Fix rejecting null on optional fields (#761)

aiohttp_admin/backends/abc.py

@@ -3,6 +3,7 @@
 import sys
 import warnings
 from abc import ABC, abstractmethod
+from collections.abc import Sequence
 from datetime import date, datetime, time
 from enum import Enum
 from functools import cached_property, partial
@@ -16,6 +17,11 @@
 from ..security import check, permissions_as_dict
 from ..types import ComponentState, InputState
 
+if sys.version_info >= (3, 10):
+    from typing import TypeAlias
+else:
+    from typing_extensions import TypeAlias
+
 if sys.version_info >= (3, 12):
     from typing import TypedDict
 else:
@@ -110,7 +116,7 @@ def __init__(self) -> None:
         if "id" in self.fields and self.primary_key != "id":
             warnings.warn("A non-PK 'id' column is likely to break the admin.", stacklevel=2)
 
-        d = {k: INPUT_TYPES.get(v["type"], str) for k, v in self.inputs.items()}
+        d = {k: self._get_input_type(v) for k, v in self.inputs.items()}
         # For runtime type checking only.
         self._record_type = TypedDict("RecordType", d, total=False)  # type: ignore[misc]
 
@@ -313,6 +319,12 @@ async def _delete_many(self, request: web.Request) -> web.Response:
             raise web.HTTPNotFound()
         return json_response({"data": ids})
 
+    def _get_input_type(self, inp: InputState) -> TypeAlias:
+        t = INPUT_TYPES.get(inp["type"], str)
+        validators = inp.get("props", {}).get("validate", ())
+        assert isinstance(validators, Sequence)  # noqa: S101
+        return t if any(v["name"] == "required" for v in validators) else Optional[t]
+
     @cached_property
     def routes(self) -> tuple[web.RouteDef, ...]:
         """Routes to act on this resource.

tests/test_backends_abc.py

@@ -0,0 +1,16 @@
+import json
+from collections.abc import Awaitable, Callable
+
+from aiohttp.test_utils import TestClient
+
+_Login = Callable[[TestClient], Awaitable[dict[str, str]]]
+
+
+async def test_create_with_null(admin_client: TestClient, login: _Login) -> None:
+    h = await login(admin_client)
+    assert admin_client.app
+    url = admin_client.app["admin"].router["dummy2_create"].url_for()
+    p = {"data": json.dumps({"msg": None})}
+    async with admin_client.post(url, params=p, headers=h) as resp:
+        assert resp.status == 200, await resp.text()
+        assert await resp.json() == {"data": {"id": 4, "msg": None}}