From cd2f70ce10f67b84536f0761be51b070f68fd102 Mon Sep 17 00:00:00 2001
From: Alex Dusenbery <adusenbery@edx.org>
Date: Tue, 30 Apr 2024 12:03:24 -0400
Subject: [PATCH] feat: limit the number of resulting learners in Django admin
 manage learners view

...so that we can support customers with a very large number of learners
ENT-8850
---
 CHANGELOG.rst             |  6 ++++++
 enterprise/__init__.py    |  2 +-
 enterprise/admin/views.py | 36 +++++++++++++++++++++++++-----------
 enterprise/constants.py   |  3 +++
 4 files changed, 35 insertions(+), 12 deletions(-)

diff --git a/CHANGELOG.rst b/CHANGELOG.rst
index 2d1b7b1995..873eee070d 100644
--- a/CHANGELOG.rst
+++ b/CHANGELOG.rst
@@ -15,6 +15,12 @@ Change Log
 
 Unreleased
 ----------
+* nothing unreleased
+
+[4.17.0]
+--------
+* feat: limit the number of resulting learners in Django admin manage learners view
+
 [4.16.5]
 --------
 * feat: splitting out group membership serializer learner id into lms user ID and ecu ID
diff --git a/enterprise/__init__.py b/enterprise/__init__.py
index 14366bd1a1..dc908abd25 100644
--- a/enterprise/__init__.py
+++ b/enterprise/__init__.py
@@ -2,4 +2,4 @@
 Your project description goes here.
 """
 
-__version__ = "4.16.5"
+__version__ = "4.17.0"
diff --git a/enterprise/admin/views.py b/enterprise/admin/views.py
index 9addac150f..635c593c6b 100644
--- a/enterprise/admin/views.py
+++ b/enterprise/admin/views.py
@@ -37,7 +37,7 @@
 from enterprise.api_client.discovery import get_course_catalog_api_service_client
 from enterprise.api_client.ecommerce import EcommerceApiClient
 from enterprise.api_client.sso_orchestrator import EnterpriseSSOOrchestratorApiClient, SsoOrchestratorClientError
-from enterprise.constants import PAGE_SIZE
+from enterprise.constants import DJANGO_ADMIN_MANAGE_LEARNERS_LIMIT, PAGE_SIZE
 from enterprise.errors import LinkUserToEnterpriseError
 from enterprise.models import (
     EnrollmentNotificationEmailTemplate,
@@ -357,7 +357,11 @@ def get_search_keyword(self, request):
 
     def get_enterprise_customer_user_queryset(self, request, search_keyword, customer_uuid, page_size=PAGE_SIZE):
         """
-        Get the list of EnterpriseCustomerUsers we want to render.
+        Get the list of EnterpriseCustomerUsers we want to render. Note that,
+        if no ``search_keyword`` is provided, the resulting queryset will
+        only include up to some constant limit of results, so that we
+        can support searching for particular user records in customers
+        with very large numbers of learners.
 
         Arguments:
             request (HttpRequest): HTTP Request instance.
@@ -367,16 +371,26 @@ def get_enterprise_customer_user_queryset(self, request, search_keyword, custome
             page_size (int): Number of learners displayed in each paginated set.
         """
         page = request.GET.get('page', 1)
-        learners = EnterpriseCustomerUser.objects.filter(enterprise_customer__uuid=customer_uuid)
-        user_ids = learners.values_list('user_id', flat=True)
-        matching_users = User.objects.filter(pk__in=user_ids)
         if search_keyword is not None:
-            matching_users = matching_users.filter(
-                Q(email__icontains=search_keyword) | Q(username__icontains=search_keyword)
-            )
-        matching_user_ids = matching_users.values_list('pk', flat=True)
-        learners = learners.filter(user_id__in=matching_user_ids)
-        return paginated_list(learners, page, page_size)
+            enterprise_learners = self._get_searched_enterprise_customer_users(search_keyword, customer_uuid)
+        else:
+            enterprise_learners = EnterpriseCustomerUser.objects.filter(
+                enterprise_customer__uuid=customer_uuid,
+            )[:DJANGO_ADMIN_MANAGE_LEARNERS_LIMIT]
+        return paginated_list(enterprise_learners, page, page_size)
+
+    def _get_searched_enterprise_customer_users(self, search_keyword, customer_uuid):
+        """
+        Helper to return a paginated list of enterprise customer users
+        who match some search criteria based on corresponding ``core.User`` records.
+        """
+        matching_user_ids = User.objects.filter(
+            Q(email__icontains=search_keyword) | Q(username__icontains=search_keyword)
+        ).values_list('id', flat=True)
+        return EnterpriseCustomerUser.objects.filter(
+            enterprise_customer__uuid=customer_uuid,
+            user_id__in=matching_user_ids,
+        )
 
     def get_pending_users_queryset(self, search_keyword, customer_uuid):
         """
diff --git a/enterprise/constants.py b/enterprise/constants.py
index 15f4ac8ba4..da03e7896d 100644
--- a/enterprise/constants.py
+++ b/enterprise/constants.py
@@ -252,3 +252,6 @@ class FulfillmentTypes:
 )
 
 ENTITY_ID_REGEX = r"<(\w+:)?EntityDescriptor.*?entityID=['\"](.*?)['\"].*?>"
+
+# Max learners included in the Admin Manage Learners page
+DJANGO_ADMIN_MANAGE_LEARNERS_LIMIT = 10000