Fix dropping a non existing atlas index

Author: WaVEV

django_mongodb_backend/schema.py

@@ -293,7 +293,13 @@ def remove_index(self, model, index):
         if index.contains_expressions:
             return
         if isinstance(index, SearchIndex | VectorSearchIndex):
-            if self.connection.features.supports_atlas_search:
+            # Drop the index if it exists, particularly if it may not have been created previously
+            # due to lack of Atlas search support, but now the database supports it.
+            constraints = self.connection.introspection.get_constraints(
+                cursor=None,
+                table_name=model._meta.db_table,
+            )
+            if self.connection.features.supports_atlas_search and index.name in constraints:
                 self.get_collection(model._meta.db_table).drop_search_index(index.name)
         else:
             self.get_collection(model._meta.db_table).drop_index(index.name)

tests/indexes_/test_atlas_indexes.py

@@ -1,3 +1,5 @@
+from unittest import mock
+
 from django.db import connection
 from django.test import TestCase, skipIfDBFeature, skipUnlessDBFeature
 
@@ -38,6 +40,17 @@ def test_simple(self):
             editor.add_index(index=index, model=Article)
             self.assertAddRemoveIndex(editor, Article, index)
 
+    def test_drop_non_existing_index(self):
+        with connection.schema_editor() as editor:
+            index = SearchIndex(
+                name="recent_article_idx",
+                fields=["number"],
+            )
+            editor.get_collection = mock.MagicMock()
+            editor.remove_index(index=index, model=Article)
+            # Verify that the collection was not accessed
+            editor.get_collection.assert_not_called()
+
     @skipIfDBFeature("supports_atlas_search")
     def test_index_not_created(self):
         with connection.schema_editor() as editor:
@@ -120,6 +133,17 @@ def assertAddRemoveIndex(self, editor, model, index):
             ),
         )
 
+    def test_drop_non_existing_index(self):
+        with connection.schema_editor() as editor:
+            index = SearchIndex(
+                name="recent_article_idx",
+                fields=["number"],
+            )
+            editor.get_collection = mock.MagicMock()
+            editor.remove_index(index=index, model=Article)
+            # Verify that the collection was not accessed
+            editor.get_collection.assert_not_called()
+
     @skipUnlessDBFeature("supports_atlas_search")
     def test_deconstruct_default_similarity(self):
         index = VectorSearchIndex(