material.assign_material - support batching #4474

src/blenderbim/blenderbim/bim/module/model/mep.py

@@ -542,7 +542,7 @@ class MEPGenerator:
             ifc_representation_class=None,
         )
 
-        rel = ifcopenshell.api.run("material.assign_material", ifc_file, product=element, type="IfcMaterialProfileSet")
+        rel = ifcopenshell.api.run("material.assign_material", ifc_file, products=[element], type="IfcMaterialProfileSet")
         profile_set = rel.RelatingMaterial
         material_profile = ifcopenshell.api.run(
             "material.add_profile", ifc_file, profile_set=profile_set, material=material

src/blenderbim/blenderbim/bim/module/model/product.py

@@ -515,7 +515,7 @@ def ensure_material_assigned(usecase_path, ifc_file, settings):
     if usecase_path == "material.assign_material":
         if not settings.get("material", None):
             return
-        elements = [settings["product"]]
+        elements = settings["products"]
     else:
         elements = []
         for rel in ifc_file.by_type("IfcRelAssociatesMaterial"):

src/blenderbim/blenderbim/bim/module/type/operator.py

@@ -283,7 +283,7 @@ class AddType(bpy.types.Operator, tool.Ifc.Operator):
             else:
                 material = self.add_default_material()
             rel = ifcopenshell.api.run(
-                "material.assign_material", ifc_file, product=element, type="IfcMaterialLayerSet"
+                "material.assign_material", ifc_file, products=[element], type="IfcMaterialLayerSet"
             )
             layer_set = rel.RelatingMaterial
             layer = ifcopenshell.api.run("material.add_layer", ifc_file, layer_set=layer_set, material=material)
@@ -361,7 +361,7 @@ class AddType(bpy.types.Operator, tool.Ifc.Operator):
                     )
 
             rel = ifcopenshell.api.run(
-                "material.assign_material", ifc_file, product=element, type="IfcMaterialProfileSet"
+                "material.assign_material", ifc_file, products=[element], type="IfcMaterialProfileSet"
             )
             profile_set = rel.RelatingMaterial
             material_profile = ifcopenshell.api.run(

src/blenderbim/blenderbim/core/material.py

@@ -102,7 +102,7 @@ def assign_material(ifc, material_tool, material_type, objects):
         element = ifc.get_entity(obj)
         if not element:
             continue
-        ifc.run("material.assign_material", product=element, type=material_type, material=material)
+        ifc.run("material.assign_material", products=[element], type=material_type, material=material)
         assigned_material = material_tool.get_material(element)
         if material_tool.is_a_material_set(assigned_material):
             material_tool.add_material_to_set(material_set=assigned_material, material=material)

src/blenderbim/blenderbim/tool/material.py

@@ -219,7 +219,7 @@ class Material(blenderbim.core.tool.Material):
             material = tool.Ifc.get().by_type("IfcMaterial")[0]
         else:
             blenderbim.core.material.unassign_material(tool.Ifc, tool.Material, objects=[tool.Ifc.get_object(element)])
-        tool.Ifc.run("material.assign_material", product=element, type="IfcMaterialProfileSet", material=material)
+        tool.Ifc.run("material.assign_material", products=[element], type="IfcMaterialProfileSet", material=material)
         assinged_material = cls.get_material(element)
         material_profile = tool.Ifc.run("material.add_profile", profile_set=assinged_material, material=material)
         return material_profile

src/blenderbim/scripts/generate_au_library.py

@@ -188,7 +188,7 @@ class LibraryGenerator:
     def create_layer_set_type(self, name, data):
         element = ifcopenshell.api.run("root.create_entity", self.file, ifc_class=data["type"], name=name)
         element.Description = data["Description"]
-        rel = ifcopenshell.api.run("material.assign_material", self.file, product=element, type="IfcMaterialLayerSet")
+        rel = ifcopenshell.api.run("material.assign_material", self.file, products=[element], type="IfcMaterialLayerSet")
         layer_set = rel.RelatingMaterial
         for layer_data in data["Layers"]:
             layer = ifcopenshell.api.run(
@@ -201,7 +201,7 @@ class LibraryGenerator:
 
     def create_layer_type(self, ifc_class, name, thickness):
         element = ifcopenshell.api.run("root.create_entity", self.file, ifc_class=ifc_class, name=name)
-        rel = ifcopenshell.api.run("material.assign_material", self.file, product=element, type="IfcMaterialLayerSet")
+        rel = ifcopenshell.api.run("material.assign_material", self.file, products=[element], type="IfcMaterialLayerSet")
         layer_set = rel.RelatingMaterial
         layer = ifcopenshell.api.run("material.add_layer", self.file, layer_set=layer_set, material=self.materials["TBD"]["ifc"])
         layer.LayerThickness = thickness
@@ -210,7 +210,7 @@ class LibraryGenerator:
 
     def create_profile_type(self, ifc_class, name, profile):
         element = ifcopenshell.api.run("root.create_entity", self.file, ifc_class=ifc_class, name=name)
-        rel = ifcopenshell.api.run("material.assign_material", self.file, product=element, type="IfcMaterialProfileSet")
+        rel = ifcopenshell.api.run("material.assign_material", self.file, products=[element], type="IfcMaterialProfileSet")
         profile_set = rel.RelatingMaterial
         material_profile = ifcopenshell.api.run(
             "material.add_profile", self.file, profile_set=profile_set, material=self.materials["TBD"]["ifc"]

src/blenderbim/scripts/generate_demo_library.py

@@ -205,7 +205,7 @@ class LibraryGenerator:
 
     def create_layer_type(self, ifc_class, name, thickness):
         element = ifcopenshell.api.run("root.create_entity", self.file, ifc_class=ifc_class, name=name)
-        rel = ifcopenshell.api.run("material.assign_material", self.file, product=element, type="IfcMaterialLayerSet")
+        rel = ifcopenshell.api.run("material.assign_material", self.file, products=[element], type="IfcMaterialLayerSet")
         layer_set = rel.RelatingMaterial
         layer = ifcopenshell.api.run("material.add_layer", self.file, layer_set=layer_set, material=self.material)
         layer.LayerThickness = thickness
@@ -214,7 +214,7 @@ class LibraryGenerator:
 
     def create_profile_type(self, ifc_class, name, profile):
         element = ifcopenshell.api.run("root.create_entity", self.file, ifc_class=ifc_class, name=name)
-        rel = ifcopenshell.api.run("material.assign_material", self.file, product=element, type="IfcMaterialProfileSet")
+        rel = ifcopenshell.api.run("material.assign_material", self.file, products=[element], type="IfcMaterialProfileSet")
         profile_set = rel.RelatingMaterial
         material_profile = ifcopenshell.api.run(
             "material.add_profile", self.file, profile_set=profile_set, material=self.material

src/blenderbim/scripts/generate_furniture_library.py

@@ -1803,7 +1803,7 @@ class LibraryGenerator:
     def create_layer_set_type(self, name, data):
         element = ifcopenshell.api.run("root.create_entity", self.file, ifc_class=data["type"], name=name)
         element.Description = data["Description"]
-        rel = ifcopenshell.api.run("material.assign_material", self.file, product=element, type="IfcMaterialLayerSet")
+        rel = ifcopenshell.api.run("material.assign_material", self.file, products=[element], type="IfcMaterialLayerSet")
         layer_set = rel.RelatingMaterial
         for layer_data in data["Layers"]:
             layer = ifcopenshell.api.run(
@@ -1816,7 +1816,7 @@ class LibraryGenerator:
 
     def create_layer_type(self, ifc_class, name, thickness):
         element = ifcopenshell.api.run("root.create_entity", self.file, ifc_class=ifc_class, name=name)
-        rel = ifcopenshell.api.run("material.assign_material", self.file, product=element, type="IfcMaterialLayerSet")
+        rel = ifcopenshell.api.run("material.assign_material", self.file, products=[element], type="IfcMaterialLayerSet")
         layer_set = rel.RelatingMaterial
         layer = ifcopenshell.api.run(
             "material.add_layer", self.file, layer_set=layer_set, material=self.materials["TBD"]["ifc"]
@@ -1827,7 +1827,7 @@ class LibraryGenerator:
 
     def create_profile_type(self, ifc_class, name, profile):
         element = ifcopenshell.api.run("root.create_entity", self.file, ifc_class=ifc_class, name=name)
-        rel = ifcopenshell.api.run("material.assign_material", self.file, product=element, type="IfcMaterialProfileSet")
+        rel = ifcopenshell.api.run("material.assign_material", self.file, products=[element], type="IfcMaterialProfileSet")
         profile_set = rel.RelatingMaterial
         material_profile = ifcopenshell.api.run(
             "material.add_profile",

src/blenderbim/scripts/generate_steel_profiles_library.py

@@ -175,7 +175,7 @@ class LibraryGenerator:
 
     def create_profile_type(self, ifc_class, name, profile):
         element = ifcopenshell.api.run("root.create_entity", self.file, ifc_class=ifc_class, name=name)
-        rel = ifcopenshell.api.run("material.assign_material", self.file, product=element, type="IfcMaterialProfileSet")
+        rel = ifcopenshell.api.run("material.assign_material", self.file, products=[element], type="IfcMaterialProfileSet")
         profile_set = rel.RelatingMaterial
         material_profile = ifcopenshell.api.run(
             "material.add_profile", self.file, profile_set=profile_set, material=self.material

src/blenderbim/test/tool/test_material.py

@@ -79,7 +79,7 @@ class TestGetElementsByMaterial(NewFile):
         tool.Ifc.set(ifc)
         element = ifcopenshell.api.run("root.create_entity", ifc, ifc_class="IfcWall")
         material = ifcopenshell.api.run("material.add_material", ifc)
-        ifcopenshell.api.run("material.assign_material", ifc, product=element, material=material)
+        ifcopenshell.api.run("material.assign_material", ifc, products=[element], material=material)
         assert subject.get_elements_by_material(material) == {element}
 
 

src/ifcopenshell-python/docs/ifcopenshell-python/geometry_creation.rst

@@ -686,7 +686,7 @@ responsibility to make sure the geometry is correct.
     ifcopenshell.api.run("material.edit_layer", model, layer=layer, attributes={"LayerThickness": 13})
 
     # Great! Let's assign our material set to our wall type.
-    ifcopenshell.api.run("material.assign_material", model, product=wall_type, material=material_set)
+    ifcopenshell.api.run("material.assign_material", model, products=[wall_type], material=material_set)
 
     # Now, let's create a wall at the origin.
     wall = ifcopenshell.api.run("root.create_entity", model, ifc_class="IfcWall")
@@ -742,7 +742,7 @@ responsibility to make sure the geometry is correct.
     ifcopenshell.api.run("material.add_profile", model, profile_set=material_set, material=steel, profile=hea100)
 
     # Great! Let's assign our material set to our beam type.
-    ifcopenshell.api.run("material.assign_material", model, product=beam_type, material=material_set)
+    ifcopenshell.api.run("material.assign_material", model, products=[beam_type], material=material_set)
 
     # Now, let's create a beam at the origin.
     beam = ifcopenshell.api.run("root.create_entity", model, ifc_class="IfcBeam")

src/ifcopenshell-python/ifcopenshell/api/__init__.py

@@ -85,6 +85,9 @@ ARGUMENTS_DEPRECATION = {
     "system.unassign_system": partial(
         batching_argument_deprecation, prev_argument="product", new_argument="products"
     ),
+    "material.assign_material": partial(
+        batching_argument_deprecation, prev_argument="product", new_argument="products"
+    ),
 }
 
