fix: sqlalchemy dto for models non Column fields (#75)

advanced_alchemy/extensions/litestar/dto.py

@@ -26,6 +26,7 @@
     RelationshipDirection,
     RelationshipProperty,
 )
+from sqlalchemy.sql.expression import ColumnClause, Label
 
 from advanced_alchemy.exceptions import ImproperConfigurationError
 
@@ -38,7 +39,7 @@
 
 T = TypeVar("T", bound="DeclarativeBase | Collection[DeclarativeBase]")
 
-ElementType: TypeAlias = "Column | RelationshipProperty | CompositeProperty"
+ElementType: TypeAlias = "Column | RelationshipProperty | CompositeProperty | ColumnClause | Label"
 SQLA_NS = {**vars(orm), **vars(sql)}
 
 
@@ -102,8 +103,8 @@ def _(
 
         elem: ElementType
         if isinstance(orm_descriptor.property, ColumnProperty):
-            if not isinstance(orm_descriptor.property.expression, Column):
-                msg = f"Expected 'Column', got: '{orm_descriptor.property.expression}'"
+            if not isinstance(orm_descriptor.property.expression, (Column, ColumnClause, Label)):
+                msg = f"Expected 'Column', got: '{orm_descriptor.property.expression}, {type(orm_descriptor.property.expression)}'"
                 raise NotImplementedError(msg)
             elem = orm_descriptor.property.expression
         elif isinstance(orm_descriptor.property, (RelationshipProperty, CompositeProperty)):
@@ -123,6 +124,7 @@ def _(
         except KeyError:
             field_definition = parse_type_from_element(elem)
 
+        dto_field = elem.info.get(DTO_FIELD_META_KEY, DTOField()) if hasattr(elem, "info") else DTOField()
         return [
             DTOFieldDefinition.from_field_definition(
                 field_definition=replace(
@@ -131,7 +133,7 @@ def _(
                     default=default,
                 ),
                 default_factory=default_factory,
-                dto_field=elem.info.get(DTO_FIELD_META_KEY, DTOField()),
+                dto_field=dto_field,
                 model_name=model_name,
             ),
         ]
@@ -348,7 +350,7 @@ def parse_type_from_element(elem: ElementType) -> FieldDefinition:
     if isinstance(elem, CompositeProperty):
         return FieldDefinition.from_annotation(elem.composite_class)
 
-    msg = f"Unable to parse type from element '{elem}'. Consider adding a type hint."  # type: ignore[unreachable]
+    msg = f"Unable to parse type from element '{elem}'. Consider adding a type hint."
     raise ImproperConfigurationError(
         msg,
     )

tests/unit/test_extensions/test_litestar/test_dto_integration.py

@@ -2,7 +2,7 @@
 
 from dataclasses import dataclass
 from types import ModuleType
-from typing import Any, Callable, Dict, List, Tuple
+from typing import Any, Callable, Dict, List, Optional, Tuple
 
 import pytest
 from litestar import get, post
@@ -12,7 +12,7 @@
 from litestar.dto.field import DTO_FIELD_META_KEY
 from litestar.dto.types import RenameStrategy
 from litestar.testing import create_test_client
-from sqlalchemy import Column, ForeignKey, Integer, String, Table
+from sqlalchemy import Column, ForeignKey, Integer, String, Table, func, select
 from sqlalchemy.ext.hybrid import hybrid_property
 from sqlalchemy.orm import (
     DeclarativeBase,
@@ -56,6 +56,9 @@ class Book(Base):
     bar: Mapped[str] = mapped_column(default="Hello")  # pyright: ignore
     SPAM: Mapped[str] = mapped_column(default="Bye")  # pyright: ignore
     spam_bar: Mapped[str] = mapped_column(default="Goodbye")  # pyright: ignore
+    number_of_reviews: Mapped[Optional[int]] = column_property(  # noqa: UP007
+        select(func.count(BookReview.id)).where(BookReview.book_id == id).scalar_subquery(),
+    )
 
 
 @dataclass
@@ -70,6 +73,7 @@ class BookAuthorTestData:
     book_spam_bar: str = "GoodBye"
     book_review_id: str = "23432"
     book_review: str = "Excellent!"
+    number_of_reviews: int | None = None
 
 
 @pytest.fixture
@@ -94,6 +98,7 @@ def _generate(rename_strategy: RenameStrategy, test_data: BookAuthorTestData) ->
                     _rename_field(name="review", strategy=rename_strategy): test_data.book_review,
                 },
             ],
+            _rename_field(name="number_of_reviews", strategy=rename_strategy): test_data.number_of_reviews,
         }
         book = Book(
             id=test_data.book_id,
@@ -147,6 +152,35 @@ def get_handler() -> Book:
         assert response_callback.json() == json_data
 
 
+class ConcreteBase(Base):
+    pass
+
+
+func_result_query = select(func.count(1)).scalar_subquery()
+model_with_func_query = select(ConcreteBase, func_result_query.label("func_result")).subquery()
+
+
+class ModelWithFunc(Base):
+    __table__ = model_with_func_query
+    func_result: Mapped[Optional[int]] = column_property(model_with_func_query.c.func_result)  # noqa: UP007
+
+
+def test_model_using_func() -> None:
+    instance = ModelWithFunc(id="hi")
+    config = SQLAlchemyDTOConfig()
+    dto = SQLAlchemyDTO[Annotated[ModelWithFunc, config]]
+
+    @get(dto=dto, signature_namespace={"ModelWithFunc": ModelWithFunc})
+    def get_handler() -> ModelWithFunc:
+        return instance
+
+    with create_test_client(
+        route_handlers=[get_handler],
+    ) as client:
+        response_callback = client.get("/")
+        assert response_callback
+
+
 def test_dto_with_association_proxy(create_module: Callable[[str], ModuleType]) -> None:
     module = create_module(
         """