From 6bf9b8b0c980c3ba658a907c38ce072630614100 Mon Sep 17 00:00:00 2001
From: Dion Moult <dion@thinkmoult.com>
Date: Fri, 9 May 2025 15:24:17 +1000
Subject: [PATCH] Fix bug where appending assets could accidentally create
 duplicate contexts

---
 .../ifcopenshell/api/project/append_asset.py  | 20 +++++++++++-------
 .../test/api/project/test_append_asset.py     | 21 +++++++++++++++++++
 2 files changed, 34 insertions(+), 7 deletions(-)

diff --git a/src/ifcopenshell-python/ifcopenshell/api/project/append_asset.py b/src/ifcopenshell-python/ifcopenshell/api/project/append_asset.py
index d92c50135d..00c11dc72c 100644
--- a/src/ifcopenshell-python/ifcopenshell/api/project/append_asset.py
+++ b/src/ifcopenshell-python/ifcopenshell/api/project/append_asset.py
@@ -506,7 +506,9 @@ class Usecase:
     def reuse_existing_contexts(self) -> None:
         added_contexts = set([e for e in self.added_elements.values() if e.is_a("IfcGeometricRepresentationContext")])
         added_contexts -= set(self.existing_contexts)
-        for added_context in added_contexts:
+        sorted_added_contexts = [c for c in added_contexts if c.is_a() == "IfcGeometricRepresentationContext"]
+        sorted_added_contexts.extend([c for c in added_contexts if c.is_a() == "IfcGeometricRepresentationSubContext"])
+        for added_context in sorted_added_contexts:
             equivalent_existing_context = self.get_equivalent_existing_context(added_context)
             if not equivalent_existing_context:
                 equivalent_existing_context = self.create_equivalent_context(added_context)
@@ -541,18 +543,22 @@ class Usecase:
             parent = self.get_equivalent_existing_context(added_context.ParentContext)
             if not parent:
                 parent = self.create_equivalent_context(added_context.ParentContext)
-            return ifcopenshell.api.context.add_context(
+                self.existing_contexts.append(parent)
+            context = ifcopenshell.api.context.add_context(
                 self.file,
                 parent=parent,
                 context_type=added_context.ContextType,
                 context_identifier=added_context.ContextIdentifier,
                 target_view=added_context.TargetView,
             )
-        return ifcopenshell.api.context.add_context(
-            self.file,
-            context_type=added_context.ContextType,
-            context_identifier=added_context.ContextIdentifier,
-        )
+        else:
+            context = ifcopenshell.api.context.add_context(
+                self.file,
+                context_type=added_context.ContextType,
+                context_identifier=added_context.ContextIdentifier,
+            )
+        self.existing_contexts.append(context)
+        return context
 
     def file_add(
         self, element: ifcopenshell.entity_instance, conversion_factor: Optional[float] = None
diff --git a/src/ifcopenshell-python/test/api/project/test_append_asset.py b/src/ifcopenshell-python/test/api/project/test_append_asset.py
index 3a937cc4c3..3028269931 100644
--- a/src/ifcopenshell-python/test/api/project/test_append_asset.py
+++ b/src/ifcopenshell-python/test/api/project/test_append_asset.py
@@ -81,6 +81,27 @@ class TestAppendAssetIFC2X3(test.bootstrap.IFC2X3):
         # make sure it's still valid
         assert context.WorldCoordinateSystem
 
+    def test_add_new_contexts_if_necessary(self):
+        library = ifcopenshell.api.project.create_file(version=self.file.schema)
+        ifcopenshell.api.root.create_entity(library, ifc_class="IfcProject")
+        lib_context = ifcopenshell.api.context.add_context(library, context_type="Model")
+        lib_subcontext = ifcopenshell.api.context.add_context(library, context_type="Model", context_identifier="Body", target_view="MODEL_VIEW", parent=lib_context)
+
+        # It has no contexts right now
+        ifcopenshell.api.root.create_entity(self.file, ifc_class="IfcProject")
+
+        material = ifcopenshell.api.material.add_material(library, name="Material")
+        style = ifcopenshell.api.style.add_style(library)
+        ifcopenshell.api.style.assign_material_style(library, material=material, style=style, context=lib_subcontext)
+
+        ifcopenshell.api.project.append_asset(self.file, library=library, element=material)
+        assert len(self.file.by_type("IfcProject")) == 1
+        assert len(self.file.by_type("IfcGeometricRepresentationContext", include_subtypes=False)) == 1
+        assert len(self.file.by_type("IfcGeometricRepresentationSubContext", include_subtypes=False)) == 1
+        context = self.file.by_type("IfcMaterial")[0].HasRepresentation[0].Representations[0].ContextOfItems
+        # make sure it's still valid
+        assert context.WorldCoordinateSystem
+
     def test_append_a_single_type_product_even_though_an_inverse_material_relationship_is_shared(self):
         library = ifcopenshell.api.project.create_file(version=self.file.schema)
         element = ifcopenshell.api.root.create_entity(library, ifc_class="IfcWallType")