Merge pull request #389 from d3vyce/388-pathdependency-bodydependency-build-a-bare-unconfigured-crud

fix: PathDependency and BodyDependency build a bare unconfigured CRUD

docs/module/dependencies.md

@@ -62,6 +62,36 @@ async def create_user(body: UserCreateSchema, role: Role = RoleDep):
     ...
 ```
 
+## Eager loading
+
+By default both factories fetch through a bare `CrudFactory(model)`, so relationships are not loaded. Pass `load_options` for a one-off, or `crud` to reuse a CRUD class you already configured:
+
+```python
+from sqlalchemy.orm import selectinload
+
+from fastapi_toolsets.crud import CrudFactory
+from fastapi_toolsets.dependencies import PathDependency
+
+UserDep = PathDependency(
+    model=User,
+    field=User.id,
+    session_dep=get_db,
+    load_options=[selectinload(User.role)],
+)
+
+# Or reuse the app's configured CRUD and its default_load_options
+UserCrud = CrudFactory(User, default_load_options=[selectinload(User.role)])
+UserDep = PathDependency(model=User, field=User.id, session_dep=get_db, crud=UserCrud)
+
+
+@router.get("/users/{user_id}")
+async def get_user(user: User = UserDep):
+    return user.role.name  # already loaded, no extra query
+```
+
+Both parameters work the same way on `BodyDependency`. When given together, the
+usual [relationship loading](crud.md#relationship-loading) precedence applies.
+
 ---
 
 [:material-api: API Reference](../reference/dependencies.md)

src/fastapi_toolsets/dependencies.py

@@ -2,14 +2,15 @@
 
 import inspect
 import typing
-from collections.abc import Callable
+from collections.abc import Callable, Sequence
 from typing import Any, cast
 
 from fastapi import Depends
 from fastapi.params import Depends as DependsClass
 from sqlalchemy.ext.asyncio import AsyncSession
+from sqlalchemy.sql.base import ExecutableOption
 
-from .crud import CrudFactory
+from .crud import AsyncCrud, CrudFactory
 from .types import ModelType, SessionDependency
 
 __all__ = ["BodyDependency", "PathDependency"]
@@ -24,12 +25,59 @@ def _unwrap_session_dep(session_dep: SessionDependency) -> Callable[..., Any]:
     return session_dep
 
 
+def _fetch_dependency(
+    model: type[ModelType],
+    field: Any,
+    *,
+    session_dep: SessionDependency,
+    param_name: str,
+    crud: type[AsyncCrud[ModelType]] | None,
+    load_options: Sequence[ExecutableOption] | None,
+) -> ModelType:
+    """Build a Depends() that fetches one row by ``field == <param_name>``."""
+    session_callable = _unwrap_session_dep(session_dep)
+    if crud is not None and crud.model is not model:
+        raise ValueError(
+            f"crud is bound to {crud.model.__name__}, not {model.__name__}"
+        )
+    crud = crud or CrudFactory(model)
+
+    # `session` has no default here: the __signature__ override below is what
+    # FastAPI reads, and it always passes `session` explicitly.
+    async def dependency(session: AsyncSession, **kwargs: Any) -> ModelType:
+        return await crud.get(
+            session,
+            filters=[field == kwargs[param_name]],
+            load_options=load_options,
+        )
+
+    dependency.__signature__ = inspect.Signature(  # ty:ignore[unresolved-attribute]
+        parameters=[
+            inspect.Parameter(
+                param_name,
+                inspect.Parameter.KEYWORD_ONLY,
+                annotation=field.type.python_type,
+            ),
+            inspect.Parameter(
+                "session",
+                inspect.Parameter.KEYWORD_ONLY,
+                annotation=AsyncSession,
+                default=Depends(session_callable),
+            ),
+        ]
+    )
+
+    return cast(ModelType, Depends(cast(Callable[..., ModelType], dependency)))
+
+
 def PathDependency(
     model: type[ModelType],
     field: Any,
     *,
     session_dep: SessionDependency,
     param_name: str | None = None,
+    crud: type[AsyncCrud[ModelType]] | None = None,
+    load_options: Sequence[ExecutableOption] | None = None,
 ) -> ModelType:
     """Create a dependency that fetches a DB object from a path parameter.
