Move page settings to property

Author: TheSuperiorStanislav

rest_framework/pagination.py

@@ -169,9 +169,6 @@ class PageNumberPagination(BasePagination):
     http://api.example.org/accounts/?page=4
     http://api.example.org/accounts/?page=4&page_size=100
     """
-    # The default page size.
-    # Defaults to `None`, meaning pagination is disabled.
-    page_size = api_settings.PAGE_SIZE
 
     django_paginator_class = DjangoPaginator
 
@@ -184,18 +181,33 @@ class PageNumberPagination(BasePagination):
     page_size_query_param = None
     page_size_query_description = _('Number of results to return per page.')
 
-    # Set to an integer to limit the maximum page size the client may request.
-    # Only relevant if 'page_size_query_param' has also been set.
-    # Defaults to `None`, meaning page size is unlimited.
-    # It's recommended that you would set a limit to avoid api abuse.
-    max_page_size = api_settings.MAX_PAGE_SIZE
-
     last_page_strings = ('last',)
 
     template = 'rest_framework/pagination/numbers.html'
 
     invalid_page_message = _('Invalid page.')
 
+    @property
+    def page_size(self) -> int:
+        """Get default page size.
+
+        Defaults to `None`, meaning pagination is disabled.
+
+        """
+        return api_settings.PAGE_SIZE
+
+    @property
+    def max_page_size(self) -> int:
+        """Limit page size.
+
+        Set to an integer to limit the maximum page size the client may request.
+        Only relevant if 'page_size_query_param' has also been set.
+        Defaults to `None`, meaning page size is unlimited.
+        It's recommended that you would set a limit to avoid api abuse.
+
+        """
+        return api_settings.MAX_PAGE_SIZE
+
     def paginate_queryset(self, queryset, request, view=None):
         """
         Paginate a queryset if required, either returning a
@@ -379,14 +391,33 @@ class LimitOffsetPagination(BasePagination):
     http://api.example.org/accounts/?limit=100
     http://api.example.org/accounts/?offset=400&limit=100
     """
-    default_limit = api_settings.PAGE_SIZE
     limit_query_param = 'limit'
     limit_query_description = _('Number of results to return per page.')
     offset_query_param = 'offset'
     offset_query_description = _('The initial index from which to return the results.')
-    max_limit = api_settings.MAX_PAGE_SIZE
     template = 'rest_framework/pagination/numbers.html'
 
+    @property
+    def max_limit(self) -> int:
+        """Limit maximum page size.
+
+        Set to an integer to limit the maximum page size the client may request.
+        Only relevant if 'page_size_query_param' has also been set.
+        Defaults to `None`, meaning page size is unlimited.
+        It's recommended that you would set a limit to avoid api abuse.
+
+        """
+        return api_settings.MAX_PAGE_SIZE
+
+    @property
+    def default_limit(self) -> int:
+        """Get default page size.
+
+        Defaults to `None`, meaning pagination is disabled.
+
+        """
+        return api_settings.PAGE_SIZE
+
     def paginate_queryset(self, queryset, request, view=None):
         self.request = request
         self.limit = self.get_limit(request)
@@ -590,7 +621,6 @@ class CursorPagination(BasePagination):
     """
     cursor_query_param = 'cursor'
     cursor_query_description = _('The pagination cursor value.')
-    page_size = api_settings.PAGE_SIZE
     invalid_cursor_message = _('Invalid cursor')
     ordering = '-created'
     template = 'rest_framework/pagination/previous_and_next.html'
@@ -600,16 +630,33 @@ class CursorPagination(BasePagination):
     page_size_query_param = None
     page_size_query_description = _('Number of results to return per page.')
 
-    # Set to an integer to limit the maximum page size the client may request.
-    # Only relevant if 'page_size_query_param' has also been set.
-    max_page_size = api_settings.MAX_PAGE_SIZE
-
     # The offset in the cursor is used in situations where we have a
     # nearly-unique index. (Eg millisecond precision creation timestamps)
     # We guard against malicious users attempting to cause expensive database
     # queries, by having a hard cap on the maximum possible size of the offset.
     offset_cutoff = 1000
 
+    @property
+    def page_size(self) -> int:
+        """Get default page size.
+
+        Defaults to `None`, meaning pagination is disabled.
+
+        """
+        return api_settings.PAGE_SIZE
+
+    @property
+    def max_page_size(self) -> int:
+        """Limit page size.
+
+        Set to an integer to limit the maximum page size the client may request.
+        Only relevant if 'page_size_query_param' has also been set.
+        Defaults to `None`, meaning page size is unlimited.
+        It's recommended that you would set a limit to avoid api abuse.
+
+        """
+        return api_settings.MAX_PAGE_SIZE
+
     def paginate_queryset(self, queryset, request, view=None):
         self.request = request
         self.page_size = self.get_page_size(request)

tests/test_pagination.py

@@ -1,7 +1,7 @@
 import pytest
 from django.core.paginator import Paginator as DjangoPaginator
 from django.db import models
-from django.test import TestCase
+from django.test import TestCase, override_settings
 
 from rest_framework import (
     exceptions, filters, generics, pagination, serializers, status
@@ -135,6 +135,77 @@ def test_404_not_found_for_invalid_page(self):
         }
 
 
+class TestPaginationSettingsIntegration:
+    """
+    Integration tests for pagination settings.
+    """
+
+    def setup_method(self):
+        class PassThroughSerializer(serializers.BaseSerializer):
+            def to_representation(self, item):
+                return item
+
+        class EvenItemsOnly(filters.BaseFilterBackend):
+            def filter_queryset(self, request, queryset, view):
+                return [item for item in queryset if item % 2 == 0]
+
+        class BasicPagination(pagination.PageNumberPagination):
+            page_size_query_param = 'page_size'
+
+        self.view = generics.ListAPIView.as_view(
+            serializer_class=PassThroughSerializer,
+            queryset=range(1, 101),
+            filter_backends=[EvenItemsOnly],
+            pagination_class=BasicPagination
+        )
+
+    @override_settings(
+        REST_FRAMEWORK={
+            "MAX_PAGE_SIZE": 20,
+            "PAGE_SIZE": 5,
+        }
+    )
+    def test_setting_page_size_over_maximum(self):
+        """
+        When page_size parameter exceeds maximum allowable,
+        then it should be capped to the maximum.
+        """
+        request = factory.get('/', {'page_size': 1000})
+        response = self.view(request)
+        assert response.status_code == status.HTTP_200_OK
+        assert len(response.data["results"]) == 20, response.data
+        assert response.data == {
+            'results': [
+                2, 4, 6, 8, 10, 12, 14, 16, 18, 20,
+                22, 24, 26, 28, 30, 32, 34, 36, 38, 40
+            ],
+            'previous': None,
+            'next': 'http://testserver/?page=2&page_size=1000',
+            'count': 50
+        }
+
+    @override_settings(
+        REST_FRAMEWORK={
+            "MAX_PAGE_SIZE": 20,
+            "PAGE_SIZE": 5,
+        }
+    )
+    def test_setting_page_size_to_zero(self):
+        """
+        When page_size parameter is invalid it should return to the default.
+        """
+        request = factory.get('/', {'page_size': 0})
+        response = self.view(request)
+        assert response.status_code == status.HTTP_200_OK
+        assert len(response.data["results"]) == 5, response.data
+        assert response.data == {
+            'results': [2, 4, 6, 8, 10],
+            'previous': None,
+            'next': 'http://testserver/?page=2&page_size=0',
+            'count': 50
+        }
+
+
 class TestPaginationDisabledIntegration:
     """
     Integration tests for disabled pagination.