Prevent signal handlers from indexing the content of fields omitted from save(update_fields=[...]).

Fixes #3239

wagtail/wagtailsearch/signal_handlers.py

@@ -5,7 +5,13 @@ from django.db.models.signals import post_delete, post_save
 from wagtail.wagtailsearch import index
 
 
-def post_save_signal_handler(instance, **kwargs):
+def post_save_signal_handler(instance, update_fields=None, **kwargs):
+    if update_fields is not None:
+        # fetch a fresh copy of instance from the database to ensure
+        # that we're not indexing any of the unsaved data contained in
+        # the fields that were not passed in update_fields
+        instance = type(instance).objects.get(pk=instance.pk)
+
     index.insert_or_update_object(instance)
 
 

wagtail/wagtailsearch/tests/test_index_functions.py

@@ -166,3 +166,16 @@ class TestSignalHandlers(TestCase, WagtailTestUtils):
         backend().reset_mock()
         obj.delete()
         backend().delete.assert_called_with(obj)
+
+    def test_do_not_index_fields_omitted_from_update_fields(self, backend):
+        obj = models.SearchTest.objects.create(title="Test", content="This is the original content")
+
+        backend().reset_mock()
+        obj.title = "Updated test"
+        obj.content = "This is the updated content"
+        obj.save(update_fields=['title'])
+
+        backend().add.assert_called_once()
+        indexed_object = backend().add.call_args[0][0]
+        self.assertEqual(indexed_object.title, "Updated test")
+        self.assertEqual(indexed_object.content, "This is the original content")