- The system of loader options has been entirely rearchitected to build
upon a much more comprehensive base, the :class:`.Load` object. This
base allows any common loader option like :func:`.joinedload`,
:func:`.defer`, etc. to be used in a "chained" style for the purpose
of specifying options down a path, such as ``joinedload("foo").subqueryload("bar")``.
The new system supersedes the usage of dot-separated path names,
multiple attributes within options, and the usage of ``_all()`` options.
- Added a new load option :func:`.orm.load_only`. This allows a series
of column names to be specified as loading "only" those attributes,
deferring the rest.
of groups of column expressions to a :class:`.Query` construct.
The group of columns are returned as a single tuple by default. The
behavior of :class:`.Bundle` can be overridden however to provide
any sort of result processing to the returned row. One example included
is :attr:`.Composite.Comparator.bundle`, which applies a bundled form
of a "composite" mapped attribute.
[ticket:2824]
- The :func:`.composite` construct now maintains the return object
when used in a column-oriented :class:`.Query`, rather than expanding
out into individual columns. This makes use of the new :class:`.Bundle`
feature internally. This behavior is backwards incompatible; to
select from a composite column which will expand out, use
``MyClass.some_composite.clauses``.
of the incoming :class:`.Column` would prevent primary key constraints,
indexes, and foreign key constraints from being correctly reflected.
Also in 0.8.3. [ticket:2811]
instead of relying upon various ``quote=True`` flags being passed around,
these flags are converted into rich string objects with quoting information
included at the point at which they are passed to common schema constructs
like :class:`.Table`, :class:`.Column`, etc. This solves the issue
of various methods that don't correctly honor the "quote" flag such
as :meth:`.Engine.has_table` and related methods. The :class:`.quoted_name`
object is a string subclass that can also be used explicitly if needed;
the object will hold onto the quoting preferences passed and will
also bypass the "name normalization" performed by dialects that
standardize on uppercase symbols, such as Oracle, Firebird and DB2.
The upshot is that the "uppercase" backends can now work with force-quoted
names, such as lowercase-quoted names and new reserved words.
[ticket:2812]
to rely upon server generated version identifiers, using triggers
or other database-provided versioning features, by passing the value
``False``. The ORM will use RETURNING when available to immediately
load the new version identifier, else it will emit a second SELECT.
[ticket:2793]
- The ``eager_defaults`` flag of :class:`.Mapper` will now allow the
newly generated default values to be fetched using an inline
RETURNING clause, rather than a second SELECT statement, for backends
that support RETURNING.
- Added a new variant to :meth:`.ValuesBase.returning` called
:meth:`.ValuesBase.return_defaults`; this allows arbitrary columns
to be added to the RETURNING clause of the statement without interfering
with the compilers usual "implicit returning" feature, which is used to
efficiently fetch newly generated primary key values. For supporting
backends, a dictionary of all fetched values is present at
:attr:`.ResultProxy.returned_defaults`.
- add a glossary entry for RETURNING
- add documentation for version id generation, [ticket:867]
Mike Bayer