshell.util.placement.get_local_placement(self.settings["product"].ObjectPlacement),
+                is_si=False,
+            )
+
         return is_decomposed_by

src/ifcopenshell-python/ifcopenshell/api/spatial/assign_container.py

@@ -60,3 +60,5 @@ class Usecase:
                 matrix=ifcopenshell.util.placement.get_local_placement(self.settings["product"].ObjectPlacement),
                 is_si=False,
             )
+
+        return contains_elements

src/ifcopenshell-python/ifcopenshell/util/element.py

@@ -78,12 +78,16 @@ def get_material(element, should_skip_usage=False):
         return get_material(relating_type, should_skip_usage)
 
 
-def get_container(element):
+def get_container(element, should_get_direct=False):
-    aggregate = get_aggregate(element)
+    if should_get_direct:
-    if aggregate:
+        if hasattr(element, "ContainedInStructure") and element.ContainedInStructure:
-        return get_container(aggregate)
+            return element.ContainedInStructure[0].RelatingStructure
-    if hasattr(element, "ContainedInStructure") and element.ContainedInStructure:
+    else:
-        return element.ContainedInStructure[0].RelatingStructure
+        aggregate = get_aggregate(element)
+        if aggregate:
+            return get_container(aggregate, should_get_direct)
+        if hasattr(element, "ContainedInStructure") and element.ContainedInStructure:
+            return element.ContainedInStructure[0].RelatingStructure
 
 
 def get_decomposition(element):

src/ifcopenshell-python/test/api/aggregate/test_assign_object.py

@@ -0,0 +1,101 @@
+import numpy
+import pytest
+import test.bootstrap
+import ifcopenshell.api
+import ifcopenshell.util.element
+import ifcopenshell.util.placement
+
+
+class TestAssignObject(test.bootstrap.IFC4):
+    def test_assigning_a_container(self):
+        element = ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcSite")
+        subelement = ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcBuilding")
+        rel = ifcopenshell.api.run("aggregate.assign_object", self.file, product=subelement, relating_object=element)
+        assert ifcopenshell.util.element.get_aggregate(subelement) == element
+        assert rel.is_a("IfcRelAggregates")
+
+    def test_doing_nothing_if_the_aggregate_is_already_assigned(self):
+        element = ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcSite")
+        subelement = ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcBuilding")
+        ifcopenshell.api.run("aggregate.assign_object", self.file, product=subelement, relating_object=element)
+        total_elements = len([e for e in self.file])
+        ifcopenshell.api.run("aggregate.assign_object", self.file, product=subelement, relating_object=element)
+        assert len([e for e in self.file]) == total_elements
+
+    def test_that_old_aggregate_relationships_are_updated_if_they_still_have_elements(self):
+        element1 = ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcSite")
+        element2 = ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcSite")
+        subelement1 = ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcBuilding")
+        subelement2 = ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcBuilding")
+        ifcopenshell.api.run("aggregate.assign_object", self.file, product=subelement1, relating_object=element1)
+        ifcopenshell.api.run("aggregate.assign_object", self.file, product=subelement2, relating_object=element1)
+        rel = subelement1.Decomposes[0]
+        assert len(rel.RelatedObjects) == 2
+        ifcopenshell.api.run("aggregate.assign_object", self.file, product=subelement1, relating_object=element2)
+        assert len(rel.RelatedObjects) == 1
+
+    def test_that_old_aggregate_relationships_are_purged_if_no_more_elements_are_contained(self):
+        element1 = ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcSite")
+        element2 = ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcSite")
+        subelement1 = ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcBuilding")
+        ifcopenshell.api.run("aggregate.assign_object", self.file, product=subelement1, relating_object=element1)
+        rel_id = subelement1.Decomposes[0].id()
+        ifcopenshell.api.run("aggregate.assign_object", self.file, product=subelement1, relating_object=element2)
+        with pytest.raises(RuntimeError):
+            self.file.by_id(rel_id)
+
+    def test_assigning_a_container_does_not_shift_object_placements(self):
+        ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcProject")
+        ifcopenshell.api.run("unit.assign_unit", self.file)
+        element1 = ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcSite")
+        element2 = ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcSite")
+        subelement = ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcBuilding")
+        ifcopenshell.api.run("aggregate.assign_object", self.file, product=subelement, relating_object=element1)
+        matrix1 = numpy.array(
+            (
+                (1.0, 0.0, 0.0, 1.0),
+                (0.0, 1.0, 0.0, 1.0),
+                (0.0, 0.0, 1.0, 1.0),
+                (0.0, 0.0, 0.0, 1.0),
+            )
+        )
+        matrix2 = numpy.array(
+            (
+                (1.0, 0.0, 0.0, 2.0),
+                (0.0, 1.0, 0.0, 2.0),
+                (0.0, 0.0, 1.0, 2.0),
+                (0.0, 0.0, 0.0, 1.0),
+            )
+        )
+        ifcopenshell.api.run(
+            "geometry.edit_object_placement", self.file, product=element1, matrix=matrix1.copy(), is_si=False
+        )
+        ifcopenshell.api.run(
+            "geometry.edit_object_placement", self.file, product=element2, matrix=matrix2.copy(), is_si=False
+        )
+        ifcopenshell.api.run(
+            "geometry.edit_object_placement", self.file, product=subelement, matrix=matrix1.copy(), is_si=False
+        )
+        ifcopenshell.api.run("aggregate.assign_object", self.file, product=subelement, relating_object=element2)
+        assert subelement.ObjectPlacement.PlacementRelTo.PlacesObject[0] == element2
+        assert numpy.array_equal(ifcopenshell.util.placement.get_local_placement(subelement.ObjectPlacement), matrix1)
+
+    def test_not_updating_placement_if_placement_is_not_relative(self):
+        ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcProject")
+        ifcopenshell.api.run("unit.assign_unit", self.file)
+        element = ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcSite")
+        subelement = ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcBuilding")
+        placement = self.file.createIfcGridPlacement()
+        subelement.ObjectPlacement = placement
+        ifcopenshell.api.run("aggregate.assign_object", self.file, product=subelement, relating_object=element)
+        assert subelement.ObjectPlacement == placement
+
+    def test_removing_containment_if_it_exists(self):
+        ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcProject")
+        ifcopenshell.api.run("unit.assign_unit", self.file)
+        element = ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcElementAssembly")
+        container = ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcBuildingStorey")
+        subelement = ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcWall")
+        ifcopenshell.api.run("spatial.assign_container", self.file, product=subelement, relating_structure=container)
+        ifcopenshell.api.run("aggregate.assign_object", self.file, product=subelement, relating_object=element)
+        assert not ifcopenshell.util.element.get_container(subelement, should_get_direct=True)

