Skip to content

fix: resolve TypeAliasType before issubclass in pack_union (fixes #330) #336

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Open
gaoflow wants to merge 2 commits into
base: master
Choose a base branch
from
Open

fix: resolve TypeAliasType before issubclass in pack_union (fixes #330) #336

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
2 commits
Select commit Hold shift + click to select a range
c0c34ee
fix: resolve TypeAliasType before issubclass in pack_union (#330)
gaoflow Jun 18, 2026
64923fe
Cover PEP 695 alias union value packing
gaoflow Jun 20, 2026
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
11 changes: 9 additions & 2 deletions mashumaro/core/meta/types/pack.py
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -292,6 +292,12 @@ def pack_any(spec: ValueSpec) -> Expression | None:
return spec.expression


def _resolve_type_alias_type(t: type) -> type:
while is_type_alias_type(t):
t = t.__value__ # type: ignore[attr-defined]
return t


def pack_union(
spec: ValueSpec, args: tuple[type, ...], prefix: str = "union"
) -> Expression:
Expand Down Expand Up @@ -330,7 +336,7 @@ def pack_union(
)
if packer not in packers:
if packer == "value" and not issubclass(
get_type_origin(type_arg), Collection
get_type_origin(_resolve_type_alias_type(type_arg)), Collection
):
packers.insert(0, packer)
else:
Expand All @@ -344,6 +350,7 @@ def pack_union(
for packer in packers:
packer_arg_type_names = []
for packer_arg_type in packer_arg_types[packer]:
packer_arg_type = _resolve_type_alias_type(packer_arg_type)
if is_generic(packer_arg_type):
packer_arg_type = get_type_origin(packer_arg_type)
packer_arg_type_name = clean_id(type_name(packer_arg_type))
Expand All @@ -359,7 +366,7 @@ def pack_union(
else:
packer_arg_type_check = f"is {packer_arg_type_names[0]}"
if packer == "value" and not issubclass(
packer_arg_type, Collection
_resolve_type_alias_type(packer_arg_type), Collection
):
with lines.indent(
f"if value.__class__ {packer_arg_type_check}:"
Expand Down
11 changes: 11 additions & 0 deletions tests/test_pep_695.py
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -16,6 +16,8 @@
GenericPassthroughSerializable,
)

type ScalarAlias = int


def test_type_alias_type_with_dataclass_dict_mixin():
type MyDate = date
Expand All @@ -39,6 +41,15 @@ def test_type_alias_type_with_codecs():
assert encoder.encode(obj) == "2024-04-15"


def test_type_alias_type_with_union_value_packer():
@dataclass
class MyClass(DataClassDictMixin):
x: ScalarAlias | list[int]

assert MyClass(1).to_dict() == {"x": 1}
assert MyClass([1, 2]).to_dict() == {"x": [1, 2]}


@pytest.mark.parametrize("deferred_ann", [False, True])
def test_pep695_generic_serialization_strategy(deferred_ann):
if deferred_ann:
Expand Down
Loading