feat: support Annotated[AsyncSession, Depends(...)] in PathDependency and BodyDependency (#146)

docs/module/dependencies.md

@@ -13,8 +13,13 @@ The `dependencies` module provides two factory functions that create FastAPI dep
 ```python
 from fastapi_toolsets.dependencies import PathDependency
 
+# Plain callable
 UserDep = PathDependency(model=User, field=User.id, session_dep=get_db)
 
+# Annotated
+SessionDep = Annotated[AsyncSession, Depends(get_db)]
+UserDep = PathDependency(model=User, field=User.id, session_dep=SessionDep)
+
 @router.get("/users/{user_id}")
 async def get_user(user: User = UserDep):
     return user
@@ -37,8 +42,14 @@ async def get_user(user: User = UserDep):
 ```python
 from fastapi_toolsets.dependencies import BodyDependency
 
+# Plain callable
 RoleDep = BodyDependency(model=Role, field=Role.id, session_dep=get_db, body_field="role_id")
 
+# Annotated
+SessionDep = Annotated[AsyncSession, Depends(get_db)]
+RoleDep = BodyDependency(model=Role, field=Role.id, session_dep=SessionDep, body_field="role_id")
+
+
 @router.post("/users")
 async def create_user(body: UserCreateSchema, role: Role = RoleDep):
     user = User(username=body.username, role=role)

src/fastapi_toolsets/dependencies.py

@@ -1,10 +1,12 @@
 """Dependency factories for FastAPI routes."""
 
 import inspect
+import typing
 from collections.abc import Callable
 from typing import Any, cast
 
 from fastapi import Depends
+from fastapi.params import Depends as DependsClass
 from sqlalchemy.ext.asyncio import AsyncSession
 
 from .crud import CrudFactory
@@ -13,6 +15,15 @@ from .types import ModelType, SessionDependency
 __all__ = ["BodyDependency", "PathDependency"]
 
 
+def _unwrap_session_dep(session_dep: SessionDependency) -> Callable[..., Any]:
+    """Extract the plain callable from ``Annotated[AsyncSession, Depends(fn)]`` if needed."""
+    if typing.get_origin(session_dep) is typing.Annotated:
+        for arg in typing.get_args(session_dep)[1:]:
+            if isinstance(arg, DependsClass):
+                return arg.dependency
+    return session_dep
+
+
 def PathDependency(
     model: type[ModelType],
     field: Any,
@@ -44,6 +55,7 @@ def PathDependency(
         ): ...
         ```
     """
+    session_callable = _unwrap_session_dep(session_dep)
     crud = CrudFactory(model)
     name = (
         param_name
@@ -53,7 +65,7 @@ def PathDependency(
     python_type = field.type.python_type
 
     async def dependency(
-        session: AsyncSession = Depends(session_dep), **kwargs: Any
+        session: AsyncSession = Depends(session_callable), **kwargs: Any
     ) -> ModelType:
         value = kwargs[name]
         return await crud.get(session, filters=[field == value])
@@ -70,7 +82,7 @@ def PathDependency(
                     "session",
                     inspect.Parameter.KEYWORD_ONLY,
                     annotation=AsyncSession,
-                    default=Depends(session_dep),
+                    default=Depends(session_callable),
                 ),
             ]
         ),
@@ -112,11 +124,12 @@ def BodyDependency(
         ): ...
         ```
     """
+    session_callable = _unwrap_session_dep(session_dep)
     crud = CrudFactory(model)
     python_type = field.type.python_type
 
     async def dependency(
-        session: AsyncSession = Depends(session_dep), **kwargs: Any
+        session: AsyncSession = Depends(session_callable), **kwargs: Any
     ) -> ModelType:
         value = kwargs[body_field]
         return await crud.get(session, filters=[field == value])
@@ -133,7 +146,7 @@ def BodyDependency(
                     "session",
                     inspect.Parameter.KEYWORD_ONLY,
                     annotation=AsyncSession,
-                    default=Depends(session_dep),
+                    default=Depends(session_callable),
                 ),
             ]
         ),

src/fastapi_toolsets/types.py

@@ -24,4 +24,4 @@ SearchFieldType = InstrumentedAttribute[Any] | tuple[InstrumentedAttribute[Any],
 FacetFieldType = SearchFieldType
 
 # Dependency type aliases
-SessionDependency = Callable[[], AsyncGenerator[AsyncSession, None]]
+SessionDependency = Callable[[], AsyncGenerator[AsyncSession, None]] | Any

tests/test_dependencies.py

@@ -3,13 +3,17 @@
 import inspect
 import uuid
 from collections.abc import AsyncGenerator
-from typing import Any, cast
+from typing import Annotated, Any, cast
 
 import pytest
 from fastapi.params import Depends
 from sqlalchemy.ext.asyncio import AsyncSession
 
