deprecate exception classes in Cursor attributes

src/MySQLdb/connections.py

@@ -4,6 +4,7 @@
 want to make your own subclasses. In most cases, you will probably
 override Connection.default_cursor with a non-standard Cursor class.
 """
+
 import re
 
 from . import cursors, _mysql
@@ -143,11 +144,11 @@ class object, used to create cursors (keyword only)
 
         :param bool local_infile:
             sets ``MYSQL_OPT_LOCAL_INFILE`` in ``mysql_options()`` enabling LOAD LOCAL INFILE from any path; zero disables;
-            
+
         :param str local_infile_dir:
-            sets ``MYSQL_OPT_LOAD_DATA_LOCAL_DIR`` in ``mysql_options()`` enabling LOAD LOCAL INFILE from any path; 
+            sets ``MYSQL_OPT_LOAD_DATA_LOCAL_DIR`` in ``mysql_options()`` enabling LOAD LOCAL INFILE from any path;
             if ``local_infile`` is set to ``True`` then this is ignored;
-            
+
             supported for mysql version >= 8.0.21
 
         :param bool autocommit:
@@ -244,8 +245,16 @@ class object, used to create cursors (keyword only)
                 self.autocommit(autocommit)
         self.messages = []
 
-    def _set_attributes(self, host=None, user=None, password=None, database="", port=3306,
-                        unix_socket=None, **kwargs):
+    def _set_attributes(
+        self,
+        host=None,
+        user=None,
+        password=None,
+        database="",
+        port=3306,
+        unix_socket=None,
+        **kwargs,
+    ):
         """set some attributes for otel"""
         if unix_socket and not host:
             host = "localhost"

src/MySQLdb/converters.py

@@ -30,6 +30,7 @@
 (with the copy() method), modify the copies, and then pass them to
 MySQL.connect().
 """
+
 from decimal import Decimal
 
 from MySQLdb._mysql import string_literal

src/MySQLdb/cursors.py

@@ -3,6 +3,7 @@
 This module implements Cursors of various types for MySQLdb. By
 default, MySQLdb uses the Cursor class.
 """
+
 import re
 
 from ._exceptions import ProgrammingError
@@ -46,20 +47,6 @@ class BaseCursor:
     #: Default value of max_allowed_packet is 1048576.
     max_stmt_length = 64 * 1024
 
-    from ._exceptions import (
-        MySQLError,
-        Warning,
-        Error,
-        InterfaceError,
-        DatabaseError,
-        DataError,
-        OperationalError,
-        IntegrityError,
-        InternalError,
-        ProgrammingError,
-        NotSupportedError,
-    )
-
     connection = None
 
     def __init__(self, connection):
@@ -344,16 +331,32 @@ def _fetch_row(self, size=1):
     def __iter__(self):
         return iter(self.fetchone, None)
 
-    Warning = Warning
-    Error = Error
-    InterfaceError = InterfaceError
-    DatabaseError = DatabaseError
-    DataError = DataError
-    OperationalError = OperationalError
-    IntegrityError = IntegrityError
-    InternalError = InternalError
-    ProgrammingError = ProgrammingError
-    NotSupportedError = NotSupportedError
+    def __getattr__(self, name):
+        # DB-API 2.0 optional extension says these errors can be accessed
+        # via Connection object. But MySQLdb had defined them on Cursor object.
+        import warnings
+        from . import _exceptions as err
+
+        if name in (
+            "Warning",
+            "Error",
+            "InterfaceError",
+            "DatabaseError",
+            "DataError",
+            "OperationalError",
+            "IntegrityError",
+            "InternalError",
+            "ProgrammingError",
+            "NotSupportedError",
+        ):
+            # Deprecated since v2.3. Will be removed in 2027.
+            warnings.warn(
+                "errors should be accessed from `MySQLdb` package",
+                DeprecationWarning,
+                stacklevel=2,
+            )
+            return getattr(err, name)
+        raise AttributeError(name)
 
 
 class CursorStoreResultMixIn:
@@ -423,7 +426,6 @@ def __iter__(self):
 
 
 class CursorUseResultMixIn:
-
     """This is a MixIn class which causes the result set to be stored
     in the server and sent row-by-row to client side, i.e. it uses
     mysql_use_result(). You MUST retrieve the entire result set and

src/MySQLdb/times.py

@@ -4,6 +4,7 @@
 
 Use Python datetime module to handle date and time columns.
 """
+
 from time import localtime
 from datetime import date, datetime, time, timedelta
 from MySQLdb._mysql import string_literal

tests/capabilities.py

@@ -1,10 +1,11 @@
 #!/usr/bin/env python -O
-""" Script to test database capabilities and the DB-API interface
-    for functionality and memory leaks.
+"""Script to test database capabilities and the DB-API interface
+for functionality and memory leaks.
 
-    Adapted from a script by M-A Lemburg.
+Adapted from a script by M-A Lemburg.
 
 """
+
 from time import time
 import unittest
 from configdb import connection_factory

tests/dbapi20.py

@@ -1,14 +1,14 @@
 #!/usr/bin/env python
-""" Python DB API 2.0 driver compliance unit test suite.
+"""Python DB API 2.0 driver compliance unit test suite.
 
