Issue #330: Enable deep copy

- properly handle collection features that have None value

Author: reckart

cassis/cas.py

@@ -1038,13 +1038,21 @@ def _build_fs_list(referenced_list: List[Optional[int]]) -> FeatureStructure:
                 if ts.is_primitive(feature.rangeType):
                     fs_copy[feature.name] = fs.get(feature.name)
                 elif ts.is_primitive_collection(feature.rangeType):
+                    val = fs.get(feature.name)
+                    if val is None:
+                        continue
+
                     fs_copy[feature.name] = ts.get_type(feature.rangeType.name)()
-                    fs_copy[feature.name].elements = fs.get(feature.name).elements
+                    fs_copy[feature.name].elements = val.elements
                 elif ts.is_array(feature.rangeType):
+                    val = fs[feature.name]
+                    if val is None:
+                        continue
+
                     fs_copy[feature.name] = ts.get_type(TYPE_NAME_FS_ARRAY)()
                     # collect referenced xmiIDs for mapping later and preserve None placeholders
                     referenced_list = []
-                    for item in fs[feature.name].elements:
+                    for item in val.elements:
                         if item is None:
                             referenced_list.append(None)
                         elif hasattr(item, "xmiID") and item.xmiID is not None:

tests/test_cas.py

@@ -1018,7 +1018,7 @@ def test_crop_sofa_string_transitive_references_remain(small_typesystem_xml):
     cas = Cas(typesystem=typesystem)
 
     # Create parent and child types and a feature on parent referencing child
-    typesystem.create_type("test.Child")
+    Child = typesystem.create_type("test.Child")
     Parent = typesystem.create_type("test.Parent")
     typesystem.create_feature("test.Parent", "child", "test.Child")
 
@@ -1179,6 +1179,50 @@ def test_deep_copy_none_non_primitive_feature():
     assert getattr(copied_parent, "child") is None
 
 
+def test_deep_copy_none_fsarray_feature():
+    """Ensure an FSArray feature set to None is preserved in the copy."""
+    typesystem = TypeSystem()
+    Foo = typesystem.create_type("test.Foo")
+    typesystem.create_feature(
+        Foo,
+        "arr",
+        rangeType=typesystem.get_type("uima.cas.FSArray"),
+        elementType=typesystem.get_type(TYPE_NAME_TOP),
+        multipleReferencesAllowed=True,
+    )
+
+    cas = Cas(typesystem=typesystem)
+    foo = Foo()
+    foo.arr = None
+    cas.add(foo)
+
+    copy = cas.deep_copy(copy_typesystem=False)
+    copied_foo = list(copy.select("test.Foo"))[0]
+    assert getattr(copied_foo, "arr") is None
+
+
+def test_deep_copy_none_primitive_collection_feature():
+    """Ensure a primitive collection feature set to None is preserved in the copy."""
+    typesystem = TypeSystem()
+    Foo = typesystem.create_type("test.Foo")
+    typesystem.create_feature(
+        Foo,
+        "ints",
+        rangeType=typesystem.get_type(TYPE_NAME_INTEGER_ARRAY),
+        elementType=typesystem.get_type(TYPE_NAME_INTEGER),
+        multipleReferencesAllowed=True,
+    )
+
+    cas = Cas(typesystem=typesystem)
+    foo = Foo()
+    foo.ints = None
+    cas.add(foo)
+
+    copy = cas.deep_copy(copy_typesystem=False)
+    copied_foo = list(copy.select("test.Foo"))[0]
+    assert getattr(copied_foo, "ints") is None
+
+
 def test_deep_copy_empty_array():
     """Ensure empty FSArray is preserved as empty in the copy."""
     typesystem = TypeSystem()