You can now associate annotations with objects for smart annotations in IFC. See #1153.

src/ifcopenshell-python/ifcopenshell/api/drawing/assign_product.py

@@ -0,0 +1,43 @@
+import ifcopenshell
+import ifcopenshell.api
+
+
+class Usecase:
+    def __init__(self, file, **settings):
+        self.file = file
+        self.settings = {
+            "relating_product": None,
+            "related_object": None,
+        }
+        for key, value in settings.items():
+            self.settings[key] = value
+
+    def execute(self):
+        if self.settings["related_object"].HasAssignments:
+            for assignment in self.settings["related_object"].HasAssignments:
+                if (
+                    assignment.is_a("IfcRelAssignsToProduct")
+                    and assignment.RelatingProduct == self.settings["relating_product"]
+                ):
+                    return
+
+        referenced_by = None
+        if self.settings["relating_product"].ReferencedBy:
+            referenced_by = self.settings["relating_product"].ReferencedBy[0]
+
+        if referenced_by:
+            related_objects = list(referenced_by.RelatedObjects)
+            related_objects.append(self.settings["related_object"])
+            referenced_by.RelatedObjects = related_objects
+            ifcopenshell.api.run("owner.update_owner_history", self.file, **{"element": referenced_by})
+        else:
+            referenced_by = self.file.create_entity(
+                "IfcRelAssignsToProduct",
+                **{
+                    "GlobalId": ifcopenshell.guid.new(),
+                    "OwnerHistory": ifcopenshell.api.run("owner.create_owner_history", self.file),
+                    "RelatedObjects": [self.settings["related_object"]],
+                    "RelatingProduct": self.settings["relating_product"],
+                }
+            )
+        return referenced_by

src/ifcopenshell-python/ifcopenshell/api/drawing/unassign_product.py

@@ -0,0 +1,25 @@
+import ifcopenshell
+import ifcopenshell.api
+
+
+class Usecase:
+    def __init__(self, file, **settings):
+        self.file = file
+        self.settings = {
+            "relating_product": None,
+            "related_object": None,
+        }
+        for key, value in settings.items():
+            self.settings[key] = value
+
+    def execute(self):
+        for rel in self.settings["related_object"].HasAssignments or []:
+            if not rel.is_a("IfcRelAssignsToProduct") or rel.RelatingProduct != self.settings["relating_product"]:
+                continue
+            if len(rel.RelatedObjects) == 1:
+                return self.file.remove(rel)
+            related_objects = list(rel.RelatedObjects)
+            related_objects.remove(self.settings["related_object"])
+            rel.RelatedObjects = related_objects
+            ifcopenshell.api.run("owner.update_owner_history", self.file, **{"element": rel})
+            return rel

src/ifcopenshell-python/test/api/drawing/test_assign_product.py

@@ -0,0 +1,20 @@
+import test.bootstrap
+import ifcopenshell.api
+
+
+class TestAssignProduct(test.bootstrap.IFC4):
+    def test_assigning_a_product(self):
+        wall = self.file.createIfcWall()
+        label = self.file.createIfcAnnotation()
+        label2 = self.file.createIfcAnnotation()
+        ifcopenshell.api.run("drawing.assign_product", self.file, relating_product=wall, related_object=label)
+        assert wall.ReferencedBy[0].RelatedObjects == (label,)
+        ifcopenshell.api.run("drawing.assign_product", self.file, relating_product=wall, related_object=label2)
+        assert wall.ReferencedBy[0].RelatedObjects == (label, label2)
+
+    def test_not_assigning_twice(self):
+        wall = self.file.createIfcWall()
+        label = self.file.createIfcAnnotation()
+        ifcopenshell.api.run("drawing.assign_product", self.file, relating_product=wall, related_object=label)
+        ifcopenshell.api.run("drawing.assign_product", self.file, relating_product=wall, related_object=label)
+        assert wall.ReferencedBy[0].RelatedObjects == (label,)

src/ifcopenshell-python/test/api/drawing/test_unassign_product.py

@@ -0,0 +1,11 @@
+import test.bootstrap
+import ifcopenshell.api
+
+
+class TestUnassignProduct(test.bootstrap.IFC4):
+    def test_unassigning_a_product(self):
+        wall = self.file.createIfcWall()
+        label = self.file.createIfcAnnotation()
+        ifcopenshell.api.run("drawing.assign_product", self.file, relating_product=wall, related_object=label)
+        ifcopenshell.api.run("drawing.unassign_product", self.file, relating_product=wall, related_object=label)
+        assert len(self.file.by_type("IfcRelAssignsToProduct")) == 0