called :attr:`.TypeDecorator.coerce_to_is_types`,
to make it easier to control how comparisons using
``==`` or ``!=`` to ``None`` and boolean types goes
about producing an ``IS`` expression, or a plain
equality expression with a bound parameter.
[ticket:2744]
the joins as is, regardless of the dialect not supporting it. use_labels=True
indicates a higher level of automation and also can maintain the labels
between rewritten and not. use_labels=False indicates a manual use case.
foreign key paths to a table "B", to that table "B", would fail
to produce the "ambiguous join condition" error that would be
reported if you join table "A" directly to "B"; it would instead
produce a join condition with multiple criteria.
[ticket:2738]
regards to the True/False constants. An expression like
``col.is_(True)`` will now render ``col IS true``
on the target platform, rather than converting the True/
False constant to an integer bound parameter.
This allows the ``is_()`` operator to work on MySQL when
given True/False constants.
[ticket:2682]
Python 3, including some important decode/bytes steps.
Issues remain with BLOB types due to driver issues.
Courtesy Ben Trofatter.
- start using util.py3k, we will eventually remove the
sa2to3 fixer entirely
labeled columns when apply_labels() is used; this mode
produces a SELECT where each column is labeled as in
<tablename>_<columnname>, to remove column name collisions
for a multiple table select. The fix is that if two labels
collide when combined with the table name, i.e.
"foo.bar_id" and "foo_bar.id", anonymous aliasing will be
applied to one of the dupes. This allows the ORM to handle
both columns independently; previously, 0.7
would in some cases silently emit a second SELECT for the
column that was "duped", and in 0.8 an ambiguous column error
would be emitted. The "keys" applied to the .c. collection
of the select() will also be deduped, so that the "column
being replaced" warning will no longer emit for any select()
that specifies use_labels, though the dupe key will be given
an anonymous label which isn't generally user-friendly.
[ticket:2702]
Mike Bayer