:released: February 6, 2023
.. change::
:tags: bug, orm declarative
:tickets: 9249
Fixed regression caused by the fix for :ticket:`9171`, which itself was
fixing a regression, involving the mechanics of ``__init__()`` on classes
that extend from :class:`_orm.DeclarativeBase`. The change made it such
that ``__init__()`` was applied to the user-defined base if there were no
``__init__()`` method directly on the class. This has been adjusted so that
``__init__()`` is applied only if no other class in the hierarchy of the
user-defined base has an ``__init__()`` method. This again allows
user-defined base classes based on :class:`_orm.DeclarativeBase` to include
mixins that themselves include a custom ``__init__()`` method.
.. change::
:tags: bug, mysql, regression
:tickets: 9251
Fixed regression caused by issue :ticket:`9058` which adjusted the MySQL
dialect's ``has_table()`` to again use "DESCRIBE", where the specific error
code raised by MySQL version 8 when using a non-existent schema name was
unexpected and failed to be interpreted as a boolean result.
.. change::
:tags: bug, sqlite
:tickets: 9251
Fixed the SQLite dialect's ``has_table()`` function to correctly report
False for queries that include a non-None schema name for a schema that
doesn't exist; previously, a database error was raised.
.. change::
:tags: bug, orm declarative
:tickets: 9226
Fixed issue in ORM Declarative Dataclass mappings related to newly added
support for mixins added in 2.0.1 via :ticket:`9179`, where a combination
of using mixins plus ORM inheritance would mis-classify fields in some
cases leading to field-level dataclass arguments such as ``init=False`` being
lost.
.. change::
:tags: bug, orm, ression
:tickets: 9232
Fixed obscure ORM inheritance issue caused by :ticket:`8705` where some
scenarios of inheriting mappers that indicated groups of columns from the
local table and the inheriting table together under a
:func:`_orm.column_property` would nonetheless warn that properties of the
same name were being combined implicitly.
.. change::
:tags: orm, bug, regression
:tickets: 9228
Fixed regression where using the :paramref:`_orm.Mapper.version_id_col`
feature with a regular Python-side incrementing column would fail to work
for SQLite and other databases that don't support "rowcount" with
"RETURNING", as "RETURNING" would be assumed for such columns even though
that's not what actually takes place.
.. change::
:tags: bug, orm declarative
:tickets: 9240
Repaired ORM Declarative mappings to allow for the
:paramref:`_orm.Mapper.primary_key` parameter to be specified within
``__mapper_args__`` when using :func:`_orm.mapped_column`. Despite this
usage being directly in the 2.0 documentation, the :class:`_orm.Mapper` was
not accepting the :func:`_orm.mapped_column` construct in this context. Ths
feature was already working for the :paramref:`_orm.Mapper.version_id_col`
and :paramref:`_orm.Mapper.polymorphic_on` parameters.
As part of this change, the ``__mapper_args__`` attribute may be specified
without using :func:`_orm.declared_attr` on a non-mapped mixin class,
including a ``"primary_key"`` entry that refers to :class:`_schema.Column`
or :func:`_orm.mapped_column` objects locally present on the mixin;
Declarative will also translate these columns into the correct ones for a
particular mapped class. This again was working already for the
:paramref:`_orm.Mapper.version_id_col` and
:paramref:`_orm.Mapper.polymorphic_on` parameters. Additionally,
elements within ``"primary_key"`` may be indicated as string names of
existing mapped properties.
.. change::
:tags: usecase, sql
:tickets: 8780
Added a full suite of new SQL bitwise operators, for performing
database-side bitwise expressions on appropriate data values such as
integers, bit-strings, and similar. Pull request courtesy Yegor Statkevich.
.. seealso::
:ref:`operators_bitwise`
.. change::
:tags: bug, orm declarative
:tickets: 9211
An explicit error is raised if a mapping attempts to mix the use of
:class:`_orm.MappedAsDataclass` with
:meth:`_orm.registry.mapped_as_dataclass` within the same class hierarchy,
as this produces issues with the dataclass function being applied at the
wrong time to the mapped class, leading to errors during the mapping
process.
.. change::
:tags: bug, orm, regression
:tickets: 9217
Fixed regression when using :meth:`_sql.Select.from_statement` in an ORM
context, where matching of columns to SQL labels based on name alone was
disabled for ORM-statements that weren't fully textual. This would prevent
arbitrary SQL expressions with column-name labels from matching up to the
entity to be loaded, which previously would work within the 1.4
and previous series, so the previous behavior has been restored.