 
@@ -38,6 +86,10 @@ def PathDependency(
         field: Model field to filter by (e.g., User.id)
         session_dep: Session dependency function (e.g., get_db)
         param_name: Path parameter name (defaults to model_field, e.g., user_id)
+        crud: Existing CRUD class to fetch with, so its ``default_load_options``
+            apply. Defaults to a bare ``CrudFactory(model)``.
+        load_options: SQLAlchemy loader options for the fetch. Overrides the CRUD's
+            ``default_load_options`` entirely rather than merging with them.
 
     Returns:
         A Depends() instance that resolves to the model instance
@@ -55,36 +107,14 @@ def PathDependency(
         ): ...
         ```
     """
-    session_callable = _unwrap_session_dep(session_dep)
+    return _fetch_dependency(
-    crud = CrudFactory(model)
+        model,
-    name = (
+        field,
-        param_name
+        session_dep=session_dep,
-        if param_name is not None
+        param_name=param_name or f"{model.__name__.lower()}_{field.key}",
-        else f"{model.__name__.lower()}_{field.key}"
+        crud=crud,
+        load_options=load_options,
     )
-    python_type = field.type.python_type
-
-    async def dependency(
-        session: AsyncSession = Depends(session_callable), **kwargs: Any
-    ) -> ModelType:
-        value = kwargs[name]
-        return await crud.get(session, filters=[field == value])
-
-    dependency.__signature__ = inspect.Signature(  # ty:ignore[unresolved-attribute]
-        parameters=[
-            inspect.Parameter(
-                name, inspect.Parameter.KEYWORD_ONLY, annotation=python_type
-            ),
-            inspect.Parameter(
-                "session",
-                inspect.Parameter.KEYWORD_ONLY,
-                annotation=AsyncSession,
-                default=Depends(session_callable),
-            ),
-        ]
-    )
-
-    return cast(ModelType, Depends(cast(Callable[..., ModelType], dependency)))
 
 
 def BodyDependency(
@@ -93,6 +123,8 @@ def BodyDependency(
     *,
     session_dep: SessionDependency,
     body_field: str,
+    crud: type[AsyncCrud[ModelType]] | None = None,
+    load_options: Sequence[ExecutableOption] | None = None,
 ) -> ModelType:
     """Create a dependency that fetches a DB object from a body field.
 
@@ -101,6 +133,10 @@ def BodyDependency(
         field: Model field to filter by (e.g., User.id)
         session_dep: Session dependency function (e.g., get_db)
         body_field: Name of the field in the request body
+        crud: Existing CRUD class to fetch with, so its ``default_load_options``
+            apply. Defaults to a bare ``CrudFactory(model)``.
+        load_options: SQLAlchemy loader options for the fetch. Overrides the CRUD's
+            ``default_load_options`` entirely rather than merging with them.
 
     Returns:
         A Depends() instance that resolves to the model instance
@@ -120,28 +156,11 @@ def BodyDependency(
         ): ...