 

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

@@ -78,7 +78,7 @@ class Usecase:
             # our window too, but to keep this example simple, geometry is
             # optional and it is enough to say that this window is made out of
             # aluminium and glass.
-            ifcopenshell.api.run("material.assign_material", model, product=window_type, material=material_set)
+            ifcopenshell.api.run("material.assign_material", model, products=[window_type], material=material_set)
         """
         self.file = file
         self.settings = {"constituent_set": constituent_set, "material": material}

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

@@ -76,7 +76,7 @@ class Usecase:
             ifcopenshell.api.run("material.edit_layer", model, layer=layer, attributes={"LayerThickness": 13})
 
             # Great! Let's assign our material set to our wall type.
-            ifcopenshell.api.run("material.assign_material", model, product=wall_type, material=material_set)
+            ifcopenshell.api.run("material.assign_material", model, products=[wall_type], material=material_set)
         """
         self.file = file
         self.settings = {"layer_set": layer_set, "material": material}

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

@@ -77,7 +77,7 @@ class Usecase:
             # our window too, but to keep this example simple, geometry is
             # optional and it is enough to say that this window is made out of
             # aluminium and glass.
-            ifcopenshell.api.run("material.assign_material", model, product=window_type, material=material_set)
+            ifcopenshell.api.run("material.assign_material", model, products=[window_type], material=material_set)
         """
         self.file = file
         self.settings = {"material_list": material_list, "material": material}

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

@@ -68,7 +68,7 @@ class Usecase:
 
             # Assign the concrete material to that bench. Note that no colour
             # "Style" has been specified.
-            ifcopenshell.api.run("material.assign_material", model, product=concrete_bench, material=concrete)
+            ifcopenshell.api.run("material.assign_material", model, products=[concrete_bench], material=concrete)
         """
         self.file = file
         self.settings = {"name": name or "Unnamed", "category": category}

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

@@ -100,7 +100,7 @@ class Usecase:
             ifcopenshell.api.run("material.edit_layer", model, layer=layer, attributes={"LayerThickness": 13})
 
             # Great! Let's assign our material set to our wall type.
-            ifcopenshell.api.run("material.assign_material", model, product=wall_type, material=material_set)
+            ifcopenshell.api.run("material.assign_material", model, products=[wall_type], material=material_set)
         """
         self.file = file
         self.settings = {"name": name or "Unnamed", "set_type": set_type or "IfcMaterialConstituentSet"}

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

@@ -79,7 +79,7 @@ class Usecase:
                 profile_set=material_set, material=steel, profile=hea100)
 
             # Great! Let's assign our material set to our beam type.
-            ifcopenshell.api.run("material.assign_material", model, product=beam_type, material=material_set)
+            ifcopenshell.api.run("material.assign_material", model, products=[beam_type], material=material_set)
         """
         self.file = file
         self.settings = {"profile_set": profile_set, "material": material, "profile": profile}

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

@@ -27,11 +27,11 @@ class Usecase:
     def __init__(
         self,
         file: ifcopenshell.file,
-        product: ifcopenshell.entity_instance,
+        products: list[ifcopenshell.entity_instance],
         type: str = "IfcMaterial",
         material: Optional[ifcopenshell.entity_instance] = None,
     ):
-        """Assigns a material to a product
+        """Assigns a material to the list of products
 
         Will unassign previously assigned material.
 
@@ -62,9 +62,9 @@ class Usecase:
         This allows individual occurrences to override the layered or profiled
         construction offset from a reference line.
 
-        :param product: The IfcProduct to assign the material or material set
+        :param products: The list of IfcProducts to assign the material or material set
             to.
-        :type product: ifcopenshell.entity_instance.entity_instance
+        :type products: list[ifcopenshell.entity_instance.entity_instance]
         :param type: Choose from "IfcMaterial", "IfcMaterialConstituentSet",
             "IfcMaterialLayerSet", "IfcMaterialLayerSetUsage",
             "IfcMaterialProfileSet", "IfcMaterialProfileSetUsage", or
@@ -75,8 +75,14 @@ class Usecase:
             If type is Usage then no need to provide `material`, it will be deduced
             from the element type automatically.
         :type material: ifcopenshell.entity_instance.entity_instance, optional
-        :return: The IfcRelAssociatesMaterial entity
-        :rtype: ifcopenshell.entity_instance.entity_instance
+        :return: IfcRelAssociatesMaterial entity
+            or a list of IfcRelAssociatesMaterial entities
+            (possible if `type` is Usage
+            and `products` require different Usages)
+            or `None` if `products` was empty list.
+        :rtype: Union[
+            ifcopenshell.entity_instance.entity_instance,
+            list[ifcopenshell.entity_instance.entity_instance], None]
 
         Example:
 
@@ -89,7 +95,7 @@ class Usecase:
             # material. Let's assign it to the type.
             bench_type = ifcopenshell.api.run("root.create_entity", model, ifc_class="IfcFurnitureType")
             ifcopenshell.api.run("material.assign_material", model,
-                product=bench_type, type="IfcMaterial", material=concrete)
+                products=[bench_type], type="IfcMaterial", material=concrete)
 
             # Let's imagine there are a two occurrences of this bench.  It's not
             # necessary to assign any material to these benches as they
@@ -113,7 +119,7 @@ class Usecase:
 
             # Our wall type now has the layer set assigned to it
             ifcopenshell.api.run("material.assign_material", model,
-                product=wall_type, type="IfcMaterialLayerSet", material=material_set)
+                products=[wall_type], type="IfcMaterialLayerSet", material=material_set)
 
             # Let's imagine an occurrence of this wall type.
             wall = ifcopenshell.api.run("root.create_entity", model, ifc_class="IfcWall")
@@ -125,7 +131,7 @@ class Usecase:
             # they automatically detect the inherited material set from the
             # type. You'd write similar code for a profile set.
             ifcopenshell.api.run("material.assign_material", model,
-                product=wall, type="IfcMaterialLayerSetUsage")
+                products=[wall], type="IfcMaterialLayerSetUsage")
 
             # To be complete, let's create the wall's axis and body
             # representation. Notice how the axis guides the walls "reference
@@ -141,12 +147,19 @@ class Usecase:
             ifcopenshell.api.run("geometry.edit_object_placement", model, product=wall)
         """
         self.file = file
-        self.settings = {"product": product, "type": type, "material": material}
+        self.settings = {"products": products, "type": type, "material": material}
+
+    def execute(self) -> Union[ifcopenshell.entity_instance, list[ifcopenshell.entity_instance], None]:
+        self.products: set[ifcopenshell.entity_instance] = set(self.settings["products"])
+        if not self.products:
+            return
+
+        # NOTE: we always reassign material, even if it might be assigned before
+        for product in self.products:
+            material = ifcopenshell.util.element.get_material(product)
+            if material:
+                ifcopenshell.api.run("material.unassign_material", self.file, product=product)
 
-    def execute(self) -> ifcopenshell.entity_instance:
-        material = ifcopenshell.util.element.get_material(self.settings["product"])
-        if material:
-            ifcopenshell.api.run("material.unassign_material", self.file, product=self.settings["product"])
         if self.settings["type"] == "IfcMaterial" or (
             self.settings["material"] and not self.settings["material"].is_a("IfcMaterial")
         ):
@@ -161,71 +174,104 @@ class Usecase:
             return self.create_material_association(material_set)
 
         elif self.settings["type"] == "IfcMaterialLayerSetUsage":
-            element_type = ifcopenshell.util.element.get_type(self.settings["product"])
-            if element_type:
-                element_type_material = ifcopenshell.util.element.get_material(element_type)
-                if element_type_material and element_type_material.is_a("IfcMaterialLayerSet"):
-                    material_set = element_type_material
+            # NOTE: might return list of rels
+            types_to_products_layers_sets: dict[
+                tuple[Union[ifcopenshell.entity_instance, None], str], tuple[ifcopenshell.entity_instance, list]
+            ] = dict()
+
+            AXIS3_CLASSES = [
+                "IfcSlab",
+                "IfcSlabStandardCase",
+                "IfcSlabElementedCase",
+                "IfcRoof",
+                "IfcRamp",
+                "IfcPlate",
+                "IfcPlateStandardCase",
+            ]
+            for product in self.products:
+                element_type = ifcopenshell.util.element.get_type(product)
+                layer_set_direction = "AXIS3" if product.is_a() in AXIS3_CLASSES else "AXIS2"
+                material_layer_type = (element_type, layer_set_direction)
+
+                if material_layer_type in types_to_products_layers_sets:
+                    types_to_products_layers_sets[material_layer_type][1].append(product)
+                    continue
+
+                if element_type:
+                    element_type_material = ifcopenshell.util.element.get_material(element_type)
+                    if element_type_material and element_type_material.is_a("IfcMaterialLayerSet"):
+                        material_set = element_type_material
+                    else:
+                        material_set = self.file.create_entity("IfcMaterialLayerSet")
                 else:
                     material_set = self.file.create_entity("IfcMaterialLayerSet")
-            else:
-                material_set = self.file.create_entity("IfcMaterialLayerSet")
-            material_set_usage = self.create_layer_set_usage(material_set)
-            return self.create_material_association(material_set_usage)
+                types_to_products_layers_sets[material_layer_type] = (material_set, [product])
+
+            rels = [
+                self.create_layer_set_usage(material_set, layer_set_direction, products)
+                for (_, layer_set_direction), (material_set, products) in types_to_products_layers_sets.items()
+            ]
+            return rels[0] if len(rels) == 1 else rels
 
         elif self.settings["type"] == "IfcMaterialProfileSet":
             material_set = self.file.create_entity(self.settings["type"])
             return self.create_material_association(material_set)
 
         elif self.settings["type"] == "IfcMaterialProfileSetUsage":
-            element_type = ifcopenshell.util.element.get_type(self.settings["product"])
-            if element_type:
-                element_type_material = ifcopenshell.util.element.get_material(element_type)
-                if element_type_material and element_type_material.is_a("IfcMaterialProfileSet"):
-                    material_set = element_type_material
+            # NOTE: might return list of rels
+            types_to_products_profile_sets: dict[
+                Union[ifcopenshell.entity_instance, None], tuple[ifcopenshell.entity_instance, list]
+            ] = dict()
+            for product in self.products:
+                element_type = ifcopenshell.util.element.get_type(product)
+                if element_type in types_to_products_profile_sets:
+                    types_to_products_profile_sets[element_type][1].append(product)
+                    continue
+                if element_type:
+                    element_type_material = ifcopenshell.util.element.get_material(element_type)
+                    if element_type_material and element_type_material.is_a("IfcMaterialProfileSet"):
+                        material_set = element_type_material
+                    else:
+                        material_set = self.file.create_entity("IfcMaterialProfileSet")
                 else:
                     material_set = self.file.create_entity("IfcMaterialProfileSet")
-            else:
-                material_set = self.file.create_entity("IfcMaterialProfileSet")
+                types_to_products_profile_sets[element_type] = (material_set, [product])
 
-            self.update_representation_profile(material_set)
-            material_set_usage = self.create_profile_set_usage(material_set)
-            return self.create_material_association(material_set_usage)
+            rels = []
+            for _, (material_set, products) in types_to_products_profile_sets.items():
+                self.update_representation_profile(material_set, products)
+                material_set_usage = self.create_profile_set_usage(material_set)
+                rels.append(self.create_material_association(material_set_usage, products))
+            return rels[0] if len(rels) == 1 else rels
 
         elif self.settings["type"] == "IfcMaterialList":
             material_set = self.file.create_entity(self.settings["type"])
             material_set.Materials = [self.settings["material"]]
             return self.create_material_association(material_set)
 