-from fastapi_toolsets.dependencies import BodyDependency, PathDependency
+from fastapi_toolsets.dependencies import (
+    BodyDependency,
+    PathDependency,
+    _unwrap_session_dep,
+)
 
 from .conftest import Role, RoleCreate, RoleCrud, User
 
@@ -19,6 +23,24 @@ async def mock_get_db() -> AsyncGenerator[AsyncSession, None]:
     yield None
 
 
+MockSessionDep = Annotated[AsyncSession, Depends(mock_get_db)]
+
+
+class TestUnwrapSessionDep:
+    def test_plain_callable_returned_as_is(self):
+        """Plain callable is returned unchanged."""
+        assert _unwrap_session_dep(mock_get_db) is mock_get_db
+
+    def test_annotated_with_depends_unwrapped(self):
+        """Annotated form with Depends is unwrapped to the plain callable."""
+        assert _unwrap_session_dep(MockSessionDep) is mock_get_db
+
+    def test_annotated_without_depends_returned_as_is(self):
+        """Annotated form with no Depends falls back to returning session_dep as-is."""
+        annotated_no_dep = Annotated[AsyncSession, "not_a_depends"]
+        assert _unwrap_session_dep(annotated_no_dep) is annotated_no_dep
+
+
 class TestPathDependency:
     """Tests for PathDependency factory."""
 
@@ -95,6 +117,39 @@ class TestPathDependency:
         assert result.id == role.id
         assert result.name == "test_role"
 
+    def test_annotated_session_dep_returns_depends_instance(self):
+        """PathDependency accepts Annotated[AsyncSession, Depends(...)] form."""
+        dep = PathDependency(Role, Role.id, session_dep=MockSessionDep)
+        assert isinstance(dep, Depends)
+
+    def test_annotated_session_dep_signature(self):
+        """PathDependency with Annotated session_dep produces a valid signature."""
+        dep = cast(Any, PathDependency(Role, Role.id, session_dep=MockSessionDep))
+        sig = inspect.signature(dep.dependency)
+
+        assert "role_id" in sig.parameters
+        assert "session" in sig.parameters
+        assert isinstance(sig.parameters["session"].default, Depends)
+
+    def test_annotated_session_dep_unwraps_callable(self):
+        """PathDependency with Annotated form uses the underlying callable, not the Annotated type."""
+        dep = cast(Any, PathDependency(Role, Role.id, session_dep=MockSessionDep))
+        sig = inspect.signature(dep.dependency)
+
+        inner_dep = sig.parameters["session"].default
+        assert inner_dep.dependency is mock_get_db
+
+    @pytest.mark.anyio
+    async def test_annotated_session_dep_fetches_object(self, db_session):
+        """PathDependency with Annotated session_dep correctly fetches object from database."""
+        role = await RoleCrud.create(db_session, RoleCreate(name="annotated_role"))
+
+        dep = cast(Any, PathDependency(Role, Role.id, session_dep=MockSessionDep))
+        result = await dep.dependency(session=db_session, role_id=role.id)
+
+        assert result.id == role.id
+        assert result.name == "annotated_role"
+
 
 class TestBodyDependency:
     """Tests for BodyDependency factory."""
@@ -184,3 +239,39 @@ class TestBodyDependency:
 
         assert result.id == role.id
         assert result.name == "body_test_role"
+
+    def test_annotated_session_dep_returns_depends_instance(self):
+        """BodyDependency accepts Annotated[AsyncSession, Depends(...)] form."""
+        dep = BodyDependency(
+            Role, Role.id, session_dep=MockSessionDep, body_field="role_id"
+        )
+        assert isinstance(dep, Depends)
+
+    def test_annotated_session_dep_unwraps_callable(self):
+        """BodyDependency with Annotated form uses the underlying callable, not the Annotated type."""
+        dep = cast(
+            Any,
+            BodyDependency(
+                Role, Role.id, session_dep=MockSessionDep, body_field="role_id"
+            ),
+        )
+        sig = inspect.signature(dep.dependency)
+
+        inner_dep = sig.parameters["session"].default
+        assert inner_dep.dependency is mock_get_db
+
+    @pytest.mark.anyio
+    async def test_annotated_session_dep_fetches_object(self, db_session):
+        """BodyDependency with Annotated session_dep correctly fetches object from database."""
+        role = await RoleCrud.create(db_session, RoleCreate(name="body_annotated_role"))
+
+        dep = cast(
+            Any,
+            BodyDependency(
+                Role, Role.id, session_dep=MockSessionDep, body_field="role_id"
+            ),
+        )
+        result = await dep.dependency(session=db_session, role_id=role.id)
+
+        assert result.id == role.id
+        assert result.name == "body_annotated_role"