Types: Accept marshalling datetime.date values on DateTime fields

The test suite of `meltano-tap-cratedb`, derived from the corresponding
PostgreSQL adapter, will supply `dt.date` objects. Without this patch,
those will otherwise fail on this routine.

CHANGES.md

@@ -4,6 +4,7 @@
 ## Unreleased
 - Added/reactivated documentation as `sqlalchemy-cratedb`
 - Unlocked supporting timezone-aware `DateTime` fields
+- Added support for marshalling Python `datetime.date` values on `sa.DateTime` fields
 
 ## 2024/06/13 0.37.0
 - Added support for CrateDB's [FLOAT_VECTOR] data type and its accompanying

src/sqlalchemy_cratedb/dialect.py

@@ -114,10 +114,10 @@ class DateTime(sqltypes.DateTime):
 
     def bind_processor(self, dialect):
         def process(value):
-            if value is not None:
-                assert isinstance(value, datetime)
+            if isinstance(value, (datetime, date)):
                 return value.strftime('%Y-%m-%dT%H:%M:%S.%fZ')
-            return value
+            else:
+                return value
         return process
 
     def result_processor(self, dialect, coltype):

tests/datetime_test.py

@@ -167,3 +167,31 @@ def test_datetime_tz(session):
     assert result["datetime"].tzname() is None
     assert result["datetime"].timetz() == dt.time(19, 19, 30, 123000)
     assert result["datetime"].tzinfo is None
+
+
+@pytest.mark.skipif(SA_VERSION < SA_1_4, reason="Test case not supported on SQLAlchemy 1.3")
+def test_datetime_date(session):
+    """
+    Validate assigning a `date` object to a `datetime` column works.
+
+    It is needed by meltano-tap-cratedb.
+
+    The test suite of `meltano-tap-cratedb`, derived from the corresponding
+    PostgreSQL adapter, will supply `dt.date` objects. Without this improvement,
+    those will otherwise fail.
+    """
+
+    # Insert record.
+    foo_item = FooBar(
+        name="foo",
+        datetime=dt.date(2009, 5, 13),
+    )
+    session.add(foo_item)
+    session.commit()
+    session.execute(sa.text("REFRESH TABLE foobar"))
+
+    # Query record.
+    result = session.execute(sa.select(FooBar.name, FooBar.date, FooBar.datetime)).mappings().first()
+
+    # Compare outcome.
+    assert result["datetime"] == dt.datetime(2009, 5, 13, 0, 0, 0)