gh-101698: Deprecate using named placeholders with sequences

erlend-aasland · erlend-aasland · commit b6938950f099 · 2023-02-08T18:49:14.000+01:00
diff --git a/Doc/whatsnew/3.12.rst b/Doc/whatsnew/3.12.rst
@@ -415,6 +415,13 @@ Deprecated
   and tailor them to your needs.
   (Contributed by Erlend E. Aasland in :gh:`90016`.)
 
+* In :meth:`~sqlite3.Cursor.execute`, :exc:`DeprecationWarning` is now raised
+  when :ref:`named placeholders <sqlite3-placeholders>` are used together with
+  parameters supplied as a :term:`sequence`.
+  Starting from Python 3.14, using named placeholders with parameters supplied
+  as a sequence will raise a :exc:`~sqlite3.ProgrammingError`.
+  (Contributed by Erlend E. Aasland in :gh:`101698`.)
+
 * The 3-arg signatures (type, value, traceback) of :meth:`~coroutine.throw`,
   :meth:`~generator.throw` and :meth:`~agen.athrow` are deprecated and
   may be removed in a future version of Python. Use the single-arg versions
diff --git a/Lib/test/test_sqlite3/test_dbapi.py b/Lib/test/test_sqlite3/test_dbapi.py
@@ -861,6 +861,20 @@ def __getitem__(slf, x):
         with self.assertRaises(ZeroDivisionError):
             self.cu.execute("select name from test where name=?", L())
 
+    def test_execute_named_param_and_sequence(self):
+        dataset = (
+            ("select :a", (1,)),
+            ("select :a, ?, ?", (1, 2, 3)),
+            ("select ?, :b, ?", (1, 2, 3)),
+            ("select ?, ?, :c", (1, 2, 3)),
+        )
+        msg = "Binding.*is a named parameter"
+        for query, params in dataset:
+            with self.subTest(query=query, params=params):
+                with self.assertWarnsRegex(DeprecationWarning, msg) as cm:
+                    self.cu.execute(query, params)
+                self.assertEqual(cm.filename,  __file__)
+
     def test_execute_too_many_params(self):
         category = sqlite.SQLITE_LIMIT_VARIABLE_NUMBER
         msg = "too many SQL variables"
diff --git a/Misc/NEWS.d/next/Library/2023-02-08-18-20-58.gh-issue-101693.4_LPXj.rst b/Misc/NEWS.d/next/Library/2023-02-08-18-20-58.gh-issue-101693.4_LPXj.rst
@@ -0,0 +1,6 @@
+In :meth:`sqlite3.Cursor.execute`, :exc:`DeprecationWarning` is now raised
+when :ref:`named placeholders <sqlite3-placeholders>` are used together with
+parameters supplied as a :term:`sequence`.
+Starting from Python 3.14, using named placeholders with parameters supplied
+as a sequence will raise a :exc:`~sqlite3.ProgrammingError`.
+Patch by Erlend E. Aasland.
diff --git a/Modules/_sqlite/cursor.c b/Modules/_sqlite/cursor.c
@@ -662,6 +662,17 @@ bind_parameters(pysqlite_state *state, pysqlite_Statement *self,
             return;
         }
         for (i = 0; i < num_params; i++) {
+            const char *name = sqlite3_bind_parameter_name(self->st, i+1);
+            if (name != NULL) {
+                PyErr_WarnFormat(PyExc_DeprecationWarning, 1,
+                                 "Binding %d ('%s') is a named parameter, "
+                                 "but you supplied a sequence which requires "
+                                 "nameless (qmark) placeholders. "
+                                 "Starting with Python 3.14 an "
+                                 "sqlite3.ProgrammingError will be raised.",
+                                 i+1, name);
+            }
+
             if (PyTuple_CheckExact(parameters)) {
                 PyObject *item = PyTuple_GET_ITEM(parameters, i);
                 current_param = Py_NewRef(item);
