fix: return empty list when no courses are found for request (#35942)

This change addresses an issue reported while testing Sumac, where the API V2 is on by default in the authoring MFE: openedx/wg-build-test-release#428. It fails when retrieving an empty list of courses with the queryparams api/contentstore/v2/home/courses?page=1&order=display_name. When this was implemented, the course authoring MFE rendered the empty lists only with page=1 query param (didn't do any filtering/ordering by default), which was later changed to page=1&order=display_name which now ordered by default.

This issue occurs because all the filtering and ordering are done under the assumption that course_overviews is always a query set. However, that's only true when there are courses available and CourseOverview.get_all_courses is used. When not, an empty list is returned instead, raising a 500 error in Studio.

cms/djangoapps/contentstore/rest_api/v1/views/tests/test_home.py

@@ -2,7 +2,9 @@
 Unit tests for home page view.
 """
 import ddt
+import pytz
 from collections import OrderedDict
+from datetime import datetime, timedelta
 from django.conf import settings
 from django.test import override_settings
 from django.urls import reverse
@@ -100,12 +102,13 @@ class HomePageCoursesViewTest(CourseTestCase):
     def setUp(self):
         super().setUp()
         self.url = reverse("cms.djangoapps.contentstore:v1:courses")
-        CourseOverviewFactory.create(
+        self.course_overview = CourseOverviewFactory.create(
             id=self.course.id,
             org=self.course.org,
             display_name=self.course.display_name,
             display_number_with_default=self.course.number,
         )
+        self.non_staff_client, _ = self.create_non_staff_authed_user_client()
 
     def test_home_page_response(self):
         """Check successful response content"""
@@ -131,6 +134,7 @@ def test_home_page_response(self):
         print(response.data)
         self.assertDictEqual(expected_response, response.data)
 
+    @override_settings(FEATURES=FEATURES_WITH_HOME_PAGE_COURSE_V2_API)
     def test_home_page_response_with_api_v2(self):
         """Check successful response content with api v2 modifications.
 
@@ -155,12 +159,88 @@ def test_home_page_response_with_api_v2(self):
             "in_process_course_actions": [],
         }
 
-        with override_settings(FEATURES=FEATURES_WITH_HOME_PAGE_COURSE_V2_API):
-            response = self.client.get(self.url)
+        response = self.client.get(self.url)
 
         self.assertEqual(response.status_code, status.HTTP_200_OK)
         self.assertDictEqual(expected_response, response.data)
 