-    def update_representation_profile(self, material_set: ifcopenshell.entity_instance) -> None:
+    def update_representation_profile(
+        self, material_set: ifcopenshell.entity_instance, products: list[ifcopenshell.entity_instance]
+    ) -> None:
         profile = material_set.CompositeProfile
         if not profile and material_set.MaterialProfiles:
             profile = material_set.MaterialProfiles[0].Profile
         if not profile:
             return
-        representation = ifcopenshell.util.representation.get_representation(
-            self.settings["product"], "Model", "Body", "MODEL_VIEW"
-        )
-        if not representation:
-            return
-        for subelement in self.file.traverse(representation):
-            if subelement.is_a("IfcSweptAreaSolid"):
-                subelement.SweptArea = profile
+        for product in products:
+            representation = ifcopenshell.util.representation.get_representation(product, "Model", "Body", "MODEL_VIEW")
+            if not representation:
+                return
+            for subelement in self.file.traverse(representation):
+                if subelement.is_a("IfcSweptAreaSolid"):
+                    subelement.SweptArea = profile
 
-    def create_layer_set_usage(self, material_set: ifcopenshell.entity_instance) -> ifcopenshell.entity_instance:
-        if self.settings["product"].is_a() in [
-            "IfcSlab",
-            "IfcSlabStandardCase",
-            "IfcSlabElementedCase",
-            "IfcRoof",
-            "IfcRamp",
-            "IfcPlate",
-            "IfcPlateStandardCase",
-        ]:
-            layer_set_direction = "AXIS3"
-        else:
-            layer_set_direction = "AXIS2"
-        return self.file.create_entity(
+    def create_layer_set_usage(
+        self,
+        material_set: ifcopenshell.entity_instance,
+        layer_set_direction: str,
+        products: list[ifcopenshell.entity_instance],
+    ) -> ifcopenshell.entity_instance:
+        usage = self.file.create_entity(
             "IfcMaterialLayerSetUsage",
             **{
                 "ForLayerSet": material_set,
@@ -234,29 +280,34 @@ class Usecase:
                 "OffsetFromReferenceLine": 0,
             }
         )
+        return self.create_material_association(usage, products)
 
     def create_profile_set_usage(self, material_set: ifcopenshell.entity_instance) -> ifcopenshell.entity_instance:
         return self.file.create_entity("IfcMaterialProfileSetUsage", **{"ForProfileSet": material_set})
 
     def assign_ifc_material(self) -> ifcopenshell.entity_instance:
-        rel = self.get_rel_associates_material(self.settings["material"])
+        material = self.settings["material"] or self.file.create_entity("IfcMaterial")
+        rel = self.get_rel_associates_material(material)
         if not rel:
-            return self.create_material_association(self.settings["material"])
-        related_objects = list(rel.RelatedObjects)
-        related_objects.append(self.settings["product"])
-        rel.RelatedObjects = related_objects
+            return self.create_material_association(material)
+        previous_related_objects = set(rel.RelatedObjects)
+        rel.RelatedObjects = list(previous_related_objects | self.products)
         ifcopenshell.api.run("owner.update_owner_history", self.file, **{"element": rel})
         return rel
 
     def create_material_association(
-        self, relating_material: ifcopenshell.entity_instance
+        self,
+        relating_material: ifcopenshell.entity_instance,
+        products: Optional[list[ifcopenshell.entity_instance]] = None,
     ) -> ifcopenshell.entity_instance:
+        if products is None:
+            products = list(self.products)
         return self.file.create_entity(
             "IfcRelAssociatesMaterial",
             **{
                 "GlobalId": ifcopenshell.guid.new(),
                 "OwnerHistory": ifcopenshell.api.run("owner.create_owner_history", self.file),
-                "RelatedObjects": [self.settings["product"]],
+                "RelatedObjects": products,
                 "RelatingMaterial": relating_material,
             }
         )
@@ -265,11 +316,12 @@ class Usecase:
         self, material: ifcopenshell.entity_instance
     ) -> Union[ifcopenshell.entity_instance, None]:
         if self.file.schema == "IFC2X3" or material.is_a("IfcMaterialList"):
-            rel = [
-                r
-                for r in self.file.by_type("IfcRelAssociatesMaterial")
-                if r.RelatingMaterial == self.settings["material"]
-            ]
-            return rel[0] if rel else None
-        if self.settings["material"].AssociatedTo:
-            return self.settings["material"].AssociatedTo[0]
+            return next(
+                (
+                    r
+                    for r in self.file.by_type("IfcRelAssociatesMaterial")
+                    if r.RelatingMaterial == self.settings["material"]
+                ),
+                None,
+            )
+        return next(iter(material.AssociatedTo), None)

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

@@ -66,12 +66,12 @@ class Usecase:
                 profile_set=material_set, material=steel, profile=hea100)
 
             # Great! Let's assign our material set to our beam type.
-            ifcopenshell.api.run("material.assign_material", model, product=beam_type, material=material_set)
+            ifcopenshell.api.run("material.assign_material", model, products=[beam_type], material=material_set)
 
             # Let's create an occurrence of this beam.
             beam = ifcopenshell.api.run("root.create_entity", model, ifc_class="IfcBeam", name="B1.01")
             ifcopenshell.api.run("material.assign_material", model,
-                product=beam, type="IfcMaterialProfileSetUsage")
+                products=[beam], type="IfcMaterialProfileSetUsage")
 
             # Let's give a 1000mm long beam body representation.
             body = ifcopenshell.api.run("geometry.add_profile_representation",

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

@@ -55,7 +55,7 @@ class Usecase:
 
             # Our wall type now has the layer set assigned to it
             ifcopenshell.api.run("material.assign_material", model,
-                product=wall_type, type="IfcMaterialLayerSet", material=material_set)
+                products=[wall_type], type="IfcMaterialLayerSet", material=material_set)
 
             # Let's imagine an occurrence of this wall type.
             wall = ifcopenshell.api.run("root.create_entity", model, ifc_class="IfcWall")
@@ -67,7 +67,7 @@ class Usecase:
             # they automatically detect the inherited material set from the
             # type. You'd write similar code for a profile set.
             rel = ifcopenshell.api.run("material.assign_material", model,
-                product=wall, type="IfcMaterialLayerSetUsage")
+                products=[wall], type="IfcMaterialLayerSetUsage")
 
             # Let's change the offset from the reference line to be 200mm
             # instead of the default of 0mm.

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

@@ -70,12 +70,12 @@ class Usecase:
                 profile_set=material_set, material=steel, profile=hea100)
 
             # Great! Let's assign our material set to our beam type.
-            ifcopenshell.api.run("material.assign_material", model, product=beam_type, material=material_set)
+            ifcopenshell.api.run("material.assign_material", model, products=[beam_type], material=material_set)
 
             # Let's create an occurrence of this beam.
             beam = ifcopenshell.api.run("root.create_entity", model, ifc_class="IfcBeam", name="B1.01")
             rel = ifcopenshell.api.run("material.assign_material", model,
-                product=beam, type="IfcMaterialProfileSetUsage")
+                products=[beam], type="IfcMaterialProfileSetUsage")
 
             # Let's give a 1000mm long beam body representation.
             body = ifcopenshell.api.run("geometry.add_profile_representation",

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

@@ -44,7 +44,7 @@ class Usecase:
             # Let's imagine a concrete bench made out of concrete.
             bench_type = ifcopenshell.api.run("root.create_entity", model, ifc_class="IfcFurnitureType")
             ifcopenshell.api.run("material.assign_material", model,
-                product=bench_type, type="IfcMaterial", material=concrete)
+                products=[bench_type], type="IfcMaterial", material=concrete)
 
             # Let's change our mind and remove the concrete assignment. The
             # concrete material still exists, but the bench is no longer made

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

@@ -72,7 +72,7 @@ class Usecase:
             wall_type = ifcopenshell.api.run("root.create_entity", library, ifc_class="IfcWallType", name="WAL01")
             concrete = ifcopenshell.api.run("material.add_material", self.file, name="CON", category="concrete")
             rel = ifcopenshell.api.run("material.assign_material", library,
-                product=wall_type, type="IfcMaterialLayerSet")
+                products=[wall_type], type="IfcMaterialLayerSet")
             layer = ifcopenshell.api.run("material.add_layer", library,
                 layer_set=rel.RelatingMaterial, material=concrete)
             layer.Name = "Structure"

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

@@ -65,7 +65,7 @@ class Usecase:
             wall_type = ifcopenshell.api.run("root.create_entity", library, ifc_class="IfcWallType", name="WAL01")
             concrete = ifcopenshell.api.run("material.add_material", self.file, name="CON", category="concrete")
             rel = ifcopenshell.api.run("material.assign_material", library,
-                product=wall_type, type="IfcMaterialLayerSet")
+                products=[wall_type], type="IfcMaterialLayerSet")
             layer = ifcopenshell.api.run("material.add_layer", library,
                 layer_set=rel.RelatingMaterial, material=concrete)
             layer.Name = "Structure"

src/ifcopenshell-python/ifcopenshell/api/style/assign_material_style.py

@@ -82,7 +82,7 @@ class Usecase:
 
             # Assign our concrete material to our wall
             ifcopenshell.api.run("material.assign_material", model,
-                product=wall, type="IfcMaterial", material=concrete)
+                products=[wall], type="IfcMaterial", material=concrete)
 
             # Create a new surface style
             style = ifcopenshell.api.run("style.add_style", model)

src/ifcopenshell-python/ifcopenshell/api/type/assign_type.py

@@ -149,7 +149,7 @@ class Usecase:
             ifcopenshell.api.run("material.edit_layer", model, layer=layer, attributes={"LayerThickness": .013})
 
             # Great! Let's assign our material set to our wall type.
-            ifcopenshell.api.run("material.assign_material", model, product=wall_type, material=material_set)
+            ifcopenshell.api.run("material.assign_material", model, products=[wall_type], material=material_set)
 
             # Now, let's create a wall.
             wall = ifcopenshell.api.run("root.create_entity", model, ifc_class="IfcWall")
@@ -267,10 +267,9 @@ class Usecase:
             return
         ifc_class = type_material.is_a()
         if ifc_class in ("IfcMaterialLayerSet", "IfcMaterialProfileSet"):
-            for related_object in related_objects:
-                ifcopenshell.api.run(
-                    "material.assign_material",
-                    self.file,
-                    product=related_object,
-                    type=f"{ifc_class}Usage",
-                )
+            ifcopenshell.api.run(
+                "material.assign_material",
+                self.file,
+                products=related_objects,
+                type=f"{ifc_class}Usage",
+            )

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

@@ -16,77 +16,209 @@
 # 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 pytest
 import test.bootstrap
 import ifcopenshell.api
 import ifcopenshell.util.element
 
