fix group.update_group_products to work with multiple rels

src/ifcopenshell-python/ifcopenshell/api/group/update_group_products.py

@@ -19,6 +19,7 @@
 import ifcopenshell
 import ifcopenshell.api
 import ifcopenshell.guid
+import ifcopenshell.util.element
 
 
 def update_group_products(
@@ -60,11 +61,17 @@ def update_group_products(
             }
         )
     else:
-        # assumes 1:1 cardinality, will need to be updated to reflect IFC4 changes
-        # where the cardinality is 0:? - vulevukusej
-        rel = settings["group"].IsGroupedBy[0]
-        existing_sub_groups = [g for g in rel.RelatedObjects if g.is_a("IfcGroup")]
+        rels = settings["group"].IsGroupedBy
+        objects = set(settings["products"])
+        for rel in rels:
+            objects.update([g for g in rel.RelatedObjects if g.is_a("IfcGroup")])
+        to_purge = rels[1:]
 
-        rel.RelatedObjects = settings["products"]
-        for g in existing_sub_groups:
-            rel.RelatedObjects.add(g)
+        for rel in to_purge:
+            history = rel.OwnerHistory
+            file.remove(rel)
+            if history:
+                ifcopenshell.util.element.remove_deep2(file, history)
+
+        rels[0].RelatedObjects = list(objects)
+        return rels[0]

src/ifcopenshell-python/test/api/group/test_update_group_products.py

@@ -0,0 +1,54 @@
+# IfcOpenShell - IFC toolkit and geometry engine
+# Copyright (C) 2022 Dion Moult <dion@thinkmoult.com>
+#
+# This file is part of IfcOpenShell.
+#
+# IfcOpenShell is free software: you can redistribute it and/or modify
+# it under the terms of the GNU Lesser General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# IfcOpenShell is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU Lesser General Public License for more details.
+#
+# You should have received a copy of the GNU Lesser General Public License
+# along with IfcOpenShell.  If not, see <http://www.gnu.org/licenses/>.
+
+import test.bootstrap
+import ifcopenshell.api
+import ifcopenshell.util.element
+
+
+class TestUpdateGroupProductsIFC2X3(test.bootstrap.IFC2X3):
+    def test_update_group_without_products(self):
+        elements = [ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcWall") for i in range(4)]
+        group = ifcopenshell.api.run("group.add_group", self.file)
+        ifcopenshell.api.run("group.update_group_products", self.file, products=elements, group=group)
+        assert set(ifcopenshell.util.element.get_grouped_by(group)) == set(elements)
+
+    def test_update_group_products(self):
+        elements = [ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcWall") for i in range(4)]
+        group = ifcopenshell.api.run("group.add_group", self.file)
+        ifcopenshell.api.run("group.assign_group", self.file, products=elements[:2], group=group)
+        ifcopenshell.api.run("group.update_group_products", self.file, products=elements[2:], group=group)
+        assert set(ifcopenshell.util.element.get_grouped_by(group)) == set(elements[2:])
+        assert ifcopenshell.util.element.get_groups(elements[0]) == []
+        assert ifcopenshell.util.element.get_groups(elements[1]) == []
+
+
+class TestUpdateGroupProductsIFC4(test.bootstrap.IFC4, TestUpdateGroupProductsIFC2X3):
+    def test_update_group_products(self):
+        # in ifc4 IfcGroup can have multiple rels
+        elements = [ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcWall") for i in range(4)]
+        group = ifcopenshell.api.run("group.add_group", self.file)
+
+        self.file.create_entity("IfcRelAssignsToGroup", RelatingGroup=group, RelatedObjects=elements[:1])
+        self.file.create_entity("IfcRelAssignsToGroup", RelatingGroup=group, RelatedObjects=elements[1:2])
+
+        ifcopenshell.api.run("group.update_group_products", self.file, products=elements[2:], group=group)
+        assert len(self.file.by_type("IfcRelAssignsToGroup")) == 1
+        assert set(ifcopenshell.util.element.get_grouped_by(group)) == set(elements[2:])
+        assert ifcopenshell.util.element.get_groups(elements[0]) == []
+        assert ifcopenshell.util.element.get_groups(elements[1]) == []