feat: add AsyncCrud subclass style and base_class param to CrudFactory (#132)

src/fastapi_toolsets/crud/factory.py

@@ -82,6 +82,26 @@ class AsyncCrud(Generic[ModelType]):
     default_load_options: ClassVar[Sequence[ExecutableOption] | None] = None
     cursor_column: ClassVar[Any | None] = None
 
+    @classmethod
+    def __init_subclass__(cls, **kwargs: Any) -> None:
+        super().__init_subclass__(**kwargs)
+        if "model" not in cls.__dict__:
+            return
+        model: type[DeclarativeBase] = cls.__dict__["model"]
+        pk_key = model.__mapper__.primary_key[0].key
+        assert pk_key is not None
+        pk_col = getattr(model, pk_key)
+
+        raw_fields: Sequence[SearchFieldType] | None = cls.__dict__.get(
+            "searchable_fields", None
+        )
+        if raw_fields is None:
+            cls.searchable_fields = [pk_col]
+        else:
+            existing_keys = {f.key for f in raw_fields if not isinstance(f, tuple)}
+            if pk_key not in existing_keys:
+                cls.searchable_fields = [pk_col, *raw_fields]
+
     @classmethod
     def _resolve_load_options(
         cls, load_options: Sequence[ExecutableOption] | None
@@ -1108,6 +1128,7 @@ class AsyncCrud(Generic[ModelType]):
 def CrudFactory(
     model: type[ModelType],
     *,
+    base_class: type[AsyncCrud[Any]] = AsyncCrud,
     searchable_fields: Sequence[SearchFieldType] | None = None,
     facet_fields: Sequence[FacetFieldType] | None = None,
     order_fields: Sequence[QueryableAttribute[Any]] | None = None,
@@ -1119,6 +1140,9 @@ def CrudFactory(
 
     Args:
         model: SQLAlchemy model class
+        base_class: Optional base class to inherit from instead of ``AsyncCrud``.
+            Use this to share custom methods across multiple CRUD classes while
+            still using the factory shorthand.
         searchable_fields: Optional list of searchable fields
         facet_fields: Optional list of columns to compute distinct values for in paginated
             responses. Supports direct columns (``User.status``) and relationship tuples
@@ -1209,28 +1233,27 @@ def CrudFactory(
             joins=[(Post, Post.user_id == User.id)],
             outer_join=True,
         )
+
+        # With a shared custom base class:
+        from typing import Generic, TypeVar
+        from sqlalchemy.orm import DeclarativeBase
+
+        T = TypeVar("T", bound=DeclarativeBase)
+
+        class AuditedCrud(AsyncCrud[T], Generic[T]):
+            @classmethod
+            async def get_active(cls, session):
+                return await cls.get_multi(session, filters=[cls.model.is_active == True])
+
+        UserCrud = CrudFactory(User, base_class=AuditedCrud)
         ```
     """
-    pk_key = model.__mapper__.primary_key[0].key
-    assert pk_key is not None
-    pk_col = getattr(model, pk_key)
-
-    if searchable_fields is None:
-        effective_searchable = [pk_col]
-    else:
-        existing_keys = {f.key for f in searchable_fields if not isinstance(f, tuple)}
-        effective_searchable = (
-            [pk_col, *searchable_fields]
-            if pk_key not in existing_keys
-            else list(searchable_fields)
-        )
-
     cls = type(
         f"Async{model.__name__}Crud",
-        (AsyncCrud,),
+        (base_class,),
         {
             "model": model,
-            "searchable_fields": effective_searchable,
+            "searchable_fields": searchable_fields,
             "facet_fields": facet_fields,
             "order_fields": order_fields,
             "m2m_fields": m2m_fields,