 
-class TestAssignMaterial(test.bootstrap.IFC4):
+class TestAssignMaterialIFC2X3(test.bootstrap.IFC2X3):
     def test_assign_element_single_material(self):
-        element = ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcWall")
+        element1 = ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcWall")
+        element2 = ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcWall")
         material = ifcopenshell.api.run("material.add_material", self.file, name="CON01")
-        ifcopenshell.api.run("material.assign_material", self.file, product=element, type="IfcMaterial", material=material)
+        ifcopenshell.api.run(
+            "material.assign_material", self.file, products=[element1, element2], type="IfcMaterial", material=material
+        )
         assert len(self.file.by_type("IfcRelAssociatesMaterial")) == 1
-        assert element.HasAssociations[0].RelatingMaterial == material
+        assert ifcopenshell.util.element.get_material(element1) == material
+        assert ifcopenshell.util.element.get_material(element2) == material
+
+    def test_raise_exception_creating_ifc_material_without(self):
+        element = ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcWall")
+        ifcopenshell.api.run(
+            "material.assign_material", self.file, products=[element], type="IfcMaterial", material=None
+        )
+        assert ifcopenshell.util.element.get_material(element)
 
     def test_assign_type_single_material(self):
-        element = ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcWallType")
+        element1 = ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcWallType")
+        element2 = ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcWallType")
         material = ifcopenshell.api.run("material.add_material", self.file, name="CON01")
-        ifcopenshell.api.run("material.assign_material", self.file, product=element, type="IfcMaterial", material=material)
+        ifcopenshell.api.run(
+            "material.assign_material", self.file, products=[element1, element2], type="IfcMaterial", material=material
+        )
         assert len(self.file.by_type("IfcRelAssociatesMaterial")) == 1
-        assert element.HasAssociations[0].RelatingMaterial == material
+        assert ifcopenshell.util.element.get_material(element1) == material
+        assert ifcopenshell.util.element.get_material(element2) == material
 
     def test_assign_type_material_layer_set(self):
-        element = ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcWallType")
-        ifcopenshell.api.run("material.assign_material", self.file, product=element, type="IfcMaterialLayerSet")
+        element1 = ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcWallType")
+        element2 = ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcWallType")
+        ifcopenshell.api.run(
+            "material.assign_material", self.file, products=[element1, element2], type="IfcMaterialLayerSet"
+        )
         assert len(self.file.by_type("IfcRelAssociatesMaterial")) == 1
-        material_set = element.HasAssociations[0].RelatingMaterial
+        material_set = ifcopenshell.util.element.get_material(element1)
         assert material_set.is_a("IfcMaterialLayerSet")
         assert not material_set.MaterialLayers
+        assert ifcopenshell.util.element.get_material(element2) == material_set
 
     def test_assign_type_material_layer_set_and_element_layer_set_usage(self):
         element_type = ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcWallType")
-        element = ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcWall")
-        ifcopenshell.api.run("type.assign_type", self.file, related_objects=[element], relating_type=element_type)
-        ifcopenshell.api.run("material.assign_material", self.file, product=element_type, type="IfcMaterialLayerSet")
-        ifcopenshell.api.run("material.assign_material", self.file, product=element, type="IfcMaterialLayerSetUsage")
-        material_set = element_type.HasAssociations[0].RelatingMaterial
-        material_usage = element.HasAssociations[0].RelatingMaterial
-        assert material_usage.is_a("IfcMaterialLayerSetUsage")
-        assert material_usage.ForLayerSet == material_set
+        element1 = ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcWall")
+        element2 = ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcWall")
+        ifcopenshell.api.run(
+            "type.assign_type", self.file, related_objects=[element1, element2], relating_type=element_type
+        )
+        ifcopenshell.api.run("material.assign_material", self.file, products=[element_type], type="IfcMaterialLayerSet")
+        ifcopenshell.api.run(
+            "material.assign_material", self.file, products=[element1, element2], type="IfcMaterialLayerSetUsage"
+        )
+        material_set = ifcopenshell.util.element.get_material(element_type)
+        material_usage1 = ifcopenshell.util.element.get_material(element1, should_inherit=False)
+        assert material_usage1.is_a("IfcMaterialLayerSetUsage")
+        assert material_usage1.ForLayerSet == material_set
+        assert ifcopenshell.util.element.get_material(element2, should_inherit=False) == material_usage1
 
-    def test_assign_type_material_profile_set(self):
-        element = ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcWallType")
-        ifcopenshell.api.run("material.assign_material", self.file, product=element, type="IfcMaterialProfileSet")
+    def test_assign_type_material_layer_set_and_element_layer_set_usage_is_different_for_different_types(self):
+        element_type1 = ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcWallType")
+        element1 = ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcWall")
+        ifcopenshell.api.run("type.assign_type", self.file, related_objects=[element1], relating_type=element_type1)
+        ifcopenshell.api.run(
+            "material.assign_material", self.file, products=[element_type1], type="IfcMaterialLayerSet"
+        )
+
+        element_type2 = ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcWallType")
+        element2 = ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcWall")
+        ifcopenshell.api.run("type.assign_type", self.file, related_objects=[element2], relating_type=element_type2)
+        ifcopenshell.api.run(
+            "material.assign_material", self.file, products=[element_type2], type="IfcMaterialLayerSet"
+        )
+
+        ifcopenshell.api.run(
+            "material.assign_material", self.file, products=[element1, element2], type="IfcMaterialLayerSetUsage"
+        )
+        material_set1 = ifcopenshell.util.element.get_material(element_type1)
+        material_usage1 = ifcopenshell.util.element.get_material(element1, should_inherit=False)
+        assert material_usage1.is_a("IfcMaterialLayerSetUsage")
+        assert material_usage1.ForLayerSet == material_set1
+
+        material_set2 = ifcopenshell.util.element.get_material(element_type2)
+        material_usage2 = ifcopenshell.util.element.get_material(element2, should_inherit=False)
+        assert material_usage2.is_a("IfcMaterialLayerSetUsage")
+        assert material_usage2.ForLayerSet == material_set2
+        assert material_usage2 != material_usage1
+
+    def test_assign_element_layer_set_usage_is_different_for_different_layer_set_directions(self):
+        element1 = ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcWall")
+        element2 = ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcSlab")
+        ifcopenshell.api.run(
+            "material.assign_material", self.file, products=[element1, element2], type="IfcMaterialLayerSetUsage"
+        )
+
+        material_usage1 = ifcopenshell.util.element.get_material(element1, should_inherit=False)
+        assert material_usage1.is_a("IfcMaterialLayerSetUsage")
+        material_set1 = material_usage1.ForLayerSet
+        assert material_set1.is_a("IfcMaterialLayerSet")
+        assert material_usage1.LayerSetDirection == "AXIS2"
+
+        material_usage2 = ifcopenshell.util.element.get_material(element2, should_inherit=False)
+        assert material_usage2.is_a("IfcMaterialLayerSetUsage")
+        material_set2 = material_usage2.ForLayerSet
+        assert material_set2.is_a("IfcMaterialLayerSet")
+        assert material_usage2.LayerSetDirection == "AXIS3"
+
+        assert material_set1 != material_set2
+        assert material_usage1 != material_usage2
+
+    def test_assign_element_material_list(self):
+        element1 = ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcWall")
+        element2 = ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcWall")
+        material = ifcopenshell.api.run("material.add_material", self.file, name="CON01")
+        ifcopenshell.api.run(
+            "material.assign_material",
+            self.file,
+            products=[element1, element2],
+            type="IfcMaterialList",
+            material=material,
+        )
         assert len(self.file.by_type("IfcRelAssociatesMaterial")) == 1
-        material_set = element.HasAssociations[0].RelatingMaterial
+        material_list = ifcopenshell.util.element.get_material(element1)
+        assert material_list.is_a("IfcMaterialList")
+        assert material_list.Materials[0] == material
+        assert ifcopenshell.util.element.get_material(element2) == material_list
+
+
+class TestAssignMaterialIFC4(test.bootstrap.IFC4, TestAssignMaterialIFC2X3):
+    def test_assign_type_material_profile_set(self):
+        element1 = ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcWallType")
+        element2 = ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcWallType")
+        ifcopenshell.api.run(
+            "material.assign_material", self.file, products=[element1, element2], type="IfcMaterialProfileSet"
+        )
+        assert len(self.file.by_type("IfcRelAssociatesMaterial")) == 1
+        material_set = ifcopenshell.util.element.get_material(element1)
         assert material_set.is_a("IfcMaterialProfileSet")
         assert not material_set.MaterialProfiles
+        assert ifcopenshell.util.element.get_material(element2) == material_set
 
     def test_assign_type_material_profile_set_and_element_profile_set_usage(self):
         element_type = ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcWallType")
-        element = ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcWall")
-        ifcopenshell.api.run("type.assign_type", self.file, related_objects=[element], relating_type=element_type)
-        ifcopenshell.api.run("material.assign_material", self.file, product=element_type, type="IfcMaterialProfileSet")
-        ifcopenshell.api.run("material.assign_material", self.file, product=element, type="IfcMaterialProfileSetUsage")
+        element1 = ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcWall")
+        element2 = ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcWall")
+        ifcopenshell.api.run(
+            "type.assign_type", self.file, related_objects=[element1, element2], relating_type=element_type
+        )
+        ifcopenshell.api.run(
+            "material.assign_material", self.file, products=[element_type], type="IfcMaterialProfileSet"
+        )
+        ifcopenshell.api.run(
+            "material.assign_material", self.file, products=[element1, element2], type="IfcMaterialProfileSetUsage"
+        )
         material_set = element_type.HasAssociations[0].RelatingMaterial
-        material_usage = element.HasAssociations[0].RelatingMaterial
-        assert material_usage.is_a("IfcMaterialProfileSetUsage")
-        assert material_usage.ForProfileSet == material_set
+        material_usage1 = element1.HasAssociations[0].RelatingMaterial
+        assert material_usage1.is_a("IfcMaterialProfileSetUsage")
+        assert material_usage1.ForProfileSet == material_set
+        assert ifcopenshell.util.element.get_material(element2, should_inherit=False) == material_usage1
+
+    def test_assign_type_material_profile_set_and_element_profile_set_usage_is_different_for_different_types(self):
+        element_type1 = ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcWallType")
+        element1 = ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcWall")
+        ifcopenshell.api.run("type.assign_type", self.file, related_objects=[element1], relating_type=element_type1)
+        ifcopenshell.api.run(
+            "material.assign_material", self.file, products=[element_type1], type="IfcMaterialProfileSet"
+        )
+
+        element_type2 = ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcWallType")
+        element2 = ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcWall")
+        ifcopenshell.api.run("type.assign_type", self.file, related_objects=[element2], relating_type=element_type2)
+        ifcopenshell.api.run(
+            "material.assign_material", self.file, products=[element_type2], type="IfcMaterialProfileSet"
+        )
+
+        ifcopenshell.api.run(
+            "material.assign_material", self.file, products=[element1, element2], type="IfcMaterialProfileSetUsage"
+        )
+        material_set1 = ifcopenshell.util.element.get_material(element_type1)
+        material_usage1 = ifcopenshell.util.element.get_material(element1, should_inherit=False)
+        assert material_usage1.is_a("IfcMaterialProfileSetUsage")
+        assert material_usage1.ForProfileSet == material_set1
+
+        material_set2 = ifcopenshell.util.element.get_material(element_type2)
+        material_usage2 = ifcopenshell.util.element.get_material(element2, should_inherit=False)
+        assert material_usage2.is_a("IfcMaterialProfileSetUsage")
+        assert material_usage2.ForProfileSet == material_set2
+        assert material_usage2 != material_usage1
 
     def test_assign_type_material_constituent_set(self):
-        element = ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcWallType")
-        ifcopenshell.api.run("material.assign_material", self.file, product=element, type="IfcMaterialConstituentSet")
+        element1 = ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcWallType")
+        element2 = ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcWallType")
+        ifcopenshell.api.run(
+            "material.assign_material", self.file, products=[element1, element2], type="IfcMaterialConstituentSet"
+        )
         assert len(self.file.by_type("IfcRelAssociatesMaterial")) == 1
-        material_set = element.HasAssociations[0].RelatingMaterial
+        material_set = ifcopenshell.util.element.get_material(element1)
         assert material_set.is_a("IfcMaterialConstituentSet")
         assert not material_set.MaterialConstituents
-
-    def test_assign_element_material_list(self):
-        element = ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcWall")
-        material = ifcopenshell.api.run("material.add_material", self.file, name="CON01")
-        ifcopenshell.api.run("material.assign_material", self.file, product=element, type="IfcMaterialList", material=material)
-        assert len(self.file.by_type("IfcRelAssociatesMaterial")) == 1
-        material_list = element.HasAssociations[0].RelatingMaterial
-        assert material_list.is_a("IfcMaterialList")
-        assert material_list.Materials[0] == material
+        assert ifcopenshell.util.element.get_material(element2) == material_set

