1.4.30

Released: January 19, 2022

orm

• [orm] [bug] Fixed issue in joined-inheritance load of additional attributes functionality in deep multi-level inheritance where an intermediary table that contained no columns would not be included in the tables joined, instead linking those tables to their primary key identifiers. While this works fine, it nonetheless in 1.4 began producing the cartesian product compiler warning. The logic has been changed so that these intermediary tables are included regardless. While this does include additional tables in the query that are not technically necessary, this only occurs for the highly unusual case of deep 3+ level inheritance with intermediary tables that have no non primary key columns, potential performance impact is therefore expected to be negligible.

  References: #7507

• [orm] [bug] Fixed issue where calling upon _orm.registry.map_imperatively() more than once for the same class would produce an unexpected error, rather than an informative error that the target class is already mapped. This behavior differed from that of the _orm.mapper() function which does report an informative message already.

  References: #7579

• [orm] [bug] [asyncio] Added missing method _asyncio.AsyncSession.invalidate() to the _asyncio.AsyncSession class.

  References: #7524

• [orm] [bug] [regression] Fixed regression which appeared in 1.4.23 which could cause loader options to be mis-handled in some cases, in particular when using joined table inheritance in combination with the polymorphic_load="selectin" option as well as relationship lazy loading, leading to a TypeError.

  References: #7557

• [orm] [bug] [regression] Fixed ORM regression where calling the _orm.aliased() function against an existing _orm.aliased() construct would fail to produce correct SQL if the existing construct were against a fixed table. The fix allows that the original _orm.aliased() construct is disregarded if it were only against a table that's now being replaced. It also allows for correct behavior when constructing a _orm.aliased() without a selectable argument against a _orm.aliased() that's against a subuquery, to create an alias of that subquery (i.e. to change its name).

  The nesting behavior of _orm.aliased() remains in place for the case where the outer _orm.aliased() object is against a subquery which in turn refers to the inner _orm.aliased() object. This is a relatively new 1.4 feature that helps to suit use cases that were previously served by the deprecated Query.from_self() method.

  References: #7576

• [orm] [bug] Fixed issue where _sql.Select.correlate_except() method, when passed either the None value or no arguments, would not correlate any elements when used in an ORM context (that is, passing ORM entities as FROM clauses), rather than causing all FROM elements to be considered as "correlated" in the same way which occurs when using Core-only constructs.

  References: #7514

• [orm] [bug] [regression] Fixed regression from 1.3 where the "subqueryload" loader strategy would fail with a stack trace if used against a query that made use of _orm.Query.from_statement() or _sql.Select.from_statement(). As subqueryload requires modifying the original statement, it's not compatible with the "from_statement" use case, especially for statements made against the _sql.text() construct. The behavior now is equivalent to that of 1.3 and previously, which is that the loader strategy silently degrades to not be used for such statements, typically falling back to using the lazyload strategy.

  References: #7505

sql

• [sql] [bug] [postgresql] Added additional rule to the system that determines TypeEngine implementations from Python literals to apply a second level of adjustment to the type, so that a Python datetime with or without tzinfo can set the timezone=True parameter on the returned DateTime object, as well as Time. This helps with some round-trip scenarios on type-sensitive PostgreSQL dialects such as asyncpg, psycopg3 (2.0 only).

  References: #7537

• [sql] [bug] Added an informative error message when a method object is passed to a SQL construct. Previously, when such a callable were passed, as is a common typographical error when dealing with method-chained SQL constructs, they were interpreted as "lambda SQL" targets to be invoked at compilation time, which would lead to silent failures. As this feature was not intended to be used with methods, method objects are now rejected.

  References: #7032

mypy

• [mypy] [bug] Fixed Mypy crash when running id daemon mode caused by a missing attribute on an internal mypy Var instance.

  References: #7321

asyncio

• [asyncio] [usecase] Added new method AdaptedConnection.run_async() to the DBAPI connection interface used by asyncio drivers, which allows methods to be called against the underlying "driver" connection directly within a sync-style function where the await keyword can't be used, such as within SQLAlchemy event handler functions. The method is analogous to the _asyncio.AsyncConnection.run_sync() method which translates async-style calls to sync-style. The method is useful for things like connection-pool on-connect handlers that need to invoke awaitable methods on the driver connection when it's first created.

  References: #7580

postgresql

• [postgresql] [usecase] Added string rendering to the postgresql.UUID datatype, so that stringifying a statement with "literal_binds" that uses this type will render an appropriate string value for the PostgreSQL backend. Pull request courtesy José Duarte.

  References: #7561

• [postgresql] [bug] [asyncpg] Improved support for asyncpg handling of TIME WITH TIMEZONE, which was not fully implemented.

  References: #7537

• [postgresql] [bug] [mssql] [reflection] Fixed reflection of covering indexes to report include_columns as part of the dialect_options entry in the reflected index dictionary, thereby enabling round trips from reflection->create to be complete. Included columns continue to also be present under the include_columns key for backwards compatibility.

  References: #7382

• [postgresql] [bug] Fixed handling of array of enum values which require escape characters.

  References: #7418

mysql

• [mysql] [change] Replace SHOW VARIABLES LIKE statement with equivalent SELECT @@variable in MySQL and MariaDB dialect initialization. This should avoid mutex contention caused by SHOW VARIABLES, improving initialization performance.

  References: #7518

• [mysql] [bug] Removed unnecessary dependency on PyMySQL from the asyncmy dialect. Pull request courtesy long2ice.

  References: #7567