fix: added getitem method to relation proxy model

ormar/relations/relation_proxy.py

@@ -1,4 +1,13 @@
-from typing import Any, Generic, List, Optional, TYPE_CHECKING, Type, TypeVar
+from typing import (
+    Any,
+    Generic,
+    List,
+    Optional,
+    TYPE_CHECKING,
+    Type,
+    TypeVar,
+    Union,
+)
 
 import ormar
 from ormar.exceptions import NoMatch, RelationshipInstanceError
@@ -52,8 +61,18 @@ def related_field_name(self) -> str:
 
         return self._related_field_name
 
-    def __getitem__(self, item: Any) -> "T":  # type: ignore
-        return super().__getitem__(item)
+    def __getitem__(self, key: Union[int, slice]) -> "QuerysetProxy[T]":
+        """
+        You can slice the results to desired number of parent models.
+
+        Actual call delegated to QuerySet.
+
+        :param key: numbers of models to slicing
+        :type key: int | slice
+        :return: QuerysetProxy
+        :rtype: QuerysetProxy
+        """
+        return self.queryset_proxy[key]
 
     def __getattribute__(self, item: str) -> Any:
         """

tests/test_queries/test_pagination.py

@@ -180,16 +180,16 @@ async def test_slice_getitem_queryset_on_proxy():
                 c = await Car(name=f"{i}").save()
                 await user.cars.add(c)
 
-            cars_page1 = user.cars[:5]
-            assert len(cars_page1) == 5
-            assert cars_page1[0].name == "0"
-            assert cars_page1[4].name == "4"
+            await user.cars[:5].all()
+            assert len(user.cars) == 5
+            assert user.cars[0].name == "0"
+            assert user.cars[4].name == "4"
 
-            cars_page2 = user.cars[5:10]
-            assert len(cars_page2) == 5
-            assert cars_page2[0].name == "5"
-            assert cars_page2[4].name == "9"
+            await user.cars[5:10].all()
+            assert len(user.cars) == 5
+            assert user.cars[0].name == "5"
+            assert user.cars[4].name == "9"
 
-            cars_page3 = user.cars[10:]
-            assert len(cars_page3) == 10
-            assert cars_page3[0].name == "10"
+            await user.cars[10:].all()
+            assert len(user.cars) == 10
+            assert user.cars[0].name == "10"