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

@@ -31,7 +31,7 @@ class TestCopyMaterial(test.bootstrap.IFC4):
     def test_assignments_are_not_copied(self):
         element = ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcWall")
         material = ifcopenshell.api.run("material.add_material", self.file, name="CON01")
-        ifcopenshell.api.run("material.assign_material", self.file, product=element, material=material)
+        ifcopenshell.api.run("material.assign_material", self.file, products=[element], material=material)
         new = ifcopenshell.api.run("material.copy_material", self.file, material=material)
         assert material.AssociatedTo
         assert not new.AssociatedTo

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

@@ -29,7 +29,7 @@ class TestRemoveMaterial(test.bootstrap.IFC4):
     def test_removing_material_with_associations(self):
         wall = ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcWall")
         material = ifcopenshell.api.run("material.add_material", self.file)
-        ifcopenshell.api.run("material.assign_material", self.file, product=wall, material=material)
+        ifcopenshell.api.run("material.assign_material", self.file, products=[wall], material=material)
         ifcopenshell.api.run("material.remove_material", self.file, material=material)
         assert len(self.file.by_type("IfcMaterial")) == 0
         assert len(self.file.by_type("IfcRelAssociatesMaterial")) == 0
@@ -41,7 +41,7 @@ class TestRemoveMaterial(test.bootstrap.IFC4):
             "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.assign_material", self.file, product=wall, material=material_set)
+        ifcopenshell.api.run("material.assign_material", self.file, products=[wall], material=material_set)
         assert len(self.file.by_type("IfcMaterialLayerSet")[0].MaterialLayers) == 1
         ifcopenshell.api.run("material.remove_material", self.file, material=material)
         assert len(self.file.by_type("IfcMaterial")) == 0
@@ -55,7 +55,7 @@ class TestRemoveMaterial(test.bootstrap.IFC4):
             "material.add_material_set", self.file, set_type="IfcMaterialProfileSet"
         )
         ifcopenshell.api.run("material.add_profile", self.file, profile_set=material_set, material=material)
-        ifcopenshell.api.run("material.assign_material", self.file, product=wall, material=material_set)
+        ifcopenshell.api.run("material.assign_material", self.file, products=[wall], material=material_set)
         assert len(self.file.by_type("IfcMaterialProfileSet")[0].MaterialProfiles) == 1
         ifcopenshell.api.run("material.remove_material", self.file, material=material)
         assert len(self.file.by_type("IfcMaterial")) == 0
@@ -69,7 +69,7 @@ class TestRemoveMaterial(test.bootstrap.IFC4):
             "material.add_material_set", self.file, set_type="IfcMaterialConstituentSet"
         )
         ifcopenshell.api.run("material.add_constituent", self.file, constituent_set=material_set, material=material)
-        ifcopenshell.api.run("material.assign_material", self.file, product=wall, material=material_set)
+        ifcopenshell.api.run("material.assign_material", self.file, products=[wall], material=material_set)
         assert len(self.file.by_type("IfcMaterialConstituentSet")[0].MaterialConstituents) == 1
         ifcopenshell.api.run("material.remove_material", self.file, material=material)
         assert len(self.file.by_type("IfcMaterial")) == 0
@@ -83,7 +83,7 @@ class TestRemoveMaterial(test.bootstrap.IFC4):
             "material.add_material_set", self.file, set_type="IfcMaterialList"
         )
         ifcopenshell.api.run("material.add_list_item", self.file, material_list=material_set, material=material)
-        ifcopenshell.api.run("material.assign_material", self.file, product=wall, material=material_set)
+        ifcopenshell.api.run("material.assign_material", self.file, products=[wall], material=material_set)
         assert len(self.file.by_type("IfcMaterialList")[0].Materials) == 1
         ifcopenshell.api.run("material.remove_material", self.file, material=material)
         assert len(self.file.by_type("IfcMaterial")) == 0

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

@@ -29,7 +29,7 @@ class TestRemoveMaterialSet(test.bootstrap.IFC4):
     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.assign_material", self.file, products=[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

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

@@ -26,7 +26,7 @@ class TestUnassignMaterial(test.bootstrap.IFC4):
         element = ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcWall")
         material = ifcopenshell.api.run("material.add_material", self.file, name="CON01")
         ifcopenshell.api.run(
-            "material.assign_material", self.file, product=element, type="IfcMaterial", material=material
+            "material.assign_material", self.file, products=[element], type="IfcMaterial", material=material
         )
         ifcopenshell.api.run("material.unassign_material", self.file, product=element)
         assert len(self.file.by_type("IfcRelAssociatesMaterial")) == 0
@@ -38,10 +38,10 @@ class TestUnassignMaterial(test.bootstrap.IFC4):
         element2 = ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcWall")
         material = ifcopenshell.api.run("material.add_material", self.file, name="CON01")
         ifcopenshell.api.run(
-            "material.assign_material", self.file, product=element1, type="IfcMaterial", material=material
+            "material.assign_material", self.file, products=[element1], type="IfcMaterial", material=material
         )
         ifcopenshell.api.run(
-            "material.assign_material", self.file, product=element2, type="IfcMaterial", material=material
+            "material.assign_material", self.file, products=[element2], type="IfcMaterial", material=material
         )
         ifcopenshell.api.run("material.unassign_material", self.file, product=element2)
         assert element1.HasAssociations
@@ -53,7 +53,7 @@ class TestUnassignMaterial(test.bootstrap.IFC4):
     def test_unassign_material_layer_set_from_type(self):
         element = ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcWallType")
         material = ifcopenshell.api.run("material.add_material", self.file, name="CON01")
-        ifcopenshell.api.run("material.assign_material", self.file, product=element, type="IfcMaterialLayerSet")
+        ifcopenshell.api.run("material.assign_material", self.file, products=[element], type="IfcMaterialLayerSet")
         ifcopenshell.api.run("material.unassign_material", self.file, product=element)
         assert len(self.file.by_type("IfcRelAssociatesMaterial")) == 0
         assert len(self.file.by_type("IfcWallType")) == 1
@@ -64,8 +64,8 @@ class TestUnassignMaterial(test.bootstrap.IFC4):
         element = ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcWall")
         ifcopenshell.api.run("type.assign_type", self.file, related_objects=[element], relating_type=element_type)
         material = ifcopenshell.api.run("material.add_material", self.file, name="CON01")
-        ifcopenshell.api.run("material.assign_material", self.file, product=element_type, type="IfcMaterialLayerSet")
-        ifcopenshell.api.run("material.assign_material", self.file, product=element, type="IfcMaterialLayerSetUsage")
+        ifcopenshell.api.run("material.assign_material", self.file, products=[element_type], type="IfcMaterialLayerSet")
+        ifcopenshell.api.run("material.assign_material", self.file, products=[element], type="IfcMaterialLayerSetUsage")
         ifcopenshell.api.run("material.unassign_material", self.file, product=element)
         assert len(self.file.by_type("IfcRelAssociatesMaterial")) == 1
         assert element_type.HasAssociations
@@ -81,9 +81,9 @@ class TestUnassignMaterial(test.bootstrap.IFC4):
         ifcopenshell.api.run("type.assign_type", self.file, related_objects=[element], relating_type=element_type)
         ifcopenshell.api.run("type.assign_type", self.file, related_objects=[element2], relating_type=element_type)
         material = ifcopenshell.api.run("material.add_material", self.file, name="CON01")
-        ifcopenshell.api.run("material.assign_material", self.file, product=element_type, type="IfcMaterialLayerSet")
+        ifcopenshell.api.run("material.assign_material", self.file, products=[element_type], type="IfcMaterialLayerSet")
         rel = ifcopenshell.api.run(
-            "material.assign_material", self.file, product=element, type="IfcMaterialLayerSetUsage"
+            "material.assign_material", self.file, products=[element], type="IfcMaterialLayerSetUsage"
         )
 
         # In some invalid IFCs from Revit, they reuse usages. Let's recreate this invalid scenario
@@ -105,7 +105,7 @@ class TestUnassignMaterial(test.bootstrap.IFC4):
     def test_unassign_material_profile_set_from_type(self):
         element = ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcWallType")
         material = ifcopenshell.api.run("material.add_material", self.file, name="CON01")
-        ifcopenshell.api.run("material.assign_material", self.file, product=element, type="IfcMaterialProfileSet")
+        ifcopenshell.api.run("material.assign_material", self.file, products=[element], type="IfcMaterialProfileSet")
         ifcopenshell.api.run("material.unassign_material", self.file, product=element)
         assert len(self.file.by_type("IfcRelAssociatesMaterial")) == 0
         assert len(self.file.by_type("IfcWallType")) == 1
@@ -116,8 +116,8 @@ class TestUnassignMaterial(test.bootstrap.IFC4):
         element = ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcWall")
         ifcopenshell.api.run("type.assign_type", self.file, related_objects=[element], relating_type=element_type)
         material = ifcopenshell.api.run("material.add_material", self.file, name="CON01")
-        ifcopenshell.api.run("material.assign_material", self.file, product=element_type, type="IfcMaterialProfileSet")
-        ifcopenshell.api.run("material.assign_material", self.file, product=element, type="IfcMaterialProfileSetUsage")
+        ifcopenshell.api.run("material.assign_material", self.file, products=[element_type], type="IfcMaterialProfileSet")
+        ifcopenshell.api.run("material.assign_material", self.file, products=[element], type="IfcMaterialProfileSetUsage")
         ifcopenshell.api.run("material.unassign_material", self.file, product=element)
         assert len(self.file.by_type("IfcRelAssociatesMaterial")) == 1
         assert element_type.HasAssociations
@@ -129,7 +129,7 @@ class TestUnassignMaterial(test.bootstrap.IFC4):
     def test_unassign_material_constituent_set_from_type(self):
         element = ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcWallType")
         material = ifcopenshell.api.run("material.add_material", self.file, name="CON01")
-        ifcopenshell.api.run("material.assign_material", self.file, product=element, type="IfcMaterialConstituentSet")
+        ifcopenshell.api.run("material.assign_material", self.file, products=[element], type="IfcMaterialConstituentSet")
         ifcopenshell.api.run("material.unassign_material", self.file, product=element)
         assert len(self.file.by_type("IfcRelAssociatesMaterial")) == 0
         assert len(self.file.by_type("IfcWallType")) == 1
@@ -139,7 +139,7 @@ class TestUnassignMaterial(test.bootstrap.IFC4):
         element = ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcWall")
         material = ifcopenshell.api.run("material.add_material", self.file, name="CON01")
         ifcopenshell.api.run(
-            "material.assign_material", self.file, product=element, type="IfcMaterialList", material=material
+            "material.assign_material", self.file, products=[element], type="IfcMaterialList", material=material
         )
         ifcopenshell.api.run("material.unassign_material", self.file, product=element)
         assert len(self.file.by_type("IfcRelAssociatesMaterial")) == 0