src/ifcopenshell-python/test/api/spatial/test_assign_container.py

@@ -10,8 +10,11 @@ class TestAssignContainer(test.bootstrap.IFC4):
     def test_assigning_a_container(self):
         element = ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcBuilding")
         subelement = ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcWall")
-        ifcopenshell.api.run("spatial.assign_container", self.file, product=subelement, relating_structure=element)
+        rel = ifcopenshell.api.run(
+            "spatial.assign_container", self.file, product=subelement, relating_structure=element
+        )
         assert ifcopenshell.util.element.get_container(subelement) == element
+        assert rel.is_a("IfcRelContainedInSpatialStructure")
 
     def test_doing_nothing_if_the_container_is_already_assigned(self):
         element = ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcBuilding")

src/ifcopenshell-python/test/util/test_element.py

@@ -178,6 +178,14 @@ class TestGetContainerIFC4(test.bootstrap.IFC4):
         ifcopenshell.api.run("aggregate.assign_object", self.file, product=subelement, relating_object=element)
         assert ifcopenshell.util.element.get_container(subelement) == building
 
+    def test_getting_nothing_if_we_enforce_only_getting_direct_spatial_containers(self):
+        subelement = ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcWall")
+        element = ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcElementAssembly")
+        building = ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcBuilding")
+        ifcopenshell.api.run("spatial.assign_container", self.file, product=element, relating_structure=building)
+        ifcopenshell.api.run("aggregate.assign_object", self.file, product=subelement, relating_object=element)
+        assert ifcopenshell.util.element.get_container(subelement, should_get_direct=True) is None
+
 
 class TestGetDecompositionIFC4(test.bootstrap.IFC4):
     def test_getting_decomposed_subelements_of_an_element(self):