[fix] Fixed - Exception raised on opening non existing user ID #228

- Added a test to check the response status on navigating to a non-existing user change page
- Handled exceptions for an invalid UUID and a non-existing user

Fixes #228

openwisp_users/admin.py

@@ -409,8 +409,8 @@ def get_inline_instances(self, request, obj=None):
 
     def change_view(self, request, object_id, form_url='', extra_context=None):
         extra_context = extra_context or {}
-        obj = self.model.objects.get(pk=object_id)
-        if user_not_allowed_to_change_owner(request.user, obj):
+        obj = self.get_object(request, object_id)
+        if (obj is not None) and (user_not_allowed_to_change_owner(request.user, obj)):
             show_owner_warning = True
             extra_context.update({'show_owner_warning': show_owner_warning})
         return super().change_view(request, object_id, form_url, extra_context)

openwisp_users/tests/test_admin.py

@@ -2,6 +2,7 @@
 import os
 import re
 import smtplib
+import uuid
 from unittest.mock import patch
 
 from django.contrib import admin
@@ -169,6 +170,32 @@ def test_admin_change_user_email_empty(self):
         self.assertEqual(len(mail.outbox), 0)
         self.assertContains(response, 'errors field-email')
 
+    def test_admin_change_user_page_get_invalid_UUID(self):
+        admin = self._create_admin()
+        self.client.force_login(admin)
+        with self.subTest('Test for wrong identifier'):
+            response = self.client.get(
+                reverse(f'admin:{self.app_label}_user_change', args=['WRONG']),
+                follow=True,
+            )
+            html = (
+                '<li class="warning">User with ID “WRONG” '
+                + 'doesn’t exist. Perhaps it was deleted?</li>'
+            )
+            self.assertEquals(response.status_code, 200)
+            self.assertContains(response, html)
+        with self.subTest('Test for non-existing user'):
+            id = uuid.uuid4()
+            response = self.client.get(
+                reverse(f'admin:{self.app_label}_user_change', args=[id],), follow=True
+            )
+            html = (
+                f'<li class="warning">User with ID “{id}” '
+                + 'doesn’t exist. Perhaps it was deleted?</li>'
+            )
+            self.assertEquals(response.status_code, 200)
+            self.assertContains(response, html)
+
     def test_organization_view_on_site(self):
         admin = self._create_admin()
         self.client.force_login(admin)