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

@@ -70,8 +70,8 @@ class TestAppendAsset(test.bootstrap.IFC4):
         element = ifcopenshell.api.run("root.create_entity", library, ifc_class="IfcWallType")
         element2 = ifcopenshell.api.run("root.create_entity", library, ifc_class="IfcWallType")
         material = ifcopenshell.api.run("material.add_material", library, name="Material")
-        ifcopenshell.api.run("material.assign_material", library, product=element, material=material)
-        ifcopenshell.api.run("material.assign_material", library, product=element2, material=material)
+        ifcopenshell.api.run("material.assign_material", library, products=[element], material=material)
+        ifcopenshell.api.run("material.assign_material", library, products=[element2], material=material)
         ifcopenshell.api.run("project.append_asset", self.file, library=library, element=element)
         assert len(self.file.by_type("IfcWallType")) == 1
 
@@ -79,7 +79,7 @@ class TestAppendAsset(test.bootstrap.IFC4):
         library = ifcopenshell.api.run("project.create_file")
         element = ifcopenshell.api.run("root.create_entity", library, ifc_class="IfcWallType")
         material = ifcopenshell.api.run("material.add_material", library, name="Material")
-        ifcopenshell.api.run("material.assign_material", library, product=element, material=material)
+        ifcopenshell.api.run("material.assign_material", library, products=[element], material=material)
         ifcopenshell.api.run("project.append_asset", self.file, library=library, element=element)
         assert self.file.by_type("IfcWallType")[0].HasAssociations[0].RelatingMaterial.Name == "Material"
 
@@ -90,9 +90,9 @@ class TestAppendAsset(test.bootstrap.IFC4):
         element_type2 = ifcopenshell.api.run("root.create_entity", library, ifc_class="IfcWallType")
         ifcopenshell.api.run("type.assign_type", library, related_objects=[element], relating_type=element_type)
         material = ifcopenshell.api.run("material.add_material", library, name="Material")
-        ifcopenshell.api.run("material.assign_material", library, product=element, material=material)
-        ifcopenshell.api.run("material.assign_material", library, product=element_type, material=material)
-        ifcopenshell.api.run("material.assign_material", library, product=element_type2, material=material)
+        ifcopenshell.api.run("material.assign_material", library, products=[element], material=material)
+        ifcopenshell.api.run("material.assign_material", library, products=[element_type], material=material)
+        ifcopenshell.api.run("material.assign_material", library, products=[element_type2], material=material)
 
         # appending another type not connected to IfcWall directly
         ifcopenshell.api.run("project.append_asset", self.file, library=library, element=element_type2)
@@ -111,8 +111,8 @@ class TestAppendAsset(test.bootstrap.IFC4):
         pset = ifcopenshell.api.run("pset.add_pset", library, product=material, name="Foo_Bar")
         ifcopenshell.api.run("pset.edit_pset", library, pset=pset, properties={"Foo": "Bar"})
 
-        ifcopenshell.api.run("material.assign_material", library, product=element1, material=material)
-        ifcopenshell.api.run("material.assign_material", library, product=element2, material=material)
+        ifcopenshell.api.run("material.assign_material", library, products=[element1], material=material)
+        ifcopenshell.api.run("material.assign_material", library, products=[element2], material=material)
         new1 = ifcopenshell.api.run("project.append_asset", self.file, library=library, element=element1)
         new2 = ifcopenshell.api.run("project.append_asset", self.file, library=library, element=element2)
 
@@ -139,8 +139,8 @@ class TestAppendAsset(test.bootstrap.IFC4):
         ifcopenshell.api.run("material.add_layer", library, layer_set=layer_set2, material=material)
         ifcopenshell.api.run("material.add_layer", library, layer_set=layer_set2, material=material)
 
-        ifcopenshell.api.run("material.assign_material", library, product=element1, material=layer_set1)
-        ifcopenshell.api.run("material.assign_material", library, product=element2, material=layer_set2)
+        ifcopenshell.api.run("material.assign_material", library, products=[element1], material=layer_set1)
+        ifcopenshell.api.run("material.assign_material", library, products=[element2], material=layer_set2)
 
         new1 = ifcopenshell.api.run("project.append_asset", self.file, library=library, element=element1)
         new2 = ifcopenshell.api.run("project.append_asset", self.file, library=library, element=element2)
@@ -160,7 +160,7 @@ class TestAppendAsset(test.bootstrap.IFC4):
         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)
+        rel = ifcopenshell.api.run("material.assign_material", library, products=[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.
@@ -201,7 +201,7 @@ class TestAppendAsset(test.bootstrap.IFC4):
 
         element = ifcopenshell.api.run("root.create_entity", library, ifc_class="IfcWallType")
         material = ifcopenshell.api.run("material.add_material", library, name="Material")
-        ifcopenshell.api.run("material.assign_material", library, product=element, material=material)
+        ifcopenshell.api.run("material.assign_material", library, products=[element], material=material)
         style = ifcopenshell.api.run("style.add_style", library)
         ifcopenshell.api.run("style.assign_material_style", library, material=material, style=style, context=context)
         ifcopenshell.api.run("project.append_asset", self.file, library=library, element=element)
@@ -378,7 +378,7 @@ class TestAppendAsset(test.bootstrap.IFC4):
         library = ifcopenshell.api.run("project.create_file")
         element = ifcopenshell.api.run("root.create_entity", library, ifc_class="IfcWall")
         material = ifcopenshell.api.run("material.add_material", library, name="Material")
-        ifcopenshell.api.run("material.assign_material", library, product=element, material=material)
+        ifcopenshell.api.run("material.assign_material", library, products=[element], material=material)
         ifcopenshell.api.run("project.append_asset", self.file, library=library, element=element)
         assert ifcopenshell.util.element.get_material(self.file.by_type("IfcWall")[0]).Name == "Material"
 
@@ -389,9 +389,9 @@ class TestAppendAsset(test.bootstrap.IFC4):
         element_type2 = ifcopenshell.api.run("root.create_entity", library, ifc_class="IfcWallType")
         ifcopenshell.api.run("type.assign_type", library, related_objects=[element], relating_type=element_type)
         material = ifcopenshell.api.run("material.add_material", library, name="Material")
-        ifcopenshell.api.run("material.assign_material", library, product=element, material=material)
-        ifcopenshell.api.run("material.assign_material", library, product=element_type, material=material)
-        ifcopenshell.api.run("material.assign_material", library, product=element_type2, material=material)
+        ifcopenshell.api.run("material.assign_material", library, products=[element], material=material)
+        ifcopenshell.api.run("material.assign_material", library, products=[element_type], material=material)
+        ifcopenshell.api.run("material.assign_material", library, products=[element_type2], material=material)
         ifcopenshell.api.run("project.append_asset", self.file, library=library, element=element)
         assert [e.GlobalId for e in self.file.by_type("IfcWallType")] == [element_type.GlobalId]
 

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

@@ -369,7 +369,7 @@ class TestRemoveProduct(test.bootstrap.IFC4):
     def test_removing_all_material_relationships_of_an_element(self):
         element = ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcWall")
         material = ifcopenshell.api.run("material.add_material", self.file, name="Foo")
-        ifcopenshell.api.run("material.assign_material", self.file, product=element, material=material)
+        ifcopenshell.api.run("material.assign_material", self.file, products=[element], material=material)
         ifcopenshell.api.run("root.remove_product", self.file, product=element)
         assert not self.file.by_type("IfcRelAssociatesMaterial")
         assert self.file.by_type("IfcMaterial")

src/ifcopenshell-python/test/api/style/test_assign_material_style.py

@@ -75,7 +75,7 @@ class TestAssignMaterialStyle(test.bootstrap.IFC4):
             "material.add_constituent", self.file, constituent_set=material_set, material=material
         )
         constituent.Name = name
-        ifcopenshell.api.run("material.assign_material", self.file, product=element, material=material_set)
+        ifcopenshell.api.run("material.assign_material", self.file, products=[element], material=material_set)
 
         ifcopenshell.api.run("style.assign_material_style", self.file, material=material, style=style, context=context)
 

src/ifcopenshell-python/test/api/style/test_unassign_material_style.py

@@ -71,7 +71,7 @@ class TestAssignMaterialStyle(test.bootstrap.IFC4):
             "material.add_constituent", self.file, constituent_set=material_set, material=material
         )
         constituent.Name = name
-        ifcopenshell.api.run("material.assign_material", self.file, product=element, material=material_set)
+        ifcopenshell.api.run("material.assign_material", self.file, products=[element], material=material_set)
 
         ifcopenshell.api.run("style.assign_material_style", self.file, material=material, style=style, context=context)
         ifcopenshell.api.run(

src/ifcopenshell-python/test/api/test_api.py

@@ -164,3 +164,13 @@ class TestTemporarySupportForDeprecatedAPIArguments(test.bootstrap.IFC4):
 
         ifcopenshell.api.run("system.unassign_system", self.file, product=element2, system=system)
         assert ifcopenshell.util.system.get_system_elements(system) == []
+
+    @deprecation_check
+    def test_assign_element_single_material(self):
+        element = ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcWall")
+        material = ifcopenshell.api.run("material.add_material", self.file, name="CON01")
+        ifcopenshell.api.run(
+            "material.assign_material", self.file, product=element, type="IfcMaterial", material=material
+        )
+        assert len(self.file.by_type("IfcRelAssociatesMaterial")) == 1
+        assert element.HasAssociations[0].RelatingMaterial == material

src/ifcopenshell-python/test/api/type/test_assign_type.py

@@ -71,7 +71,7 @@ class TestAssignType(test.bootstrap.IFC4):
         context = self.file.createIfcGeometricRepresentationContext()
         rep = self.file.createIfcShapeRepresentation(ContextOfItems=context)
         ifcopenshell.api.run("geometry.assign_representation", self.file, product=element_type, representation=rep)
-        ifcopenshell.api.run("material.assign_material", self.file, product=element_type, type="IfcMaterialLayerSet")
+        ifcopenshell.api.run("material.assign_material", self.file, products=[element_type], type="IfcMaterialLayerSet")
 
         element = ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcWall")
         ifcopenshell.api.run(
@@ -120,7 +120,7 @@ class TestAssignType(test.bootstrap.IFC4):
             material_types += ("IfcMaterialProfileSet",)
         for material_type in material_types:
             element_type = ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcWallType")
-            ifcopenshell.api.run("material.assign_material", self.file, product=element_type, type=material_type)
+            ifcopenshell.api.run("material.assign_material", self.file, products=[element_type], type=material_type)
             element = ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcWall")
             ifcopenshell.api.run("type.assign_type", self.file, related_objects=[element], relating_type=element_type)
             material = ifcopenshell.util.element.get_material(element)
@@ -130,7 +130,7 @@ class TestAssignType(test.bootstrap.IFC4):
     def test_do_not_reassign_material_if_it_was_assigned_previously(self):
         element1 = ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcWall")
         element_type = ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcWallType")
-        ifcopenshell.api.run("material.assign_material", self.file, product=element_type, type="IfcMaterialLayerSet")
+        ifcopenshell.api.run("material.assign_material", self.file, products=[element_type], type="IfcMaterialLayerSet")
         ifcopenshell.api.run("type.assign_type", self.file, related_objects=[element1], relating_type=element_type)
         assert (material := ifcopenshell.util.element.get_material(element1))
         material_id = material.id()

src/ifcopenshell-python/test/api/type/test_unassign_type.py

@@ -48,7 +48,7 @@ class TestUnassignType(test.bootstrap.IFC4):
         context = self.file.createIfcGeometricRepresentationContext()
         rep = self.file.createIfcShapeRepresentation(ContextOfItems=context)
         ifcopenshell.api.run("geometry.assign_representation", self.file, product=element_type, representation=rep)
-        ifcopenshell.api.run("material.assign_material", self.file, product=element_type, type="IfcMaterialLayerSet")
+        ifcopenshell.api.run("material.assign_material", self.file, products=[element_type], type="IfcMaterialLayerSet")
 
         element = ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcWall")
         ifcopenshell.api.run("type.assign_type", self.file, related_objects=[element], relating_type=element_type)

