refactor: repository get by id mixin

repositories/mixins.py

@@ -1,5 +1,6 @@
-from typing import Generic, TypeVar, Type
+from typing import Generic, TypeVar, Type, Optional
 
+from sqlalchemy import select, Select
 from sqlalchemy.ext.asyncio import AsyncSession
 
 EntityType = TypeVar("EntityType")
@@ -26,8 +27,7 @@ class RepDeleteMixin(RepBaseMixin[EntityType]):
         await self.session.commit()
 
 
-class RepCreateMixin(Generic[EntityType, CreateType]):
-    session: AsyncSession
+class RepCreateMixin(RepBaseMixin[EntityType], Generic[EntityType, CreateType]):
     entity_class: Type[EntityType]
 
     async def create(self, data: CreateType) -> int:
@@ -36,3 +36,19 @@ class RepCreateMixin(Generic[EntityType, CreateType]):
         await self.session.commit()
         await self.session.refresh(obj)
         return obj.id
+
+
+class GetByIdMixin(RepBaseMixin[EntityType]):
+    entity_class: Type[EntityType]
+
+    def _process_get_by_id_stmt(self, stmt: Select) -> Select:
+        return stmt
+
+    async def get_by_id(self, item_id: int) -> Optional[EntityType]:
+        stmt = select(self.entity_class).where(self.entity_class.id == item_id)
+        if hasattr(self, "is_deleted"):
+            stmt = stmt.where(self.entity_class.is_deleted.is_(False))
+
+        stmt = self._process_get_by_id_stmt(stmt)
+        result = await self.session.execute(stmt)
+        return result.scalar_one_or_none()