1.4.6

Released: April 6, 2021

orm

• [orm] [bug] [regression] Fixed regression where a deprecated form of _orm.Query.join() were
  used, passing a series of entities to join from without any ON clause in a
  single _orm.Query.join() call, would fail to function correctly.

  References: #6203

• [orm] [bug] [regression] Fixed critical regression where the _orm.Query.yield_per() method in
  the ORM would set up the internal _engine.Result to yield chunks
  at a time, however made use of the new _engine.Result.unique() method
  which uniques across the entire result. This would lead to lost rows since
  the ORM is using id(obj) as the uniquing function, which leads to
  repeated identifiers for new objects as already-seen objects are garbage
  collected. 1.3's behavior here was to "unique" across each chunk, which
  does not actually produce "uniqued" results when results are yielded in
  chunks. As the _orm.Query.yield_per() method is already explicitly
  disallowed when joined eager loading is in place, which is the primary
  rationale for the "uniquing" feature, the "uniquing" feature is now turned
  off entirely when _orm.Query.yield_per() is used.

  This regression only applies to the legacy _orm.Query object; when
  using :term:2.0 style execution, "uniquing" is not automatically applied.
  To prevent the issue from arising from explicit use of
  _engine.Result.unique(), an error is now raised if rows are fetched
  from a "uniqued" ORM-level _engine.Result if any
  yield per <orm_queryguide_yield_per> API is also in use, as the
  purpose of yield_per is to allow for arbitrarily large numbers of rows,
  which cannot be uniqued in memory without growing the number of entries to
  fit the complete result size.

  Unknown interpreted text role "term".

  References: #6206

sql

• [sql] [bug] [mssql] [oracle] [regression] Fixed further regressions in the same area as that of #6173 released in
  1.4.5, where a "postcompile" parameter, again most typically those used for
  LIMIT/OFFSET rendering in Oracle and SQL Server, would fail to be processed
  correctly if the same parameter rendered in multiple places in the
  statement.

  References: #6202

• [sql] [bug] Executing a _sql.Subquery using _engine.Connection.execute()
  is deprecated and will emit a deprecation warning; this use case was an
  oversight that should have been removed from 1.4. The operation will now
  execute the underlying _sql.Select object directly for backwards
  compatibility. Similarly, the _sql.CTE class is also not
  appropriate for execution. In 1.3, attempting to execute a CTE would result
  in an invalid "blank" SQL statement being executed; since this use case was
  not working it now raises _exc.ObjectNotExecutableError.
  Previously, 1.4 was attempting to execute the CTE as a statement however it
  was working only erratically.

  References: #6204

schema

• [schema] [bug] The _schema.Table object now raises an informative error message if
  it is instantiated without passing at least the _schema.Table.name
  and _schema.Table.metadata arguments positionally. Previously, if
  these were passed as keyword arguments, the object would silently fail to
  initialize correctly.

  This change is also backported to: 1.3.25

  References: #6135

mypy

• [mypy] [bug] Applied a series of refactorings and fixes to accommodate for Mypy
  "incremental" mode across multiple files, which previously was not taken
  into account. In this mode the Mypy plugin has to accommodate Python
  datatypes expressed in other files coming in with less information than
  they have on a direct run.

  Additionally, a new decorator _orm.declarative_mixin() is added,
  which is necessary for the Mypy plugin to be able to definifitely identify
  a Declarative mixin class that is otherwise not used inside a particular
  Python file.

  References: #6147

• [mypy] [bug] Fixed issue where the Mypy plugin would fail to interpret the
  "collection_class" of a relationship if it were a callable and not a class.
  Also improved type matching and error reporting for collection-oriented
  relationships.

  References: #6205

asyncio

• [asyncio] [usecase] [postgresql] Added accessors .sqlstate and synonym .pgcode to the .orig
  attribute of the SQLAlchemy exception class raised by the asyncpg DBAPI
  adapter, that is, the intermediary exception object that wraps on top of
  that raised by the asyncpg library itself, but below the level of the
  SQLAlchemy dialect.

  References: #6199