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

@@ -339,52 +339,52 @@ class TestGetMaterial(test.bootstrap.IFC4):
     def test_getting_the_material_of_a_product(self):
         element = ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcWall")
         material = ifcopenshell.api.run("material.add_material", self.file)
-        ifcopenshell.api.run("material.assign_material", self.file, product=element, material=material)
+        ifcopenshell.api.run("material.assign_material", self.file, products=[element], material=material)
         assert subject.get_material(element) == material
 
     def test_getting_a_material_list_of_a_product(self):
         element = ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcWall")
         material = ifcopenshell.api.run("material.add_material", self.file)
         rel = ifcopenshell.api.run(
-            "material.assign_material", self.file, product=element, type="IfcMaterialList", material=material
+            "material.assign_material", self.file, products=[element], type="IfcMaterialList", material=material
         )
         assert subject.get_material(element) == rel.RelatingMaterial
 
     def test_getting_a_material_layer_set_of_a_product(self):
         element = ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcWall")
-        rel = ifcopenshell.api.run("material.assign_material", self.file, product=element, type="IfcMaterialLayerSet")
+        rel = ifcopenshell.api.run("material.assign_material", self.file, products=[element], type="IfcMaterialLayerSet")
         assert subject.get_material(element) == rel.RelatingMaterial
 
     def test_getting_a_material_profile_set_of_a_product(self):
         element = ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcWall")
-        rel = ifcopenshell.api.run("material.assign_material", self.file, product=element, type="IfcMaterialProfileSet")
+        rel = ifcopenshell.api.run("material.assign_material", self.file, products=[element], type="IfcMaterialProfileSet")
         assert subject.get_material(element) == rel.RelatingMaterial
 
     def test_getting_a_material_layer_set_usage_of_a_product(self):
         element = ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcWall")
         rel = ifcopenshell.api.run(
-            "material.assign_material", self.file, product=element, type="IfcMaterialLayerSetUsage"
+            "material.assign_material", self.file, products=[element], type="IfcMaterialLayerSetUsage"
         )
         assert subject.get_material(element) == rel.RelatingMaterial
 
     def test_getting_a_material_profile_set_usage_of_a_product(self):
         element = ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcWall")
         rel = ifcopenshell.api.run(
-            "material.assign_material", self.file, product=element, type="IfcMaterialProfileSetUsage"
+            "material.assign_material", self.file, products=[element], type="IfcMaterialProfileSetUsage"
         )
         assert subject.get_material(element) == rel.RelatingMaterial
 
     def test_getting_a_material_layer_set_indirectly_from_an_assigned_usage(self):
         element = ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcWall")
         rel = ifcopenshell.api.run(
-            "material.assign_material", self.file, product=element, type="IfcMaterialLayerSetUsage"
+            "material.assign_material", self.file, products=[element], type="IfcMaterialLayerSetUsage"
         )
         assert subject.get_material(element, should_skip_usage=True) == rel.RelatingMaterial.ForLayerSet
 
     def test_getting_a_material_profile_set_indirectly_from_an_assigned_usage(self):
         element = ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcWall")
         rel = ifcopenshell.api.run(
-            "material.assign_material", self.file, product=element, type="IfcMaterialProfileSetUsage"
+            "material.assign_material", self.file, products=[element], type="IfcMaterialProfileSetUsage"
         )
         assert subject.get_material(element, should_skip_usage=True) == rel.RelatingMaterial.ForProfileSet
 
@@ -393,7 +393,7 @@ class TestGetMaterial(test.bootstrap.IFC4):
         element_type = ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcWallType")
         ifcopenshell.api.run("type.assign_type", self.file, related_objects=[element], relating_type=element_type)
         material = ifcopenshell.api.run("material.add_material", self.file)
-        ifcopenshell.api.run("material.assign_material", self.file, product=element_type, material=material)
+        ifcopenshell.api.run("material.assign_material", self.file, products=[element_type], material=material)
         assert subject.get_material(element) == material
 
     def test_getting_an_overridden_material_from_the_elements_occurrence(self):
@@ -401,9 +401,9 @@ class TestGetMaterial(test.bootstrap.IFC4):
         element_type = ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcWallType")
         ifcopenshell.api.run("type.assign_type", self.file, related_objects=[element], relating_type=element_type)
         material = ifcopenshell.api.run("material.add_material", self.file)
-        ifcopenshell.api.run("material.assign_material", self.file, product=element_type, material=material)
+        ifcopenshell.api.run("material.assign_material", self.file, products=[element_type], material=material)
         material = ifcopenshell.api.run("material.add_material", self.file)
-        ifcopenshell.api.run("material.assign_material", self.file, product=element, material=material)
+        ifcopenshell.api.run("material.assign_material", self.file, products=[element], material=material)
         assert subject.get_material(element) == material
 
     def test_getting_direct_materials_without_checking_inheritance(self):
@@ -411,7 +411,7 @@ class TestGetMaterial(test.bootstrap.IFC4):
         element_type = ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcWallType")
         ifcopenshell.api.run("type.assign_type", self.file, related_objects=[element], relating_type=element_type)
         material = ifcopenshell.api.run("material.add_material", self.file)
-        ifcopenshell.api.run("material.assign_material", self.file, product=element_type, material=material)
+        ifcopenshell.api.run("material.assign_material", self.file, products=[element_type], material=material)
         assert subject.get_material(element, should_inherit=False) is None
 
 
@@ -419,7 +419,7 @@ class TestGetMaterials(test.bootstrap.IFC4):
     def test_getting_the_materials_of_a_product(self):
         element = ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcWall")
         material = ifcopenshell.api.run("material.add_material", self.file)
-        ifcopenshell.api.run("material.assign_material", self.file, product=element, material=material)
+        ifcopenshell.api.run("material.assign_material", self.file, products=[element], material=material)
         assert subject.get_materials(element) == [material]
 
 
@@ -440,7 +440,7 @@ class TestGetStyles(test.bootstrap.IFC4):
         )
 
         material = ifcopenshell.api.run("material.add_material", self.file)
-        ifcopenshell.api.run("material.assign_material", self.file, product=element, material=material)
+        ifcopenshell.api.run("material.assign_material", self.file, products=[element], material=material)
 
         style = ifcopenshell.api.run("style.add_style", self.file)
         ifcopenshell.api.run(
@@ -487,7 +487,7 @@ class TestGetElementsByMaterial(test.bootstrap.IFC4):
     def test_getting_elements_of_a_material(self):
         element = ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcWall")
         material = ifcopenshell.api.run("material.add_material", self.file)
-        ifcopenshell.api.run("material.assign_material", self.file, product=element, material=material)
+        ifcopenshell.api.run("material.assign_material", self.file, products=[element], material=material)
         assert subject.get_elements_by_material(self.file, material) == {element}
 
     def test_getting_elements_of_a_material_layer_set(self):
@@ -497,8 +497,8 @@ class TestGetElementsByMaterial(test.bootstrap.IFC4):
         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.assign_material", self.file, product=element_type, material=material_set)
-        ifcopenshell.api.run("material.assign_material", self.file, product=element, type="IfcMaterialLayerSetUsage")
+        ifcopenshell.api.run("material.assign_material", self.file, products=[element_type], material=material_set)
+        ifcopenshell.api.run("material.assign_material", self.file, products=[element], type="IfcMaterialLayerSetUsage")
         usage = self.file.by_type("IfcMaterialLayerSetUsage")[0]
         assert subject.get_elements_by_material(self.file, material) == {element, element_type}
         assert subject.get_elements_by_material(self.file, material_set) == {element, element_type}
@@ -511,8 +511,8 @@ class TestGetElementsByMaterial(test.bootstrap.IFC4):
         material = ifcopenshell.api.run("material.add_material", self.file)
         material_set = ifcopenshell.api.run("material.add_material_set", self.file, set_type="IfcMaterialProfileSet")
         ifcopenshell.api.run("material.add_profile", self.file, profile_set=material_set, material=material)
-        ifcopenshell.api.run("material.assign_material", self.file, product=element_type, material=material_set)
-        ifcopenshell.api.run("material.assign_material", self.file, product=element, type="IfcMaterialProfileSetUsage")
+        ifcopenshell.api.run("material.assign_material", self.file, products=[element_type], material=material_set)
+        ifcopenshell.api.run("material.assign_material", self.file, products=[element], type="IfcMaterialProfileSetUsage")
         usage = self.file.by_type("IfcMaterialProfileSetUsage")[0]
         assert subject.get_elements_by_material(self.file, material) == {element, element_type}
         assert subject.get_elements_by_material(self.file, material_set) == {element, element_type}
@@ -525,7 +525,7 @@ class TestGetElementsByMaterial(test.bootstrap.IFC4):
             "material.add_material_set", self.file, set_type="IfcMaterialConstituentSet"
         )
         ifcopenshell.api.run("material.add_constituent", self.file, constituent_set=material_set, material=material)
-        ifcopenshell.api.run("material.assign_material", self.file, product=element, material=material_set)
+        ifcopenshell.api.run("material.assign_material", self.file, products=[element], material=material_set)
         assert subject.get_elements_by_material(self.file, material) == {element}
         assert subject.get_elements_by_material(self.file, material_set) == {element}
 
@@ -534,7 +534,7 @@ class TestGetElementsByMaterial(test.bootstrap.IFC4):
         material = ifcopenshell.api.run("material.add_material", self.file)
         material_set = ifcopenshell.api.run("material.add_material_set", self.file, set_type="IfcMaterialList")
         ifcopenshell.api.run("material.add_list_item", self.file, material_list=material_set, material=material)
-        ifcopenshell.api.run("material.assign_material", self.file, product=element, material=material_set)
+        ifcopenshell.api.run("material.assign_material", self.file, products=[element], material=material_set)
         assert subject.get_elements_by_material(self.file, material) == {element}
         assert subject.get_elements_by_material(self.file, material_set) == {element}
 
