Regression: TypeError with UUID primary keys in 0.22.0: issubclass() arg 1 must be a class

[S3wnkin]

Checklist

• The bug is reproducible against the latest release or master.
• There are no similar issues or pull requests to fix it yet.

Describe the bug

sqladmin 0.22.0 throws TypeError: issubclass() arg 1 must be a class when accessing the detail view for models with UUID primary keys using Annotated types. This is a regression introduced in version 0.22.0 - version 0.21.0 works correctly.

Steps to reproduce the bug

1. Create a model with UUID primary key using Annotated:

from uuid import UUID
from typing import Annotated
from sqlalchemy.orm import DeclarativeBase, Mapped, mapped_column

class Base(DeclarativeBase):
    pass

class User(Base):
    __tablename__ = "users"
    id: Mapped[UUID] = mapped_column(primary_key=True)

2. Set up sqladmin with this model
3. Navigate to user list view (works fine)
4. Click to view user details: /admin/user/details/{uuid}
5. Error occurs

Expected behavior

Detail view should load successfully, displaying the user record details as it did in sqladmin 0.21.0.

Actual behavior

Application crashes with TypeError: issubclass() arg 1 must be a class when trying to access any detail view for models with UUID primary keys.

Debugging material

Full Traceback

``` File ".../sqladmin/models.py", line 904, in get_object_for_details stmt = self.details_query(request) File ".../sqladmin/models.py", line 1162, in details_query return self.form_edit_query(request) File ".../sqladmin/models.py", line 1178, in form_edit_query stmt = self._stmt_by_identifier(request.path_params["pk"]) File ".../sqladmin/models.py", line 918, in _stmt_by_identifier values = object_identifier_values(identifier, self.model) File ".../sqladmin/helpers.py", line 230, in object_identifier_values if issubclass(type_, (date, datetime, time)): ~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ TypeError: issubclass() arg 1 must be a class ```

Root Cause:
PR #958 added a date/time type check in helpers.py:230 but doesn't handle Annotated types properly. When type_ is a typing._AnnotatedAlias (not an actual class), issubclass() fails.

Proposed Fix:

# sqladmin/helpers.py line ~230
if isinstance(type_, type) and issubclass(type_, (date, datetime, time)):
    # existing logic

Environment

• sqladmin: 0.22.0
• Python: 3.13
• SQLAlchemy: 2.0.38
• pydantic: 2.10.6

Additional context

This regression was introduced in PR #958 which aimed to fix date/time primary key handling. The fix works for date/time types but breaks UUID primary keys when using type annotations.

Workaround: Downgrade to sqladmin 0.21.0

[mmzeynalli]

I believe, there is something missing in your report. I added this test, and it works:

from typing import Any, Generator
from uuid import UUID

import pytest
from sqlalchemy import ForeignKey
from sqlalchemy.orm import (
    Mapped,
    declarative_base,
    mapped_column,
    relationship,
    sessionmaker,
)
from starlette.applications import Starlette
from starlette.testclient import TestClient

from sqladmin import Admin, ModelView
from tests.common import sync_engine as engine

Base = declarative_base()  # type: Any
session_maker = sessionmaker(bind=engine)

app = Starlette()
admin = Admin(app=app, engine=engine)


class User(Base):
    __tablename__ = "users"

    uuid: Mapped[UUID] = mapped_column(primary_key=True)
    name: Mapped[str]
    posts: Mapped[list["Post"]] = relationship("Post", back_populates="user")

    def __str__(self) -> str:
        return f"User {self.uuid}"


class Post(Base):
    __tablename__ = "posts"

    id: Mapped[int] = mapped_column(primary_key=True)
    user_id: Mapped[UUID] = mapped_column(ForeignKey("users.uuid"))
    user: Mapped[User] = relationship("User", back_populates="posts")
    title: Mapped[str]


@pytest.fixture
def prepare_database() -> Generator[None, None, None]:
    Base.metadata.create_all(engine)
    yield
    Base.metadata.drop_all(engine)


@pytest.fixture
def client(prepare_database: Any) -> Generator[TestClient, None, None]:
    with TestClient(app=app, base_url="http://testserver") as c:
        yield c


class UserAdmin(ModelView, model=User):
    column_list = [User.uuid, User.name]


class PostAdmin(ModelView, model=Post):
    column_list = [Post.id, Post.title, Post.user]


admin.add_view(UserAdmin)
admin.add_view(PostAdmin)


def base_content():
    with session_maker() as session:
        user = User(uuid=UUID("00000000-0000-0000-0000-000000000001"), name="John")
        session.add(user)

        post1 = Post(id=1, title="Post 1", user_id=user.uuid)
        post2 = Post(id=2, title="Post 2", user_id=user.uuid)
        session.add_all([post1, post2])
        session.commit()


def test_uuid_pk_view(client: TestClient) -> None:
    base_content()
    response = client.get("/admin/user/details/00000000-0000-0000-0000-000000000001")
    assert response.status_code == 200

The test passes, and I get output of print(type_, type(type_)) at the point that you have exception:

<class 'uuid.UUID'> <class 'type'>

[S3wnkin]

I've identified the root cause and have a fix ready. The issue specifically occurs when using FastAPI-Users' GUID TypeDecorator.

Technical Details

FastAPI-Users' GUID type is a TypeDecorator that defines an inner UUIDChar class:

class GUID(TypeDecorator):
    class UUIDChar(CHAR):
        python_type = UUID4  # This is pydantic's UUID4, not a class
    
    impl = UUIDChar

When get_column_python_type() is called on this column, it returns pydantic's UUID4 (a typing._AnnotatedAlias), not the standard uuid.UUID class. This causes the issubclass() check to fail.

Solution

I've fixed this by adding an inspect.isclass() guard before the issubclass() calls:

if inspect.isclass(type_) and issubclass(type_, (date, datetime, time)):
    value = type_.fromisoformat(part)
elif inspect.isclass(type_) and issubclass(type_, bool):
    value = False if part == "False" else type_(part)

This properly handles TypeDecorators, Annotated types, and any other non-class type annotations.

Submitting a PR now.

[SnoozeFreddo]

+1