         ```
     """
-    session_callable = _unwrap_session_dep(session_dep)
+    return _fetch_dependency(
-    crud = CrudFactory(model)
+        model,
-    python_type = field.type.python_type
+        field,
-
+        session_dep=session_dep,
-    async def dependency(
+        param_name=body_field,
-        session: AsyncSession = Depends(session_callable), **kwargs: Any
+        crud=crud,
-    ) -> ModelType:
+        load_options=load_options,
-        value = kwargs[body_field]
-        return await crud.get(session, filters=[field == value])
-
-    dependency.__signature__ = inspect.Signature(  # ty:ignore[unresolved-attribute]
-        parameters=[
-            inspect.Parameter(
-                body_field, inspect.Parameter.KEYWORD_ONLY, annotation=python_type
-            ),
-            inspect.Parameter(
-                "session",
-                inspect.Parameter.KEYWORD_ONLY,
-                annotation=AsyncSession,
-                default=Depends(session_callable),
-            ),
-        ]
     )
-
-    return cast(ModelType, Depends(cast(Callable[..., ModelType], dependency)))

tests/test_dependencies.py

@@ -7,15 +7,18 @@ from typing import Annotated, Any, cast
 
 import pytest
 from fastapi.params import Depends
+from sqlalchemy import inspect as sa_inspect
 from sqlalchemy.ext.asyncio import AsyncSession
+from sqlalchemy.orm import selectinload
 
+from fastapi_toolsets.crud import CrudFactory
 from fastapi_toolsets.dependencies import (
     BodyDependency,
     PathDependency,
     _unwrap_session_dep,
 )
 
-from .conftest import Role, RoleCreate, RoleCrud, User
+from .conftest import Role, RoleCreate, RoleCrud, User, UserCreate, UserCrud
 
 
 async def mock_get_db() -> AsyncGenerator[AsyncSession, None]:
@@ -275,3 +278,78 @@ class TestBodyDependency:
 
         assert result.id == role.id
         assert result.name == "body_annotated_role"
+
+
+class TestDependencyLoadOptions:
+    """Both factories can eager-load relations instead of using a bare CRUD."""
+
+    @staticmethod
+    async def _make_user(db_session):
+        role = await RoleCrud.create(db_session, RoleCreate(name="load_opts_role"))
+        user = await UserCrud.create(
+            db_session,
+            UserCreate(username="load_opts", email="load@opts", role_id=role.id),
+        )
+        db_session.expunge_all()
+        return user
+
+    @pytest.mark.anyio
+    async def test_bare_crud_leaves_relation_unloaded(self, db_session):
+        """Baseline: without options the relation is not loaded (what the ticket reports)."""
+        user = await self._make_user(db_session)
+
+        dep = cast(Any, PathDependency(User, User.id, session_dep=mock_get_db))
+        result = await dep.dependency(session=db_session, user_id=user.id)
+
+        assert "role" in sa_inspect(result).unloaded
+
+    @pytest.mark.anyio
+    async def test_load_options_and_crud_eager_load(self, db_session):
+        """Every way of asking for eager loading, on both factories, actually loads."""
+        user = await self._make_user(db_session)
+        eager = [selectinload(User.role)]
+        eager_crud = CrudFactory(User, default_load_options=eager)
+
+        deps = {
+            "path/load_options": PathDependency(
+                User, User.id, session_dep=mock_get_db, load_options=eager
+            ),
+            "path/crud": PathDependency(
+                User, User.id, session_dep=mock_get_db, crud=eager_crud
+            ),
+            "body/load_options": BodyDependency(
+                User,
+                User.id,
+                session_dep=mock_get_db,
+                body_field="user_id",
+                load_options=eager,
+            ),
+            "body/crud": BodyDependency(
+                User,
+                User.id,
+                session_dep=mock_get_db,
+                body_field="user_id",
+                crud=eager_crud,
+            ),
+        }
+
+        for label, dep in deps.items():
+            # Drop the identity map, or the next fetch reuses the already-loaded
+            # instance and the assertion passes for the wrong reason.
+            db_session.expunge_all()
+            result = await cast(Any, dep).dependency(
+                session=db_session, user_id=user.id
+            )
+
+            assert "role" not in sa_inspect(result).unloaded, label
+            assert result.role.name == "load_opts_role", label
+
+    def test_crud_bound_to_another_model_is_rejected(self):
+        """A crud= for a different model would silently query the wrong table.
+
+        ``ty`` rejects this statically; the runtime guard covers untyped callers.
+        """
+        with pytest.raises(ValueError, match="bound to Role, not User"):
+            PathDependency(
+                User, User.id, session_dep=mock_get_db, crud=cast(Any, RoleCrud)
+            )