@@ -585,7 +585,7 @@ class TestGetElementsByStyle(test.bootstrap.IFC4):
     def test_getting_elements_of_a_styled_material(self):
         element = self.file.createIfcWall()
         material = ifcopenshell.api.run("material.add_material", self.file)
-        ifcopenshell.api.run("material.assign_material", self.file, product=element, material=material)
+        ifcopenshell.api.run("material.assign_material", self.file, products=[element], material=material)
         style = self.file.createIfcSurfaceStyle()
         self.file.createIfcMaterialDefinitionRepresentation(
             RepresentedMaterial=material,

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

@@ -85,7 +85,7 @@ class TestGetElementValue(test.bootstrap.IFC4):
         layer = ifcopenshell.api.run("material.add_layer", self.file, layer_set=material_set, material=material)
         layer.Name = "L2"
         ifcopenshell.api.run("material.edit_layer", self.file, layer=layer, attributes={"LayerThickness": 13})
-        ifcopenshell.api.run("material.assign_material", self.file, product=element, material=material_set)
+        ifcopenshell.api.run("material.assign_material", self.file, products=[element], material=material_set)
         assert subject.get_element_value(element, "material.MaterialLayers.Name") == ["L1", "L2"]
         # Allow to use "item" to generically select an item in a material set
         assert subject.get_element_value(element, "material.item.Name") == ["L1", "L2"]
@@ -109,7 +109,7 @@ class TestGetElementValue(test.bootstrap.IFC4):
         )
         layer = ifcopenshell.api.run("material.add_layer", self.file, layer_set=material_set, material=material)
         layer.Name = "L1"
-        ifcopenshell.api.run("material.assign_material", self.file, product=element, material=material_set)
+        ifcopenshell.api.run("material.assign_material", self.file, products=[element], material=material_set)
         assert subject.get_element_value(element, "material.item.Name.0") == "L1"
         assert subject.get_element_value(element, "material.item.Name.1") is None
 
@@ -180,7 +180,7 @@ class TestFilterElements(test.bootstrap.IFC4):
         element2 = ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcWall")
         assert subject.filter_elements(self.file, "IfcWall, material=NULL") == {element, element2}
         material = ifcopenshell.api.run("material.add_material", self.file, name="CON01")
-        ifcopenshell.api.run("material.assign_material", self.file, product=element, material=material)
+        ifcopenshell.api.run("material.assign_material", self.file, products=[element], material=material)
         assert subject.filter_elements(self.file, "IfcWall, material=CON01") == {element}
         assert subject.filter_elements(self.file, "IfcWall, material!=CON01") == {element2}
 
@@ -511,7 +511,7 @@ class TestSelector(test.bootstrap.IFC4):
     def test_selecting_via_a_material(self):
         element = ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcWall")
         material = ifcopenshell.api.run("material.add_material", self.file, name="CON01")
-        ifcopenshell.api.run("material.assign_material", self.file, product=element, material=material)
+        ifcopenshell.api.run("material.assign_material", self.file, products=[element], material=material)
         assert set(subject.Selector.parse(self.file, '.IfcWall[material.Name="CON01"]')) == {element}
 
     def test_selecting_via_a_material_set(self):
@@ -522,7 +522,7 @@ class TestSelector(test.bootstrap.IFC4):
         )
         layer = ifcopenshell.api.run("material.add_layer", self.file, layer_set=material_set, material=material)
         ifcopenshell.api.run("material.edit_layer", self.file, layer=layer, attributes={"LayerThickness": 13})
-        ifcopenshell.api.run("material.assign_material", self.file, product=element, material=material_set)
+        ifcopenshell.api.run("material.assign_material", self.file, products=[element], material=material_set)
         assert set(subject.Selector.parse(self.file, '.IfcWall[material.LayerSetName="FOO"]')) == {element}
 
     def test_selecting_via_a_material_set_item(self):
@@ -534,7 +534,7 @@ class TestSelector(test.bootstrap.IFC4):
         )
         layer = ifcopenshell.api.run("material.add_layer", self.file, layer_set=material_set, material=material)
         layer = ifcopenshell.api.run("material.add_layer", self.file, layer_set=material_set, material=material2)
-        ifcopenshell.api.run("material.assign_material", self.file, product=element, material=material_set)
+        ifcopenshell.api.run("material.assign_material", self.file, products=[element], material=material_set)
         assert set(subject.Selector.parse(self.file, '.IfcWall[material.item.Material.Name="CON01"]')) == {element}
         assert set(subject.Selector.parse(self.file, '.IfcWall[material.item.Material.Name="CON02"]')) == {element}
         assert set(subject.Selector.parse(self.file, '.IfcWall[material.item.Material.Name="CON03"]')) == set()

src/ifcpatch/test/test_MergeDuplicateTypes.py

@@ -34,7 +34,7 @@ class TestMergeDuplicateTypes(test.bootstrap.IFC4):
         wall_type1 = ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcWallType", name="WallType")
         rep = self.file.createIfcShapeRepresentation(ContextOfItems=context)
         ifcopenshell.api.run("geometry.assign_representation", self.file, product=wall_type1, representation=rep)
-        ifcopenshell.api.run("material.assign_material", self.file, product=wall_type1, type="IfcMaterialLayerSet")
+        ifcopenshell.api.run("material.assign_material", self.file, products=[wall_type1], type="IfcMaterialLayerSet")
         ifcopenshell.api.run(
             "type.assign_type",
             self.file,
@@ -47,7 +47,7 @@ class TestMergeDuplicateTypes(test.bootstrap.IFC4):
         wall_type2 = ifcopenshell.api.run("root.create_entity", self.file, ifc_class="IfcWallType", name="WallType")
         rep = self.file.createIfcShapeRepresentation(ContextOfItems=context)
         ifcopenshell.api.run("geometry.assign_representation", self.file, product=wall_type2, representation=rep)
-        ifcopenshell.api.run("material.assign_material", self.file, product=wall_type2, type="IfcMaterialLayerSet")
+        ifcopenshell.api.run("material.assign_material", self.file, products=[wall_type2], type="IfcMaterialLayerSet")
         ifcopenshell.api.run(
             "type.assign_type",
             self.file,

src/ifctester/test/test_facet.py

@@ -1260,7 +1260,7 @@ class TestMaterial:
         element = ifcopenshell.api.run("root.create_entity", ifc, ifc_class="IfcWall")
         run("Elements without a material always fail", facet=facet, inst=element, expected=False)
         material = ifcopenshell.api.run("material.add_material", ifc)
-        ifcopenshell.api.run("material.assign_material", ifc, product=element, material=material)
+        ifcopenshell.api.run("material.assign_material", ifc, products=[element], material=material)
         run("Elements with any material will pass an empty material facet", facet=facet, inst=element, expected=True)
 
         run("A required facet checks all parameters as normal", facet=facet, inst=element, expected=True)
@@ -1275,7 +1275,7 @@ class TestMaterial:
         facet = Material(value="Foo")
         element = ifcopenshell.api.run("root.create_entity", ifc, ifc_class="IfcWall")
         material = ifcopenshell.api.run("material.add_material", ifc)
-        ifcopenshell.api.run("material.assign_material", ifc, product=element, material=material)
+        ifcopenshell.api.run("material.assign_material", ifc, products=[element], material=material)
         material.Name = "Foo"
         run("A material name may pass the value check", facet=facet, inst=element, expected=True)
         material.Name = "Bar"
@@ -1286,7 +1286,7 @@ class TestMaterial:
         facet = Material(value="Foo")
         element = ifcopenshell.api.run("root.create_entity", ifc, ifc_class="IfcWall")
         material_set = ifcopenshell.api.run("material.add_material_set", ifc, set_type="IfcMaterialList")
-        ifcopenshell.api.run("material.assign_material", ifc, product=element, material=material_set)
+        ifcopenshell.api.run("material.assign_material", ifc, products=[element], material=material_set)
         material = ifcopenshell.api.run("material.add_material", ifc)
         ifcopenshell.api.run("material.add_list_item", ifc, material_list=material_set, material=material)
         material.Name = "Foo"
@@ -1299,7 +1299,7 @@ class TestMaterial:
         facet = Material(value="Foo")
         element = ifcopenshell.api.run("root.create_entity", ifc, ifc_class="IfcWall")
         material_set = ifcopenshell.api.run("material.add_material_set", ifc, set_type="IfcMaterialLayerSet")
-        ifcopenshell.api.run("material.assign_material", ifc, product=element, material=material_set)
+        ifcopenshell.api.run("material.assign_material", ifc, products=[element], material=material_set)
         material = ifcopenshell.api.run("material.add_material", ifc)
         layer = ifcopenshell.api.run("material.add_layer", ifc, layer_set=material_set, material=material)
         layer.Name = "Foo"
@@ -1318,7 +1318,7 @@ class TestMaterial:
         facet = Material(value="Foo")
         element = ifcopenshell.api.run("root.create_entity", ifc, ifc_class="IfcWall")
         material_set = ifcopenshell.api.run("material.add_material_set", ifc, set_type="IfcMaterialProfileSet")
-        ifcopenshell.api.run("material.assign_material", ifc, product=element, material=material_set)
+        ifcopenshell.api.run("material.assign_material", ifc, products=[element], material=material_set)
         material = ifcopenshell.api.run("material.add_material", ifc)
         profile = ifcopenshell.api.run("material.add_profile", ifc, profile_set=material_set, material=material)
         profile.Name = "Foo"
@@ -1338,7 +1338,7 @@ class TestMaterial:
         facet = Material(value="Foo")
         element = ifcopenshell.api.run("root.create_entity", ifc, ifc_class="IfcWall")
         material_set = ifcopenshell.api.run("material.add_material_set", ifc, set_type="IfcMaterialConstituentSet")
-        ifcopenshell.api.run("material.assign_material", ifc, product=element, material=material_set)
+        ifcopenshell.api.run("material.assign_material", ifc, products=[element], material=material_set)
         run("A constituent set with no data will fail a value check", facet=facet, inst=element, expected=False)
         material = ifcopenshell.api.run("material.add_material", ifc)
         constituent = ifcopenshell.api.run(
@@ -1376,7 +1376,7 @@ class TestMaterial:
         element_type = ifcopenshell.api.run("root.create_entity", ifc, ifc_class="IfcWallType")
         ifcopenshell.api.run("type.assign_type", ifc, related_objects=[element], relating_type=element_type)
         material = ifcopenshell.api.run("material.add_material", ifc)
-        ifcopenshell.api.run("material.assign_material", ifc, product=element_type, material=material)
+        ifcopenshell.api.run("material.assign_material", ifc, products=[element_type], material=material)
         material.Name = "Foo"
         facet = Material(value="Foo")
         run("Occurrences can inherit materials from their types", facet=facet, inst=element, expected=True)
@@ -1386,10 +1386,10 @@ class TestMaterial:
         element_type = ifcopenshell.api.run("root.create_entity", ifc, ifc_class="IfcWallType")
         ifcopenshell.api.run("type.assign_type", ifc, related_objects=[element], relating_type=element_type)
         material = ifcopenshell.api.run("material.add_material", ifc)
-        ifcopenshell.api.run("material.assign_material", ifc, product=element_type, material=material)
+        ifcopenshell.api.run("material.assign_material", ifc, products=[element_type], material=material)
         material.Name = "Bar"
         material = ifcopenshell.api.run("material.add_material", ifc)
-        ifcopenshell.api.run("material.assign_material", ifc, product=element, material=material)
+        ifcopenshell.api.run("material.assign_material", ifc, products=[element], material=material)
         material.Name = "Foo"
         facet = Material(value="Foo")
         run("Occurrences can override materials from their types", facet=facet, inst=element, expected=True)