From 228406e64a744fd2ae171d361a74116fcc7ed003 Mon Sep 17 00:00:00 2001
From: no-dap <somniholic@naver.com>
Date: Sat, 21 Sep 2019 15:31:03 +0900
Subject: [PATCH] Adding paginate decorator

---
 rest_framework/decorators.py | 29 +++++++++++++++++++++
 tests/test_decorators.py     | 49 +++++++++++++++++++++++++++++-------
 2 files changed, 69 insertions(+), 9 deletions(-)

diff --git a/rest_framework/decorators.py b/rest_framework/decorators.py
index eb1cad9e4..e1f2341e2 100644
--- a/rest_framework/decorators.py
+++ b/rest_framework/decorators.py
@@ -212,3 +212,32 @@ class MethodMapper(dict):
 
     def trace(self, func):
         return self._map('trace', func)
+
+
+def paginate(pagination_class=None, **kwargs):
+    """
+    Decorator that adds a pagination_class to GenericViewSet class.
+    Custom pagination class also available.
+
+    Usage :
+    from rest_framework.pagination import CursorPagination
+
+    @paginate(pagination_class=CursorPagination, page_size=5, ordering='-created_at')
+    class FooViewSet(viewsets.GenericViewSet):
+        ...
+
+    """
+    assert pagination_class is not None, (
+        "@paginate missing required argument: 'pagination_class'"
+    )
+
+    class _Pagination(pagination_class):
+        def __init__(self):
+            self.__dict__.update(kwargs)
+            super(_Pagination, self).__init__()
+
+    def decorator(_class):
+        _class.pagination_class = _Pagination
+        return _class
+
+    return decorator
diff --git a/tests/test_decorators.py b/tests/test_decorators.py
index e10f0e5c5..af6f2af9c 100644
--- a/tests/test_decorators.py
+++ b/tests/test_decorators.py
@@ -1,12 +1,13 @@
 import pytest
 from django.test import TestCase
 
-from rest_framework import status
+from rest_framework import pagination, status, viewsets
 from rest_framework.authentication import BasicAuthentication
 from rest_framework.decorators import (
-    action, api_view, authentication_classes, parser_classes,
+    action, api_view, authentication_classes, paginate, parser_classes,
     permission_classes, renderer_classes, schema, throttle_classes
 )
+from rest_framework.pagination import BasePagination
 from rest_framework.parsers import JSONParser
 from rest_framework.permissions import IsAuthenticated
 from rest_framework.renderers import JSONRenderer
@@ -49,7 +50,6 @@ class DecoratorTestCase(TestCase):
                 return Response()
 
     def test_calling_method(self):
-
         @api_view(['GET'])
         def view(request):
             return Response({})
@@ -63,7 +63,6 @@ class DecoratorTestCase(TestCase):
         assert response.status_code == status.HTTP_405_METHOD_NOT_ALLOWED
 
     def test_calling_put_method(self):
-
         @api_view(['GET', 'PUT'])
         def view(request):
             return Response({})
@@ -77,7 +76,6 @@ class DecoratorTestCase(TestCase):
         assert response.status_code == status.HTTP_405_METHOD_NOT_ALLOWED
 
     def test_calling_patch_method(self):
-
         @api_view(['GET', 'PATCH'])
         def view(request):
             return Response({})
@@ -91,7 +89,6 @@ class DecoratorTestCase(TestCase):
         assert response.status_code == status.HTTP_405_METHOD_NOT_ALLOWED
 
     def test_renderer_classes(self):
-
         @api_view(['GET'])
         @renderer_classes([JSONRenderer])
         def view(request):
@@ -102,7 +99,6 @@ class DecoratorTestCase(TestCase):
         assert isinstance(response.accepted_renderer, JSONRenderer)
 
     def test_parser_classes(self):
-
         @api_view(['GET'])
         @parser_classes([JSONParser])
         def view(request):
@@ -114,7 +110,6 @@ class DecoratorTestCase(TestCase):
         view(request)
 
     def test_authentication_classes(self):
-
         @api_view(['GET'])
         @authentication_classes([BasicAuthentication])
         def view(request):
@@ -126,7 +121,6 @@ class DecoratorTestCase(TestCase):
         view(request)
 
     def test_permission_classes(self):
-
         @api_view(['GET'])
         @permission_classes([IsAuthenticated])
         def view(request):
@@ -156,6 +150,7 @@ class DecoratorTestCase(TestCase):
         """
         Checks CustomSchema class is set on view
         """
+
         class CustomSchema(AutoSchema):
             pass
 
@@ -213,6 +208,7 @@ class ActionDecoratorTestCase(TestCase):
         'name' and 'suffix' are mutually exclusive kwargs used for generating
         a view's display name.
         """
+
         # by default, generate name from method
         @action(detail=True)
         def test_action(request):
@@ -284,3 +280,38 @@ class ActionDecoratorTestCase(TestCase):
             @test_action.mapping.post
             def test_action():
                 raise NotImplementedError
+
+
+class TestPaginateDecorator(TestCase):
+
+    def test_empty_pagination_class(self):
+        msg = "@paginate missing required argument: 'pagination_class'"
+        with self.assertRaisesMessage(AssertionError, msg):
+            @paginate()
+            class MockGenericViewSet(viewsets.GenericViewSet):
+                pass
+
+    def test_adding_page_number_pagination(self):
+        """
+        Other default pagination classes' test result will be same as this even if kwargs changed to anything.
+        """
+
+        @paginate(pagination_class=pagination.PageNumberPagination, page_size=5, ordering='-created_at')
+        class MockGenericViewSet(viewsets.GenericViewSet):
+            pass
+
+        assert hasattr(MockGenericViewSet, 'pagination_class')
+        assert MockGenericViewSet.pagination_class().page_size == 5
+        assert MockGenericViewSet.pagination_class().ordering == '-created_at'
+
+    def test_adding_custom_pagination(self):
+        class CustomPagination(BasePagination):
+            pass
+
+        @paginate(pagination_class=CustomPagination, kwarg1='kwarg1', kwarg2='kwarg2')
+        class MockGenericViewSet(viewsets.GenericViewSet):
+            pass
+
+        assert hasattr(MockGenericViewSet, 'pagination_class')
+        assert MockGenericViewSet.pagination_class().kwarg1 == 'kwarg1'
+        assert MockGenericViewSet.pagination_class().kwarg2 == 'kwarg2'