You can now remove material sets independent of elements

src/ifcopenshell-python/ifcopenshell/api/material/remove_material_set.py

@@ -0,0 +1,48 @@
+# 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 ifcopenshell
+
+
+class Usecase:
+    def __init__(self, file, **settings):
+        self.file = file
+        self.settings = {"material": None}
+        for key, value in settings.items():
+            self.settings[key] = value
+
+    def execute(self):
+        inverse_elements = self.file.get_inverse(self.settings["material"])
+        if self.settings["material"].is_a("IfcMaterialLayerSet"):
+            set_items = self.settings["material"].MaterialLayers or []
+        elif self.settings["material"].is_a("IfcMaterialProfileSet"):
+            set_items = self.settings["material"].MaterialProfiles or []
+        elif self.settings["material"].is_a("IfcMaterialConstituentSet"):
+            set_items = self.settings["material"].MaterialConstituents or []
+        elif self.settings["material"].is_a("IfcMaterialList"):
+            set_items = []
+        for set_item in set_items:
+            self.file.remove(set_item)
+        self.file.remove(self.settings["material"])
+        for inverse in inverse_elements:
+            if inverse.is_a("IfcRelAssociatesMaterial"):
+                self.file.remove(inverse)
+            elif inverse.is_a("IfcMaterialProperties"):
+                for prop in inverse.Properties or []:
+                    self.file.remove(prop)
+                self.file.remove(inverse)

src/ifcopenshell-python/test/api/material/test_remove_material_set.py

@@ -0,0 +1,53 @@
+# 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
+
+
+class TestRemoveMaterialSet(test.bootstrap.IFC4):
+    def test_removing_material_set(self):
+        material = ifcopenshell.api.run("material.add_material_set", self.file, set_type="IfcMaterialLayerSet")
+        ifcopenshell.api.run("material.remove_material_set", self.file, material=material)
+        assert len(self.file.by_type("IfcMaterialLayerSet")) == 0
+
+    def test_removing_material_set_with_associations(self):
+        wall = ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcWall")
+        material = ifcopenshell.api.run("material.add_material_set", self.file, set_type="IfcMaterialLayerSet")
+        ifcopenshell.api.run("material.assign_material", self.file, product=wall, material=material)
+        ifcopenshell.api.run("material.remove_material_set", self.file, material=material)
+        assert len(self.file.by_type("IfcMaterialLayerSet")) == 0
+        assert len(self.file.by_type("IfcRelAssociatesMaterial")) == 0
+
+    def test_removing_a_material_set_with_set_items_but_preserving_materials(self):
+        material = ifcopenshell.api.run("material.add_material", self.file)
+        material_set = ifcopenshell.api.run("material.add_material_set", self.file, set_type="IfcMaterialLayerSet")
+        ifcopenshell.api.run("material.add_layer", self.file, layer_set=material_set, material=material)
+        ifcopenshell.api.run("material.remove_material_set", self.file, material=material_set)
+        assert len(self.file.by_type("IfcMaterialLayerSet")) == 0
+        assert len(self.file.by_type("IfcMaterialLayer")) == 0
+        assert len(self.file.by_type("IfcMaterial")) == 1
+
+    def test_removing_a_material_set_with_properties(self):
+        material = ifcopenshell.api.run("material.add_material_set", self.file, set_type="IfcMaterialLayerSet")
+        pset = ifcopenshell.api.run("pset.add_pset", self.file, product=material, name="Foo_Bar")
+        ifcopenshell.api.run("pset.edit_pset", self.file, pset=pset, properties={"Foo": "Bar"})
+        assert material.HasProperties
+        ifcopenshell.api.run("material.remove_material_set", self.file, material=material)
+        assert len(self.file.by_type("IfcMaterialProperties")) == 0
+        assert len(self.file.by_type("IfcPropertySingleValue")) == 0