Dear Micheal,
Does this mean that with web apps since the session is now weak
referencing that we will no longer have to call Session.remove() to
clear out Sessions? Specifically I'm referencing what Mike Orr wrote in
the pylonscookbook.
Jose
Michael Bayer wrote:
This should hopefully be the last of the beta releases before 0.4.0
is released. The big change in this one is that the ORM Session is
now *weak referencing* by default, with an option to turn on the old
strong referencing behavior. This means that objects in the
session get cleared out automatically when they fall out of scope
within your application. Objects which have pending changes on them
will not get cleared until the session is flushed.
Theres also some refinements to how mappers compile, and it should be
much less likely that you'd get stuck with an uncompiled mapper.
When defining mappers in an inheritance relationship, the superclass
mapper needs to be defined before the corresponding subclass mappers
(which should be how everyone is doing it anyway...I think). Other
than that you can still define mappers in whatever order regardless
of relations to each other.
Besides those, we have a lot of bug fixes and some more enhancements
and speed improvements. We mainly want to see that this one is
stable, works in everyone's environment as well or better than all
the other betas, and then we should be ready to go.
Download 0.4 beta6 at:
http://www.sqlalchemy.org/download.html
changelog (also at http://www.sqlalchemy.org/CHANGES) :
0.4.0beta6
--
- The Session identity map is now *weak referencing* by default, use
weak_identity_map=False to use a regular dict. The weak dict we
are using
is customized to detect instances which are dirty and maintain a
temporary strong reference to those instances until changes are
flushed.
- Mapper compilation has been reorganized such that most compilation
occurs
upon mapper construction. This allows us to have fewer calls to
mapper.compile() and also to allow class-based properties to force a
compilation (i.e. User.addresses == 7 will compile all mappers;
this is
[ticket:758]). The only caveat here is that an inheriting mapper now
looks for its inherited mapper upon construction; so mappers within
inheritance relationships need to be constructed in inheritance order
(which should be the normal case anyway).
- added FETCH to the keywords detected by Postgres to indicate a
result-row holding statement (i.e. in addition to SELECT).
- Added full list of SQLite reserved keywords so that they get escaped
properly.
- Tightened up the relationship between the Query's generation of eager
load aliases, and Query.instances() which actually grabs the eagerly
loaded rows. If the aliases were not specifically generated for that
statement by EagerLoader, the EagerLoader will not take effect
when the
rows are fetched. This prevents columns from being grabbed
accidentally
as being part of an eager load when they were not meant for such,
which
can happen with textual SQL as well as some inheritance
situations. It's
particularly important since the anonymous aliasing of columns uses
simple integer counts now to generate labels.
- Removed parameters argument from clauseelement.compile(),
replaced with
column_keys. The parameters sent to execute() only interact
with the
insert/update statement compilation process in terms of the column
names
present but not the values for those columns. Produces more
consistent
execute/executemany behavior, simplifies things a bit internally.
- Added 'comparator' keyword argument to PickleType. By default,
mutable
PickleType does a deep compare of objects using their dumps()
representation. But this doesn't work for dictionaries. Pickled
objects
which provide an adequate __eq__() implementation can be set up with
PickleType(comparator=operator.eq) [ticket:560]
- Added session.is_modified(obj) method; performs the same history
comparison operation as occurs within a flush operation; setting
include_collections=False gives the same result as is used when
the flush
determines whether or not to issue an UPDATE for the instance's row.
- Added schema argument to Sequence; use this with Postgres /Oracle
when
the sequence is located in an alternate schema. Implements part of
[ticket:584], should fix [ticket:761].
- Fixed reflection of the empty string for mysql enums.
- Changed MySQL dialect to use the older LIMIT offset, limit syntax
instead of LIMIT l OFFSET o for folks using 3.23. [ticket:794]
- Added 'passive_deletes=all' flag to relation(), disables all
nulling-out
of foreign key attributes during a flush where the parent object is
deleted.
- Column defaults and onupdates, executing inline, will
