pythongh-118221: Always use the default row factory in sqlite3.iterdump()

The iterdump() implementation depends on the row factory returning
resulting rows as tuples; it will fail with custom row factories like
for example a dict factory.

Fixed by overriding the row factory of the cursor used by iterdump().
FTR, this does not affect the row factory of the parent connection.

Author: erlend-aasland

Lib/sqlite3/dump.py

@@ -26,6 +26,7 @@ def _iterdump(connection, *, filter=None):
 
     writeable_schema = False
     cu = connection.cursor()
+    cu.row_factory = None  # Make sure we get predictable results.
     # Disable foreign key constraints, if there is any foreign key violation.
     violations = cu.execute("PRAGMA foreign_key_check").fetchall()
     if violations:

Lib/test/test_sqlite3/test_dump.py

@@ -190,6 +190,21 @@ def __getitem__(self, index):
         got = list(self.cx.iterdump())
         self.assertEqual(expected, got)
 
+    def test_dump_custom_row_factory(self):
+        # gh-118221: iterdump should be able to cope with custom row factories
+        def dict_factory(cu, row):
+            fields = [col[0] for col in cu.description]
+            return {k: v for k, v in zip(fields, row)}
+
+        self.cx.row_factory = dict_factory
+        CREATE_TABLE = "CREATE TABLE test(t);"
+        expected = ["BEGIN TRANSACTION;", CREATE_TABLE, "COMMIT;"]
+
+        self.cu.execute(CREATE_TABLE)
+        actual = list(self.cx.iterdump())
+        self.assertEqual(expected, actual)
+        self.assertEqual(self.cx.row_factory, dict_factory)
+
     def test_dump_virtual_tables(self):
         # gh-64662
         expected = [

Misc/NEWS.d/next/Library/2024-04-24-12-29-33.gh-issue-118221.2k_bac.rst

@@ -0,0 +1,2 @@
+Fix a bug where :func:`sqlite3.iterdump` could fail if a custom :attr:`row
+factory <sqlite3.Cursor.row_factory>` was supplied. Patch by Erlend Aasland.