Fixes #20011: UI Error msg for duplicate IDs in bulk import

netbox/dcim/tests/test_views.py

@@ -2322,6 +2322,32 @@ class DeviceTestCase(ViewTestCases.PrimaryObjectViewTestCase):
         url = reverse('dcim:device_inventory', kwargs={'pk': device.pk})
         self.assertHttpStatus(self.client.get(url), 200)
 
+    @override_settings(EXEMPT_VIEW_PERMISSIONS=['*'])
+    def test_bulk_import_duplicate_ids_error_message(self):
+        device = Device.objects.first()
+        csv_data = (
+            "id,role",
+            f"{device.pk},Device Role 1",
+            f"{device.pk},Device Role 2",
+        )
+
+        self.add_permissions('dcim.add_device', 'dcim.change_device')
+        response = self.client.post(
+            self._get_url('bulk_import'),
+            {
+                'data': '\n'.join(csv_data),
+                'format': ImportFormatChoices.CSV,
+                'csv_delimiter': CSVDelimiterChoices.AUTO,
+            },
+            follow=True
+        )
+
+        self.assertEqual(response.status_code, 200)
+        self.assertIn(
+            f'Duplicate objects found: Device with ID(s) {device.pk} appears multiple times',
+            response.content.decode('utf-8')
+        )
+
 
 class ModuleTestCase(
     # Module does not support bulk renaming (no name field) or

netbox/netbox/views/generic/bulk_views.py

@@ -1,5 +1,6 @@
 import logging
 import re
+from collections import Counter
 from copy import deepcopy
 
 from django.contrib import messages
@@ -33,6 +34,7 @@ from utilities.jobs import is_background_request, process_request_as_job
 from utilities.permissions import get_permission_for_model
 from utilities.query import reapply_model_ordering
 from utilities.request import safe_for_redirect
+from utilities.string import title
 from utilities.tables import get_table_configs
 from utilities.views import GetReturnURLMixin, get_action_url
 from .base import BaseMultiObjectView
@@ -443,6 +445,18 @@ class BulkImportView(GetReturnURLMixin, BaseMultiObjectView):
 
         # Prefetch objects to be updated, if any
         prefetch_ids = [int(record['id']) for record in records if record.get('id')]
+
+        # check for duplicate IDs
+        duplicate_pks = [pk for pk, count in Counter(prefetch_ids).items() if count > 1]
+        if duplicate_pks:
+            error_msg = _(
+                "Duplicate objects found: {model} with ID(s) {ids} appears multiple times"
+            ).format(
+                model=title(self.queryset.model._meta.verbose_name),
+                ids=', '.join(str(pk) for pk in sorted(duplicate_pks))
+            )
+            raise ValidationError(error_msg)
+
         prefetched_objects = {
             obj.pk: obj
             for obj in self.queryset.model.objects.filter(id__in=prefetch_ids)