From e543a68990d55324b0e665ae08b09047ff4ac4b8 Mon Sep 17 00:00:00 2001
From: Awais Ansari <79941147+awais-ansari@users.noreply.github.com>
Date: Mon, 3 Jul 2023 13:52:15 +0500
Subject: [PATCH] feat: add pagination in course enrollment list API (#32546)

* feat: add pagination in course enrollment list API

* refactor: enrollment course list API

* refactor: follow best practice in course enrollment list API
---
 .../notifications/tests/test_views.py         |  5 +-
 .../core/djangoapps/notifications/views.py    | 54 ++++++++++++-------
 2 files changed, 38 insertions(+), 21 deletions(-)

diff --git a/openedx/core/djangoapps/notifications/tests/test_views.py b/openedx/core/djangoapps/notifications/tests/test_views.py
index 84f7116964..8bce8898d0 100644
--- a/openedx/core/djangoapps/notifications/tests/test_views.py
+++ b/openedx/core/djangoapps/notifications/tests/test_views.py
@@ -76,9 +76,12 @@ class CourseEnrollmentListViewTest(ModuleStoreTestCase):
         response = self.client.get(url)
 
         self.assertEqual(response.status_code, status.HTTP_200_OK)
+        data = response.data['results']
         enrollments = CourseEnrollment.objects.filter(user=self.user, is_active=True)
         expected_data = NotificationCourseEnrollmentSerializer(enrollments, many=True).data
-        self.assertEqual(response.data, expected_data)
+
+        self.assertEqual(len(data), 1)
+        self.assertEqual(data, expected_data)
 
     def test_course_enrollment_api_permission(self):
         """
diff --git a/openedx/core/djangoapps/notifications/views.py b/openedx/core/djangoapps/notifications/views.py
index 04543dc524..f083649989 100644
--- a/openedx/core/djangoapps/notifications/views.py
+++ b/openedx/core/djangoapps/notifications/views.py
@@ -36,23 +36,31 @@ class CourseEnrollmentListView(generics.ListAPIView):
     API endpoint to get active CourseEnrollments for requester.
 
     **Permissions**: User must be authenticated.
+    **Response Format** (paginated):
 
-    **Response Format**:
-        [
-            {
-                "course": {
-                    "id": (int) course_id,
-                    "display_name": (str) course_display_name
+        {
+            "next": (str) url_to_next_page_of_courses,
+            "previous": (str) url_to_previous_page_of_courses,
+            "count": (int) total_number_of_courses,
+            "num_pages": (int) total_number_of_pages,
+            "current_page": (int) current_page_number,
+            "start": (int) index_of_first_course_on_page,
+            "results" : [
+                {
+                    "course": {
+                        "id": (int) course_id,
+                        "display_name": (str) course_display_name
+                    },
                 },
-            },
-            ...
-        ]
-    **Response Error Codes**:
-            - 403: The requester cannot access resource.
+                ...
+            ],
+        }
+
+    Response Error Codes:
+    - 403: The requester cannot access resource.
     """
     serializer_class = NotificationCourseEnrollmentSerializer
     permission_classes = [permissions.IsAuthenticated]
-    pagination_class = None
 
     def get_queryset(self):
         user = self.request.user
@@ -63,14 +71,20 @@ class CourseEnrollmentListView(generics.ListAPIView):
         Returns the list of active course enrollments for which ENABLE_NOTIFICATIONS
         Waffle flag is enabled
         """
-        enrollment_queryset = self.get_queryset().select_related('course')
-        enrollments = [
-            enrollment
-            for enrollment in enrollment_queryset
-            if ENABLE_NOTIFICATIONS.is_enabled(enrollment.course.id)
-        ]
-        serializer = self.get_serializer(enrollments, many=True)
-        return Response(serializer.data)
+        queryset = self.filter_queryset(self.get_queryset())
+        course_ids = queryset.values_list('course_id', flat=True)
+
+        for course_id in course_ids:
+            if not ENABLE_NOTIFICATIONS.is_enabled(course_id):
+                queryset = queryset.exclude(course_id=course_id)
+
+        queryset = queryset.select_related('course').order_by('-id')
+        page = self.paginate_queryset(queryset)
+        if page is not None:
+            serializer = self.get_serializer(page, many=True)
+            return self.get_paginated_response(serializer.data)
+
+        return Response(self.get_serializer(queryset, many=True).data)
 
 
 class UserNotificationPreferenceView(APIView):