[feature] Added OpenWispPagination class with suitable default values

Author: pushpit kamboj

docs/developer/other-utilities.rst

@@ -83,6 +83,45 @@ Every openwisp module which has an API should use this class to configure
 its own default settings, which will be merged with the settings of the
 other modules.
 
+``openwisp_utils.api.pagination.OpenWispPagination``
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+A reusable pagination class for DRF views that provides consistent
+pagination behavior across OpenWISP modules with sensible defaults.
+
+- **10** items per page (``page_size``)
+- **100** max items per page (``max_page_size``)
+- Custom page size via ``?page_size=N`` query parameter
+
+**Usage in Views:**
+
+.. code-block:: python
+
+    from openwisp_utils.api.pagination import OpenWispPagination
+    from rest_framework.viewsets import ModelViewSet
+
+
+    class DeviceViewSet(ModelViewSet):
+        queryset = Device.objects.all()
+        serializer_class = DeviceSerializer
+        pagination_class = OpenWispPagination
+
+**API Request Examples:**
+
+.. code-block:: bash
+
+    # Returns first 10 items (default page size)
+    GET /api/v1/controller/devices/
+
+    # Returns items 11-20 (second page)
+    GET /api/v1/controller/devices/?page=2
+
+    # Returns first 25 items (custom page size)
+    GET /api/v1/controller/devices/?page_size=25
+
+    # Returns items 26-50 with custom page size
+    GET /api/v1/controller/devices/?page=2&page_size=25
+
 Storage Utilities
 -----------------
 

openwisp_utils/api/pagination.py

@@ -0,0 +1,17 @@
+from django.core.exceptions import ImproperlyConfigured
+
+try:
+    from rest_framework.pagination import PageNumberPagination
+except ImportError:  # pragma: nocover
+    raise ImproperlyConfigured(
+        "Django REST Framework is required to use "
+        "this feature but it is not installed"
+    )
+
+
+class OpenWispPagination(PageNumberPagination):
+    """Reusable pagination class with sensible defaults."""
+
+    page_size = 10
+    max_page_size = 100
+    page_size_query_param = "page_size"

tests/test_project/tests/test_api.py

@@ -1,6 +1,10 @@
 from django.conf import settings
 from django.core.exceptions import ValidationError
 from django.test import TestCase
+from openwisp_utils.api.pagination import OpenWispPagination
+from rest_framework.pagination import PageNumberPagination
+from rest_framework.request import Request
+from rest_framework.test import APIRequestFactory
 from test_project.serializers import ShelfSerializer
 
 from ..models import Shelf
@@ -64,3 +68,60 @@ def test_rest_framework_settings_override(self):
                 "TEST": True,
             },
         )
+
+
+class TestOpenWispPagination(CreateMixin, TestCase):
+    shelf_model = Shelf
+
+    def setUp(self):
+        self.factory = APIRequestFactory()
+        self.pagination = OpenWispPagination()
+        for i in range(15):
+            self._create_shelf(name=f"shelf{i}")
+
+    def _get_request(self, path="/api/shelves/", data=None):
+        return Request(self.factory.get(path, data))
+
+    def test_inheritance(self):
+        self.assertIsInstance(self.pagination, PageNumberPagination)
+
+    def test_default_attributes(self):
+        self.assertEqual(self.pagination.page_size, 10)
+        self.assertEqual(self.pagination.max_page_size, 100)
+        self.assertEqual(self.pagination.page_size_query_param, "page_size")
+
+    def test_paginate_queryset(self):
+        request = self._get_request()
+        queryset = Shelf.objects.all().order_by("id")
+        paginated = self.pagination.paginate_queryset(queryset, request)
+        self.assertEqual(len(paginated), 10)
+
+    def test_paginate_queryset_second_page(self):
+        request = self._get_request(data={"page": 2})
+        queryset = Shelf.objects.all().order_by("id")
+        paginated = self.pagination.paginate_queryset(queryset, request)
+        self.assertEqual(len(paginated), 5)
+
+    def test_paginate_queryset_custom_page_size(self):
+        request = self._get_request(data={"page_size": 5})
+        queryset = Shelf.objects.all().order_by("id")
+        paginated = self.pagination.paginate_queryset(queryset, request)
+        self.assertEqual(len(paginated), 5)
+
+    def test_paginate_queryset_respects_max_page_size(self):
+        self.pagination.max_page_size = 10
+        request = self._get_request(data={"page_size": 100})
+        queryset = Shelf.objects.all().order_by("id")
+        paginated = self.pagination.paginate_queryset(queryset, request)
+        self.assertEqual(len(paginated), 10)
+
+    def test_get_paginated_response(self):
+        request = self._get_request()
+        queryset = Shelf.objects.all().order_by("id")
+        self.pagination.paginate_queryset(queryset, request)
+        response = self.pagination.get_paginated_response([])
+        self.assertIn("count", response.data)
+        self.assertIn("next", response.data)
+        self.assertIn("previous", response.data)
+        self.assertIn("results", response.data)
+        self.assertEqual(response.data["count"], 15)