You can now add IFC subdocuments or supersede documents

src/ifcopenshell-python/ifcopenshell/api/document/add_information.py

@@ -29,12 +29,12 @@ class Usecase:
     def execute(self):
         id_attribute = "DocumentId" if self.file.schema == "IFC2X3" else "Identification"
         information = self.file.create_entity(
-            "IfcDocumentInformation", **{id_attribute: ifcopenshell.guid.new(), "Name": "Unnamed"}
+            "IfcDocumentInformation", **{id_attribute: "X", "Name": "Unnamed"}
         )
         parent = self.settings["parent"]
         if not parent and self.file.by_type("IfcProject"):
             parent = self.file.by_type("IfcProject")[0]
-        if parent.is_a("IfcProject") or prarent.is_a("IfcContext"):
+        if parent.is_a("IfcProject") or parent.is_a("IfcContext"):
             self.file.create_entity(
                 "IfcRelAssociatesDocument",
                 GlobalId=ifcopenshell.guid.new(),
@@ -42,4 +42,16 @@ class Usecase:
                 RelatingDocument=information,
                 RelatedObjects=[parent],
             )
+        elif parent.is_a("IfcDocumentInformation"):
+            if parent.IsPointer:
+                rel = parent.IsPointer[0]
+                documents = set(rel.RelatedDocuments)
+                documents.add(information)
+                rel.RelatedDocuments = list(documents)
+            else:
+                self.file.create_entity(
+                    "IfcDocumentInformationRelationship",
+                    RelatingDocument=parent,
+                    RelatedDocuments=[information]
+                )
         return information

src/ifcopenshell-python/test/api/document/test_add_information.py

@@ -22,7 +22,7 @@ import ifcopenshell.api
 
 class TestAddInformation(test.bootstrap.IFC4):
     def test_adding_information(self):
-        self.file.createIfcProject()
+        project = self.file.createIfcProject()
         element = ifcopenshell.api.run("document.add_information", self.file, parent=None)
         assert element.is_a("IfcDocumentInformation")
         assert len(self.file.by_type("IfcDocumentInformation")) == 1
@@ -33,3 +33,15 @@ class TestAddInformation(test.bootstrap.IFC4):
         rel = element.DocumentInfoForObjects[0]
         assert rel.is_a("IfcRelAssociatesDocument")
         assert rel.RelatedObjects[0] == project
+
+    def test_adding_a_subdocument(self):
+        project = self.file.createIfcProject()
+        parent = ifcopenshell.api.run("document.add_information", self.file, parent=None)
+        element = ifcopenshell.api.run("document.add_information", self.file, parent=parent)
+        assert element.is_a("IfcDocumentInformation")
+        assert len(self.file.by_type("IfcDocumentInformation")) == 2
+        assert element.IsPointedTo[0].RelatingDocument == parent
+        assert parent.IsPointer[0].RelatedDocuments[0] == element
+        element2 = ifcopenshell.api.run("document.add_information", self.file, parent=parent)
+        assert element in parent.IsPointer[0].RelatedDocuments
+        assert element2 in parent.IsPointer[0].RelatedDocuments