+    @override_settings(FEATURES=FEATURES_WITH_HOME_PAGE_COURSE_V2_API)
+    @ddt.data(
+        ("active_only", "true", 2, 0),
+        ("archived_only", "true", 0, 1),
+        ("search", "sample", 1, 0),
+        ("search", "demo", 0, 1),
+        ("order", "org", 2, 1),
+        ("order", "display_name", 2, 1),
+        ("order", "number", 2, 1),
+        ("order", "run", 2, 1)
+    )
+    @ddt.unpack
+    def test_filter_and_ordering_courses(
+        self,
+        filter_key,
+        filter_value,
+        expected_active_length,
+        expected_archived_length
+    ):
+        """Test home page with org filter and ordering for a staff user.
+
+        The test creates an active/archived course, and then filters/orders them using the query parameters.
+        """
+        archived_course_key = self.store.make_course_key("demo-org", "demo-number", "demo-run")
+        CourseOverviewFactory.create(
+            display_name="Course (Demo)",
+            id=archived_course_key,
+            org=archived_course_key.org,
+            end=(datetime.now() - timedelta(days=365)).replace(tzinfo=pytz.UTC),
+        )
+        active_course_key = self.store.make_course_key("sample-org", "sample-number", "sample-run")
+        CourseOverviewFactory.create(
+            display_name="Course (Sample)",
+            id=active_course_key,
+            org=active_course_key.org,
+        )
+
+        response = self.client.get(self.url, {filter_key: filter_value})
+
+        self.assertEqual(response.status_code, status.HTTP_200_OK)
+        self.assertEqual(len(response.data["archived_courses"]), expected_archived_length)
+        self.assertEqual(len(response.data["courses"]), expected_active_length)
+
+    @override_settings(FEATURES=FEATURES_WITH_HOME_PAGE_COURSE_V2_API)
+    @ddt.data(
+        ("active_only", "true"),
+        ("archived_only", "true"),
+        ("search", "sample"),
+        ("order", "org"),
+    )
+    @ddt.unpack
+    def test_filter_and_ordering_no_courses_staff(self, filter_key, filter_value):
+        """Test home page with org filter and ordering when there are no courses for a staff user."""
+        self.course_overview.delete()
+
+        response = self.client.get(self.url, {filter_key: filter_value})
+
+        self.assertEqual(len(response.data["courses"]), 0)
+        self.assertEqual(response.status_code, status.HTTP_200_OK)
+
+    @override_settings(FEATURES=FEATURES_WITH_HOME_PAGE_COURSE_V2_API)
+    @ddt.data(
+        ("active_only", "true"),
+        ("archived_only", "true"),
+        ("search", "sample"),
+        ("order", "org"),
+    )
+    @ddt.unpack
+    def test_home_page_response_no_courses_non_staff(self, filter_key, filter_value):
+        """Test home page with org filter and ordering when there are no courses for a non-staff user."""
+        self.course_overview.delete()
+
+        response = self.non_staff_client.get(self.url)
+
+        self.assertEqual(len(response.data["courses"]), 0)
+        self.assertEqual(response.status_code, status.HTTP_200_OK)
+
     @override_waffle_switch(ENABLE_GLOBAL_STAFF_OPTIMIZATION, True)
     def test_org_query_if_passed(self):
         """Test home page when org filter passed as a query param"""

cms/djangoapps/contentstore/rest_api/v2/views/tests/test_home.py

@@ -45,6 +45,7 @@ def setUp(self):
             org=archived_course_key.org,
             end=(datetime.now() - timedelta(days=365)).replace(tzinfo=pytz.UTC),
         )
+        self.non_staff_client, _ = self.create_non_staff_authed_user_client()
 
     def test_home_page_response(self):
         """Get list of courses available to the logged in user.
@@ -247,3 +248,100 @@ def test_api_v2_is_disabled(self, mock_modulestore, mock_course_overview):
         self.assertEqual(response.status_code, status.HTTP_200_OK)
         mock_modulestore().get_course_summaries.assert_called_once()
         mock_course_overview.get_all_courses.assert_not_called()
+
+    @ddt.data(
+        ("active_only", "true"),
+        ("archived_only", "true"),
+        ("search", "sample"),
+        ("order", "org"),
+        ("page", 1),
+    )
+    @ddt.unpack
+    def test_if_empty_list_of_courses(self, query_param, value):
+        """Get list of courses when no courses are available.
+
+        Expected result:
+        - An empty list of courses available to the logged in user.
+        """
+        self.active_course.delete()
+        self.archived_course.delete()
+
+        response = self.client.get(self.api_v2_url, {query_param: value})
+
+        self.assertEqual(len(response.data['results']['courses']), 0)
+        self.assertEqual(response.status_code, status.HTTP_200_OK)
+
+    @override_settings(FEATURES=FEATURES_WITH_HOME_PAGE_COURSE_V2_API)
+    @ddt.data(
+        ("active_only", "true", 2, 0),
+        ("archived_only", "true", 0, 1),
+        ("search", "foo", 1, 0),
+        ("search", "demo", 0, 1),
+        ("order", "org", 2, 1),
+        ("order", "display_name", 2, 1),
+        ("order", "number", 2, 1),
+        ("order", "run", 2, 1)
+    )
+    @ddt.unpack
+    def test_filter_and_ordering_courses(
+        self,
+        filter_key,
+        filter_value,
+        expected_active_length,
+        expected_archived_length
+    ):
+        """Get list of courses when filter and ordering are applied.
+
+        This test creates two courses besides the default courses created in the setUp method.
+        Then filters and orders them based on the filter_key and filter_value passed as query parameters.
+
+        Expected result:
+        - A list of courses available to the logged in user for the specified filter and order.
+        """
+        archived_course_key = self.store.make_course_key("demo-org", "demo-number", "demo-run")
+        CourseOverviewFactory.create(
+            display_name="Course (Demo)",
+            id=archived_course_key,
+            org=archived_course_key.org,
+            end=(datetime.now() - timedelta(days=365)).replace(tzinfo=pytz.UTC),
+        )
+        active_course_key = self.store.make_course_key("foo-org", "foo-number", "foo-run")
+        CourseOverviewFactory.create(
+            display_name="Course (Foo)",
+            id=active_course_key,
+            org=active_course_key.org,
+        )
+
+        response = self.client.get(self.api_v2_url, {filter_key: filter_value})
+
+        self.assertEqual(response.status_code, status.HTTP_200_OK)
+        self.assertEqual(
+            len([course for course in response.data["results"]["courses"] if course["is_active"]]),
+            expected_active_length
+        )
+        self.assertEqual(
+            len([course for course in response.data["results"]["courses"] if not course["is_active"]]),
+            expected_archived_length
+        )
+
+    @ddt.data(
+        ("active_only", "true"),
+        ("archived_only", "true"),
+        ("search", "sample"),
+        ("order", "org"),
+        ("page", 1),
+    )
+    @ddt.unpack
+    def test_if_empty_list_of_courses_non_staff(self, query_param, value):
+        """Get list of courses when no courses are available for non-staff users.
+
+        Expected result:
+        - An empty list of courses available to the logged in user.
+        """
+        self.active_course.delete()
+        self.archived_course.delete()
+
+        response = self.non_staff_client.get(self.api_v2_url, {query_param: value})
+
+        self.assertEqual(len(response.data["results"]["courses"]), 0)
+        self.assertEqual(response.status_code, status.HTTP_200_OK)

