[sqlalchemy] Re: multiple mapper extensions
Michael Bayer wrote: On Jul 30, 2007, at 4:58 PM, Jonathan LaCour wrote: Michael Bayer wrote: its a model taken from the way event loops usually work; any consumer along the event chain is allowed to say, ive consumed the event and stop further handlers from dealing with it. we can certainly change the names around into something less ridiculous. unfortuantely, changing it so that no return value, or None, does *not* short circuit the chain runs a slight risk that someone is actually using it that way. So we might need to change it such that if your before_insert returns None, an error is raised, and youre forced to return a specific value indicating the next activity...otherwise someone's upgrade might silently fail. Fair enough, I suppose. I think I can get over it, for the most part. It might just be an issue of cognitive dissonance because of the naming convention or how its described in the documentation. i think a name change is probably in order at the very least. r3130 in the trunk implements a name change- EXT_CONTINUE will propagate the hook to the next extension or back to the base implementation. EXT_STOP will halt propagation. it's only a name and doc change: EXT_CONTINUE = EXT_PASS = object() EXT_STOP = object() EXT_STOP is just a feel-good value. the general rule of halt on any return value but EXT_CONTINUE is unchanged. --~--~-~--~~~---~--~~ You received this message because you are subscribed to the Google Groups sqlalchemy group. To post to this group, send email to sqlalchemy@googlegroups.com To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/sqlalchemy?hl=en -~--~~~~--~~--~--~---
[sqlalchemy] all() or list() ?
Hello, I'm realizing that I've been using .list() to query objects. But all the examples in the docs talk about .all(). What's the difference ? Should I switch to .all() rather than .list() ? Will list be deprecated in 0.4 ? Regards, -- Alexandre CONRAD --~--~-~--~~~---~--~~ You received this message because you are subscribed to the Google Groups sqlalchemy group. To post to this group, send email to sqlalchemy@googlegroups.com To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/sqlalchemy?hl=en -~--~~~~--~~--~--~---
[sqlalchemy] Re: all() or list() ?
On 8/1/07, Alexandre CONRAD [EMAIL PROTECTED] wrote: I'm realizing that I've been using .list() to query objects. But all the examples in the docs talk about .all(). What's the difference ? Should I switch to .all() rather than .list() ? Will list be deprecated in 0.4 ? Exactly. list() is the old way, all() is the 0.4 way. -- Gaëtan de Menten http://openhex.org --~--~-~--~~~---~--~~ You received this message because you are subscribed to the Google Groups sqlalchemy group. To post to this group, send email to sqlalchemy@googlegroups.com To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/sqlalchemy?hl=en -~--~~~~--~~--~--~---
[sqlalchemy] Re: all() or list() ?
Gaetan de Menten wrote: What's the difference ? Should I switch to .all() rather than .list() ? Will list be deprecated in 0.4 ? Exactly. list() is the old way, all() is the 0.4 way. Thanks Gaetan, I'll clean up my code to be compliant with 0.4. Regards, -- Alexandre CONRAD --~--~-~--~~~---~--~~ You received this message because you are subscribed to the Google Groups sqlalchemy group. To post to this group, send email to sqlalchemy@googlegroups.com To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/sqlalchemy?hl=en -~--~~~~--~~--~--~---
[sqlalchemy] Re: multiple mapper extensions
jason kirtland wrote: i think a name change is probably in order at the very least. r3130 in the trunk implements a name change- EXT_CONTINUE will propagate the hook to the next extension or back to the base implementation. EXT_STOP will halt propagation. it's only a name and doc change: EXT_CONTINUE = EXT_PASS = object() EXT_STOP = object() EXT_STOP is just a feel-good value. the general rule of halt on any return value but EXT_CONTINUE is unchanged. Perfect. This now makes total sense, thanks for doing this! -- Jonathan LaCour http://cleverdevil.org --~--~-~--~~~---~--~~ You received this message because you are subscribed to the Google Groups sqlalchemy group. To post to this group, send email to sqlalchemy@googlegroups.com To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/sqlalchemy?hl=en -~--~~~~--~~--~--~---
[sqlalchemy] Re: cannot read msg...
yes Glauco wrote: can someone read me? Glauco -- Alexandre CONRAD --~--~-~--~~~---~--~~ You received this message because you are subscribed to the Google Groups sqlalchemy group. To post to this group, send email to sqlalchemy@googlegroups.com To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/sqlalchemy?hl=en -~--~~~~--~~--~--~---
[sqlalchemy] cannot read msg...