.. change::
:tags: bug, asyncio
:tickets: 9237
Repaired a regression caused by the fix for :ticket:`8419` which caused
asyncpg connections to be reset (i.e. transaction ``rollback()`` called)
and returned to the pool normally in the case that the connection were not
explicitly returned to the connection pool and was instead being
intercepted by Python garbage collection, which would fail if the garbage
collection operation were being called outside of the asyncio event loop,
leading to a large amount of stack trace activity dumped into logging
and standard output.
The correct behavior is restored, which is that all asyncio connections
that are garbage collected due to not being explicitly returned to the
connection pool are detached from the pool and discarded, along with a
warning, rather than being returned the pool, as they cannot be reliably
reset. In the case of asyncpg connections, the asyncpg-specific
``terminate()`` method will be used to end the connection more gracefully
within this process as opposed to just dropping it.
This change includes a small behavioral change that is hoped to be useful
for debugging asyncio applications, where the warning that's emitted in the
case of asyncio connections being unexpectedly garbage collected has been
made slightly more aggressive by moving it outside of a ``try/except``
block and into a ``finally:`` block, where it will emit unconditionally
regardless of whether the detach/termination operation succeeded or not. It
will also have the effect that applications or test suites which promote
Python warnings to exceptions will see this as a full exception raise,
whereas previously it was not possible for this warning to actually
propagate as an exception. Applications and test suites which need to
tolerate this warning in the interim should adjust the Python warnings
filter to allow these warnings to not raise.
The behavior for traditional sync connections remains unchanged, that
garbage collected connections continue to be returned to the pool normally
without emitting a warning. This will likely be changed in a future major
release to at least emit a similar warning as is emitted for asyncio
drivers, as it is a usage error for pooled connections to be intercepted by
garbage collection without being properly returned to the pool.
.. change::
:tags: usecase, orm
:tickets: 9220
Added new event hook :meth:`_orm.MapperEvents.after_mapper_constructed`,
which supplies an event hook to take place right as the
:class:`_orm.Mapper` object has been fully constructed, but before the
:meth:`_orm.registry.configure` call has been called. This allows code that
can create additional mappings and table structures based on the initial
configuration of a :class:`_orm.Mapper`, which also integrates within
Declarative configuration. Previously, when using Declarative, where the
:class:`_orm.Mapper` object is created within the class creation process,
there was no documented means of running code at this point. The change
is to immediately benefit custom mapping schemes such as that
of the :ref:`examples_versioned_history` example, which generate additional
mappers and tables in response to the creation of mapped classes.
.. change::
:tags: usecase, orm
:tickets: 9220
The infrequently used :attr:`_orm.Mapper.iterate_properties` attribute and
:meth:`_orm.Mapper.get_property` method, which are primarily used
internally, no longer implicitly invoke the :meth:`_orm.registry.configure`
process. Public access to these methods is extremely rare and the only
benefit to having :meth:`_orm.registry.configure` would have been allowing
"backref" properties be present in these collections. In order to support
the new :meth:`_orm.MapperEvents.after_mapper_constructed` event, iteration
and access to the internal :class:`_orm.MapperProperty` objects is now
possible without triggering an implicit configure of the mapper itself.
The more-public facing route to iteration of all mapper attributes, the
:attr:`_orm.Mapper.attrs` collection and similar, will still implicitly
invoke the :meth:`_orm.registry.configure` step thus making backref
attributes available.
In all cases, the :meth:`_orm.registry.configure` is always available to
be called directly.
.. change::
:tags: bug, examples
:tickets: 9220
Reworked the :ref:`examples_versioned_history` to work with
version 2.0, while at the same time improving the overall working of
this example to use newer APIs, including a newly added hook
:meth:`_orm.MapperEvents.after_mapper_constructed`.
.. change::
:tags: bug, mysql
:tickets: 8626
Added support for MySQL 8's new ``AS <name> ON DUPLICATE KEY`` syntax when
using :meth:`_mysql.Insert.on_duplicate_key_update`, which is required for
newer versions of MySQL 8 as the previous syntax using ``VALUES()`` now
emits a deprecation warning with those versions. Server version detection
is employed to determine if traditional MariaDB / MySQL < 8 ``VALUES()``
syntax should be used, vs. the newer MySQL 8 required syntax. Pull request
courtesy Caspar Wylie.
.. changelog::