add interface adapters for db

src/interface_adapters/cart_database_interface.py

@@ -0,0 +1,8 @@
+from typing import Optional, List
+
+class CartDatabaseInterface:
+    def fetch_cart_items(self, user_id: int) -> Optional[List[dict]]:
+        """
+        Abstract method to fetch cart items from the database for a given user ID.
+        """
+        raise NotImplementedError("fetch_cart_items must be implemented by a subclass")

src/interface_adapters/cart_repository.py

@@ -0,0 +1,13 @@
+#python imports
+from typing import Optional, List
+
+#dependency imports
+from use_cases.cart_repository_interface import CartRepositoryInterface
+from interface_adapters.cart_database_interface import CartDatabaseInterface
+
+class CartRepository(CartRepositoryInterface):
+    def __init__(self, database_gateway: CartDatabaseInterface):
+        self.database_gateway = database_gateway
+
+    def fetch_cart_by_user_id(self, user_id: int) -> Optional[List[dict]]:
+        return self.database_gateway.fetch_cart_items(user_id)