cms/djangoapps/contentstore/views/course.py

@@ -15,6 +15,7 @@
 from django.contrib.auth import get_user_model
 from django.contrib.auth.decorators import login_required
 from django.core.exceptions import FieldError, PermissionDenied, ValidationError as DjangoValidationError
+from django.db.models import QuerySet
 from django.http import Http404, HttpResponse, HttpResponseBadRequest, HttpResponseNotFound
 from django.shortcuts import redirect
 from django.urls import reverse
@@ -575,6 +576,10 @@ def filter_ccx(course_access):
 
     if course_keys:
         courses_list = CourseOverview.get_all_courses(filter_={'id__in': course_keys})
+    else:
+        # If no course keys are found for the current user, then return without filtering
+        # or ordering the courses list.
+        return courses_list, []
 
     search_query, order, active_only, archived_only = get_query_params_if_present(request)
     courses_list = get_filtered_and_ordered_courses(
@@ -588,7 +593,11 @@ def filter_ccx(course_access):
     return courses_list, []
 
 
-def get_courses_by_status(active_only, archived_only, course_overviews):
+def get_courses_by_status(
+    active_only: bool,
+    archived_only: bool,
+    course_overviews: QuerySet[CourseOverview]
+) -> QuerySet[CourseOverview]:
     """
     Return course overviews based on a base queryset filtered by a status.
 
@@ -602,7 +611,10 @@ def get_courses_by_status(active_only, archived_only, course_overviews):
     return CourseOverview.get_courses_by_status(active_only, archived_only, course_overviews)
 
 
-def get_courses_by_search_query(search_query, course_overviews):
+def get_courses_by_search_query(
+    search_query: str | None,
+    course_overviews: QuerySet[CourseOverview]
+) -> QuerySet[CourseOverview]:
     """Return course overviews based on a base queryset filtered by a search query.
 
     Args:
@@ -614,7 +626,10 @@ def get_courses_by_search_query(search_query, course_overviews):
     return CourseOverview.get_courses_matching_query(search_query, course_overviews=course_overviews)
 
 
-def get_courses_order_by(order_query, course_overviews):
+def get_courses_order_by(
+    order_query: str | None,
+    course_overviews: QuerySet[CourseOverview]
+) -> QuerySet[CourseOverview]:
     """Return course overviews based on a base queryset ordered by a query.
 
     Args: