gh-93421: Fix sqlite3 cursor .rowcount for UPDATE ... RETURNING queries

Lib/test/test_sqlite3/test_dbapi.py

@@ -887,6 +887,14 @@ def test_rowcount_executemany(self):
  self.cu.executemany("insert into test(name) values (?)", [(1,), (2,), (3,)])
  self.assertEqual(self.cu.rowcount, 3)
 
+ @unittest.skipIf(sqlite.sqlite_version_info < (3, 35, 0),
+ "Requires SQLite 3.35.0 or newer")
+ def test_rowcount_update_returning(self):
+ # gh-93421: rowcount is updated correctly for UPDATE...RETURNING queries
+ self.cu.execute("update test set name='bar' where name='foo' returning 1")
+ self.assertEqual(self.cu.fetchone()[0], 1)
+ self.assertEqual(self.cu.rowcount, 1)
+
  def test_total_changes(self):
  self.cu.execute("insert into test(name) values ('foo')")
  self.cu.execute("insert into test(name) values ('foo')")

Misc/NEWS.d/next/Library/2022-06-05-22-22-42.gh-issue-93421.43UO_8.rst

@@ -0,0 +1,2 @@
+Fix :data:`sqlite3.Cursor.rowcount` for ``UPDATE ... RETURNING``` SQL
+queries. Patch by Erlend E. Aasland.

Modules/_sqlite/cursor.c

@@ -776,6 +776,16 @@ stmt_mark_dirty(pysqlite_Statement *self)
  self->in_use = 1;
 }
 
+static inline sqlite3_int64
+total_changes(sqlite3 *db)
+{
+#if SQLITE_VERSION_NUMBER >= 3037000
+ return sqlite3_total_changes64(db);
+#else
+ return (sqlite3_int64)sqlite3_total_changes(db);
+#endif
+}
+
 PyObject *
 _pysqlite_query_execute(pysqlite_Cursor* self, int multiple, PyObject* operation, PyObject* second_argument)
 {
@@ -835,10 +845,9 @@ _pysqlite_query_execute(pysqlite_Cursor* self, int multiple, PyObject* operation
  stmt_reset(self->statement);
  }
 
- /* reset description and rowcount */
+ /* reset description */
  Py_INCREF(Py_None);
  Py_SETREF(self->description, Py_None);
- self->rowcount = 0L;
 
  if (self->statement){
  (void)stmt_reset(self->statement);
@@ -879,6 +888,14 @@ _pysqlite_query_execute(pysqlite_Cursor* self, int multiple, PyObject* operation
  }
  }
 
+ if (self->statement->is_dml){
+ // Save current row count
+ self->rowcount = total_changes(self->connection->db);
+ }
+ else{
+ self->rowcount = -1L;
+ }
+
  while (1){
  parameters = PyIter_Next(parameters_iter);
  if (!parameters){
@@ -944,12 +961,6 @@ _pysqlite_query_execute(pysqlite_Cursor* self, int multiple, PyObject* operation
  }
  }
 
- if (self->statement->is_dml){
- self->rowcount += (long)sqlite3_changes(self->connection->db);
- } else{
- self->rowcount= -1L;
- }
-
  if (rc == SQLITE_DONE && !multiple){
  stmt_reset(self->statement);
  Py_CLEAR(self->statement);
@@ -1308,6 +1319,19 @@ pysqlite_cursor_close_impl(pysqlite_Cursor *self)
  Py_RETURN_NONE;
 }
 
+static PyObject *
+get_rowcount(pysqlite_Cursor *self, void *Py_UNUSED(closure))
+{
+ if (!check_cursor(self)){
+ return NULL;
+ }
+ if (self->rowcount == -1L){
+ return PyLong_FromLong(-1L);
+ }
+ sqlite3_int64 changes = total_changes(self->connection->db);
+ return PyLong_FromLong(changes - self->rowcount);
+}
+
 static PyMethodDef cursor_methods[] ={
  PYSQLITE_CURSOR_CLOSE_METHODDEF
  PYSQLITE_CURSOR_EXECUTEMANY_METHODDEF
@@ -1327,12 +1351,16 @@ static struct PyMemberDef cursor_members[] =
 {"description", T_OBJECT, offsetof(pysqlite_Cursor, description), READONLY},
 {"arraysize", T_INT, offsetof(pysqlite_Cursor, arraysize), 0},
 {"lastrowid", T_OBJECT, offsetof(pysqlite_Cursor, lastrowid), READONLY},
-{"rowcount", T_LONG, offsetof(pysqlite_Cursor, rowcount), READONLY},
 {"row_factory", T_OBJECT, offsetof(pysqlite_Cursor, row_factory), 0},
 {"__weaklistoffset__", T_PYSSIZET, offsetof(pysqlite_Cursor, in_weakreflist), READONLY},
 {NULL}
 };
 
+static PyGetSetDef cursor_getset[] ={
+{"rowcount", (getter)get_rowcount, (setter)NULL},
+{NULL},
+};
+
 static const char cursor_doc[] =
 PyDoc_STR("SQLite database cursor class.");
 
@@ -1346,6 +1374,7 @@ static PyType_Slot cursor_slots[] ={
 {Py_tp_init, pysqlite_cursor_init},
 {Py_tp_traverse, cursor_traverse},
 {Py_tp_clear, cursor_clear},
+{Py_tp_getset, cursor_getset},
 {0, NULL},
 };
 

Modules/_sqlite/cursor.h

@@ -38,7 +38,7 @@ typedef struct
  PyObject* row_cast_map;
  int arraysize;
  PyObject* lastrowid;
-long rowcount;
+sqlite3_int64 rowcount; // Saved row count
  PyObject* row_factory;
  pysqlite_Statement* statement;
  int closed;