Deserializer: add Nullable fields

pkgs/clan-cli/clan_cli/api/serde.py

@@ -96,7 +96,7 @@ def is_union_type(type_hint: type | UnionType) -> bool:
 def is_type_in_union(union_type: type | UnionType, target_type: type) -> bool:
     if get_origin(union_type) is UnionType:
         return any(issubclass(arg, target_type) for arg in get_args(union_type))
-    return False
+    return union_type == target_type
 
 
 def unwrap_none_type(type_hint: type | UnionType) -> type:
@@ -121,6 +121,8 @@ def construct_field(t: type, field_value: JsonValue, loc: list[str] = []) -> Any
     """
     Construct a field value from a type hint and a field value.
     """
+    if t is None and field_value:
+        raise ClanError(f"Expected None but got: {field_value}", location=f"{loc}")
     # If the field is another dataclass
     # Field_value must be a dictionary
     if is_dataclass(t) and isinstance(field_value, dict):
@@ -195,8 +197,6 @@ def from_dict(t: type[T], data: dict[str, Any], path: list[str] = []) -> T:
         field_type: type[Any] = unwrap_none_type(field.type)  # type: ignore
         data_field_name = field.metadata.get("alias", field.name)
 
-        # Check if the field is required
-        # breakpoint()
         if (
             field.default is dataclasses.MISSING
             and field.default_factory is dataclasses.MISSING
@@ -207,7 +207,13 @@ def from_dict(t: type[T], data: dict[str, Any], path: list[str] = []) -> T:
         # if present in the data
         if data_field_name in data:
             field_value = data.get(data_field_name)
-            field_values[field.name] = construct_field(field_type, field_value)
+
+            if field_value is None and (
+                field.type is None or is_type_in_union(field.type, type(None))
+            ):
+                field_values[field.name] = None
+            else:
+                field_values[field.name] = construct_field(field_type, field_value)
 
     # Check that all required field are present.
     for field_name in required:

pkgs/clan-cli/tests/test_deserializers.py

@@ -83,6 +83,29 @@ def test_simple_field_missing() -> None:
         from_dict(Person, person_dict)
 
 
+def test_nullable() -> None:
+    @dataclass
+    class Person:
+        name: None
+
+    person_dict = {
+        "name": None,
+    }
+
+    from_dict(Person, person_dict)
+
+
+def test_nullable_non_exist() -> None:
+    @dataclass
+    class Person:
+        name: None
+
+    person_dict = {}
+
+    with pytest.raises(ClanError):
+        from_dict(Person, person_dict)
+
+
 def test_deserialize_extensive_inventory() -> None:
     # TODO: Make this an abstract test, so it doesn't break the test if the inventory changes
     data = {