-    This software is Public Domain and may be used without restrictions.
+   This software is Public Domain and may be used without restrictions.
 
- "Now we have booze and barflies entering the discussion, plus rumours of
-  DBAs on drugs... and I won't tell you what flashes through my mind each
-  time I read the subject line with 'Anal Compliance' in it.  All around
-  this is turning out to be a thoroughly unwholesome unit test."
+"Now we have booze and barflies entering the discussion, plus rumours of
+ DBAs on drugs... and I won't tell you what flashes through my mind each
+ time I read the subject line with 'Anal Compliance' in it.  All around
+ this is turning out to be a thoroughly unwholesome unit test."
 
-    -- Ian Bicking
+   -- Ian Bicking
 """
 
 __rcs_id__ = "$Id$"
@@ -300,7 +300,7 @@ def test_rowcount(self):
             self.assertEqual(
                 cur.rowcount,
                 -1,
-                "cursor.rowcount should be -1 after executing no-result " "statements",
+                "cursor.rowcount should be -1 after executing no-result statements",
             )
             cur.execute(
                 "insert into %sbooze values ('Victoria Bitter')" % (self.table_prefix)
@@ -410,12 +410,12 @@ def _paraminsert(self, cur):
         self.assertEqual(
             beers[0],
             "Cooper's",
-            "cursor.fetchall retrieved incorrect data, or data inserted " "incorrectly",
+            "cursor.fetchall retrieved incorrect data, or data inserted incorrectly",
         )
         self.assertEqual(
             beers[1],
             "Victoria Bitter",
-            "cursor.fetchall retrieved incorrect data, or data inserted " "incorrectly",
+            "cursor.fetchall retrieved incorrect data, or data inserted incorrectly",
         )
 
     def test_executemany(self):
@@ -483,7 +483,7 @@ def test_fetchone(self):
             self.assertEqual(
                 cur.fetchone(),
                 None,
-                "cursor.fetchone should return None if a query retrieves " "no rows",
+                "cursor.fetchone should return None if a query retrieves no rows",
             )
             self.assertTrue(cur.rowcount in (-1, 0))
 

tests/test_MySQLdb_dbapi20.py

@@ -98,7 +98,7 @@ def test_fetchone(self):
             self.assertEqual(
                 cur.fetchone(),
                 None,
-                "cursor.fetchone should return None if a query retrieves " "no rows",
+                "cursor.fetchone should return None if a query retrieves no rows",
             )
             self.assertTrue(cur.rowcount in (-1, 0))
 
@@ -172,9 +172,7 @@ def help_nextset_setUp(self, cur):
                select count(*) from %(tp)sbooze;
                select name from %(tp)sbooze;
            end
-        """ % dict(
-            tp=self.table_prefix
-        )
+        """ % dict(tp=self.table_prefix)
         cur.execute(sql)
 
     def help_nextset_tearDown(self, cur):

tests/test_cursor.py

@@ -57,9 +57,9 @@ def test_executemany():
         "INSERT INTO TEST (ID, NAME) VALUES (%(id_name)s, %(name)s) ON duplicate update"
     )
     assert m is not None, "error parse %(id_name)s"
-    assert (
-        m.group(3) == " ON duplicate update"
-    ), "group 3 not ON duplicate update, bug in RE_INSERT_VALUES?"
+    assert m.group(3) == " ON duplicate update", (
+        "group 3 not ON duplicate update, bug in RE_INSERT_VALUES?"
+    )
 
     # https://github.com/PyMySQL/mysqlclient-python/issues/178
     m = MySQLdb.cursors.RE_INSERT_VALUES.match(
@@ -75,16 +75,16 @@ def test_executemany():
     # list args
     data = [(i,) for i in range(10)]
     cursor.executemany("insert into test (data) values (%s)", data)
-    assert cursor._executed.endswith(
-        b",(7),(8),(9)"
-    ), "execute many with %s not in one query"
+    assert cursor._executed.endswith(b",(7),(8),(9)"), (
+        "execute many with %s not in one query"
+    )
 
     # dict args
     data_dict = [{"data": i} for i in range(10)]
     cursor.executemany("insert into test (data) values (%(data)s)", data_dict)
-    assert cursor._executed.endswith(
-        b",(7),(8),(9)"
-    ), "execute many with %(data)s not in one query"
+    assert cursor._executed.endswith(b",(7),(8),(9)"), (
+        "execute many with %(data)s not in one query"
+    )
 
     # %% in column set
     cursor.execute(
@@ -97,9 +97,9 @@ def test_executemany():
         q = "INSERT INTO percent_test (`A%%`, `B%%`) VALUES (%s, %s)"
         assert MySQLdb.cursors.RE_INSERT_VALUES.match(q) is not None
         cursor.executemany(q, [(3, 4), (5, 6)])
-        assert cursor._executed.endswith(
-            b"(3, 4),(5, 6)"
-        ), "executemany with %% not in one query"
+        assert cursor._executed.endswith(b"(3, 4),(5, 6)"), (
+            "executemany with %% not in one query"
+        )
     finally:
         cursor.execute("DROP TABLE IF EXISTS percent_test")