2.0.24

Released: December 28, 2023

orm

• [orm] [bug] Improved a fix first implemented for #3208 released in version 0.9.8, where the registry of classes used internally by declarative could be subject to a race condition in the case where individual mapped classes are being garbage collected at the same time while new mapped classes are being constructed, as can happen in some test suite configurations or dynamic class creation environments. In addition to the weakref check already added, the list of items being iterated is also copied first to avoid "list changed while iterating" errors. Pull request courtesy Yilei Yang.

  This change is also backported to: 1.4.51

  References: #10782

• [orm] [bug] Fixed issue where use of _orm.foreign() annotation on a non-initialized _orm.mapped_column() construct would produce an expression without a type, which was then not updated at initialization time of the actual column, leading to issues such as relationships not determining use_get appropriately.

  References: #10597

• [orm] [bug] Improved the error message produced when the unit of work process sets the value of a primary key column to NULL due to a related object with a dependency rule on that column being deleted, to include not just the destination object and column name but also the source column from which the NULL value is originating. Pull request courtesy Jan Vollmer.

  References: #10668

• [orm] [bug] Modified the __init_subclass__() method used by _orm.MappedAsDataclass, _orm.DeclarativeBase and _orm.DeclarativeBaseNoMeta to accept arbitrary **kw and to propagate them to the super() call, allowing greater flexibility in arranging custom superclasses and mixins which make use of __init_subclass__() keyword arguments. Pull request courtesy Michael Oliver.

  References: #10732

• [orm] [bug] Ensured the use case of Bundle objects used in the returning() portion of ORM-enabled INSERT, UPDATE and DELETE statements is tested and works fully. This was never explicitly implemented or tested previously and did not work correctly in the 1.4 series; in the 2.0 series, ORM UPDATE/DELETE with WHERE criteria was missing an implementation method preventing Bundle objects from working.

  References: #10776

• [orm] [bug] Fixed 2.0 regression in MutableList where a routine that detects sequences would not correctly filter out string or bytes instances, making it impossible to assign a string value to a specific index (while non-sequence values would work fine).

  References: #10784

engine

• [engine] [bug] Fixed URL-encoding of the username and password components of engine.URL objects when converting them to string using the _engine.URL.render_as_string() method, by using Python standard library urllib.parse.quote while allowing for plus signs and spaces to remain unchanged as supported by SQLAlchemy's non-standard URL parsing, rather than the legacy home-grown routine from many years ago. Pull request courtesy of Xavier NUNN.

  References: #10662

sql

• [sql] [bug] Fixed issue in stringify for SQL elements, where a specific dialect is not passed, where a dialect-specific element such as the PostgreSQL "on conflict do update" construct is encountered and then fails to provide for a stringify dialect with the appropriate state to render the construct, leading to internal errors.

  References: #10753

• [sql] [bug] Fixed issue where stringifying or compiling a CTE that was against a DML construct such as an _sql.insert() construct would fail to stringify, due to a mis-detection that the statement overall is an INSERT, leading to internal errors.

schema

• [schema] [bug] Fixed issue where error reporting for unexpected schema item when creating objects like _schema.Table would incorrectly handle an argument that was itself passed as a tuple, leading to a formatting error. The error message has been modernized to use f-strings.

  References: #10654

typing

• [typing] [bug] Completed pep-484 typing for the sqlalchemy.sql.functions module. _sql.select() constructs made against func elements should now have filled-in return types.

  References: #6810

asyncio

• [asyncio] [change] The async_fallback dialect argument is now deprecated, and will be removed in SQLAlchemy 2.1. This flag has not been used for SQLAlchemy's test suite for some time. asyncio dialects can still run in a synchronous style by running code within a greenlet using _util.greenlet_spawn().

postgresql

• [postgresql] [bug] Adjusted the asyncpg dialect such that when the terminate() method is used to discard an invalidated connection, the dialect will first attempt to gracefully close the connection using .close() with a timeout, if the operation is proceeding within an async event loop context only. This allows the asyncpg driver to attend to finalizing a TimeoutError including being able to close a long-running query server side, which otherwise can keep running after the program has exited.

  References: #10717

mysql

• [mysql] [bug] Fixed regression introduced by the fix in ticket #10492 when using pool pre-ping with PyMySQL version older than 1.0.

  This change is also backported to: 1.4.51

  References: #10650

• [mysql] [bug] Fixed regression introduced by the fix in ticket #10492 when using pool pre-ping with PyMySQL version older than 1.0.

  This change is also backported to: 1.4.51

  References: #10650

tests

• [tests] [bug] Improvements to the test suite to further harden its ability to run when Python greenlet is not installed. There is now a tox target that includes the token "nogreenlet" that will run the suite with greenlet not installed (note that it still temporarily installs greenlet as part of the tox config, however).

  References: #10747