1.4.1

Released: March 17, 2021

orm

• [orm] [bug] [regression] Fixed regression where producing a Core expression construct such as
  _sql.select() using ORM entities would eagerly configure the mappers,
  in an effort to maintain compatibility with the _orm.Query object
  which necessarily does this to support many backref-related legacy cases.
  However, core _sql.select() constructs are also used in mapper
  configurations and such, and to that degree this eager configuration is
  more of an inconvenience, so eager configure has been disabled for the
  _sql.select() and other Core constructs in the absence of ORM loading
  types of functions such as _orm.Load.

  The change maintains the behavior of _orm.Query so that backwards
  compatibility is maintained. However, when using a _sql.select() in
  conjunction with ORM entities, a "backref" that isn't explicitly placed on
  one of the classes until mapper configure time won't be available unless
  _orm.configure_mappers() or the newer _orm.registry.configure()
  has been called elsewhere. Prefer using
  _orm.relationship.back_populates for more explicit relationship
  configuration which does not have the eager configure requirement.

  References: #6066

• [orm] [bug] [regression] Fixed a critical regression in the relationship lazy loader where the SQL
  criteria used to fetch a related many-to-one object could go stale in
  relation to other memoized structures within the loader if the mapper had
  configuration changes, such as can occur when mappers are late configured
  or configured on demand, producing a comparison to None and returning no
  object. Huge thanks to Alan Hamlett for their help tracking this down late
  into the night.

  References: #6055

• [orm] [bug] [regression] Fixed regression where the _orm.Query.exists() method would fail to
  create an expression if the entity list of the _orm.Query were
  an arbitrary SQL column expression.

  References: #6076

• [orm] [bug] [regression] Fixed regression where calling upon _orm.Query.count() in conjunction
  with a loader option such as _orm.joinedload() would fail to ignore
  the loader option. This is a behavior that has always been very specific to
  the _orm.Query.count() method; an error is normally raised if a given
  _orm.Query has options that don't apply to what it is returning.

  References: #6052

• [orm] [bug] [regression] Fixed regression in _orm.Session.identity_key(), including that the
  method and related methods were not covered by any unit test as well as
  that the method contained a typo preventing it from functioning correctly.

  References: #6067

orm declarative

• [orm] [declarative] [bug] [regression] Fixed bug where user-mapped classes that contained an attribute named
  "registry" would cause conflicts with the new registry-based mapping system
  when using DeclarativeMeta. While the attribute remains
  something that can be set explicitly on a declarative base to be
  consumed by the metaclass, once located it is placed under a private
  class variable so it does not conflict with future subclasses that use
  the same name for other purposes.

  References: #6054

engine

• [engine] [bug] [regression] The Python namedtuple() has the behavior such that the names count
  and index will be served as tuple values if the named tuple includes
  those names; if they are absent, then their behavior as methods of
  collections.abc.Sequence is maintained. Therefore the
  _result.Row and _result.LegacyRow classes have been fixed
  so that they work in this same way, maintaining the expected behavior for
  database rows that have columns named "index" or "count".

  References: #6074

mssql

• [mssql] [bug] [regression] Fixed regression where a new setinputsizes() API that's available for
  pyodbc was enabled, which is apparently incompatible with pyodbc's
  fast_executemany() mode in the absence of more accurate typing information,
  which as of yet is not fully implemented or tested. The pyodbc dialect and
  connector has been modified so that setinputsizes() is not used at all
  unless the parameter use_setinputsizes is passed to the dialect, e.g.
  via _sa.create_engine(), at which point its behavior can be
  customized using the DialectEvents.do_setinputsizes() hook.

  References: #6058

misc

• [bug] [regression] Added back items and values to ColumnCollection class.
  The regression was introduced while adding support for duplicate
  columns in from clauses and selectable in ticket #4753.

  References: #6068