can someone read me? Glauco -- ++ Glauco Uri - Programmatore glauco(at)allevatori.com Sfera Carta Software(r) [EMAIL PROTECTED] Via Bazzanese,69 Casalecchio di Reno(BO) - Tel. 051591054 ++ --~--~-~--~~~---~--~~ You received this message because you are subscribed to the Google Groups sqlalchemy group. To post to this group, send email to sqlalchemy@googlegroups.com To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/sqlalchemy?hl=en -~--~~~~--~~--~--~---
[sqlalchemy] TypeError with 0.4 and python 2.3
Right now, importing sqlalchemy on python 2.3 is broken. __name__ is readonly in 2.3, so the import fails: from sqlalchemy import * Traceback (most recent call last): File stdin, line 1, in ? File /home/watsond/python_packages/sqlalchemy/__init__.py, line 9, in ? from sqlalchemy.schema import * File /home/watsond/python_packages/sqlalchemy/schema.py, line 1087, in ? class MetaData(SchemaItem): File /home/watsond/python_packages/sqlalchemy/schema.py, line 1180, in MetaData connect = util.deprecated(connect) File /home/watsond/python_packages/sqlalchemy/util.py, line 552, in deprecated func_with_warning.__name__ = func.__name__ TypeError: readonly attribute I'm not sure what side-effects it would cause (my guess would be harder-to-read tracebacks when calling deprecated methods?), but commenting out the assignment got me up and running again. --~--~-~--~~~---~--~~ You received this message because you are subscribed to the Google Groups sqlalchemy group. To post to this group, send email to sqlalchemy@googlegroups.com To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/sqlalchemy?hl=en -~--~~~~--~~--~--~---
[sqlalchemy] Re: right outer join (newbie)
we currently dont have a right outer join. but this is not by accident...theres really no use case for a right outer join, which are more easily written as left outer joins. some good articles on whats wrong with RIGHT outer join as well as FULL outer join: http://weblogs.sqlteam.com/jeffs/archive/2006/03/14/9289.aspx http://weblogs.sqlteam.com/jeffs/archive/2007/04/19/Full-Outer- Joins.aspx?x=1 On Aug 1, 2007, at 5:56 PM, mc wrote: Hi, I read in the docs about joins and saw an example for left outer join, though I didn't understand where the left was specified. How is a right outer join specified? --~--~-~--~~~---~--~~ You received this message because you are subscribed to the Google Groups sqlalchemy group. To post to this group, send email to sqlalchemy@googlegroups.com To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/sqlalchemy?hl=en -~--~~~~--~~--~--~---
[sqlalchemy] Atomic update to balance in transaction with ORM changes
I have ORM mapped tables with a schema like the following: --- Table 'users': user_id integer username text balance integer Table 'products': product_id integer cost integer Table 'user_products': user_id integer product_id integer --- when a user buys a product, I need to add a user_product record for them, and deduct the cost of the product from the user's balance. I need to do the latter in an atomic fashion, however (eg, UPDATE users SET balance = balance - ? WHERE user_id = ?) in the same transaction as the ORM changes to create the user_products record. Ideally, I need to update the relevant User object with the updated balance, too. Can anyone provide me with a quick overview of how to do this? Thanks, Nick Johnson --~--~-~--~~~---~--~~ You received this message because you are subscribed to the Google Groups sqlalchemy group. To post to this group, send email to sqlalchemy@googlegroups.com To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/sqlalchemy?hl=en -~--~~~~--~~--~--~---
[sqlalchemy] Re: Atomic update to balance in transaction with ORM changes
On Aug 1, 2007, at 7:26 PM, Nick Johnson wrote:
I have ORM mapped tables with a schema like the following:
---
Table 'users':
user_id integer
username text
balance integer
Table 'products':
product_id integer
cost integer
Table 'user_products':
user_id integer
product_id integer
---
when a user buys a product, I need to add a user_product record for
them, and deduct the cost of the product from the user's balance. I
need to do the latter in an atomic fashion, however (eg, UPDATE users
SET balance = balance - ? WHERE user_id = ?) in the same transaction
as the ORM changes to create the user_products record. Ideally, I need
to update the relevant User object with the updated balance, too.
Can anyone provide me with a quick overview of how to do this?
if you use a SessionTransaction (which is being simplified in the
next release), and then load your User with_lockmode as such:
user = session.query(User).with_lockmode('update').load(userid)
that will in all cases, whether userid was already loaded or not,
issue a SELECT...FOR UPDATE on the row containing that user id, and
it will overwrite all attributes on your User object with the values
retrieved from the database. so now, the balance attribute on
'user' should be the latest value, and the row should be locked
against further changes.
then, modify the balance attribute on your User object, modify
other attributes as needed, and flush(). after that, commit the
transaction.
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[sqlalchemy] Re: Atomic update to balance in transaction with ORM changes
On Aug 1, 8:35 pm, Nick Johnson [EMAIL PROTECTED] wrote: Thanks, I'll try that. Is there a way I can do this without locking, though, such as by adding my own UPDATE query to the transaction? uh sure probably with a MapperExtension that does an after_update() for the User mapper...just issues that SQL. though with that arrangement, you need to be careful that the mapper doesnt update the column beforehand with the balance value on your User. Theres a feature we've discussed which is probably the best way to do this, you'd just say: user.balance = user_table.c.balance + 1 ...the mapper intercepts the ClauseElement and uses that as the UPDATE value. so maybe ill put that in 0.4. --~--~-~--~~~---~--~~ You received this message because you are subscribed to the Google Groups sqlalchemy group. To post to this group, send email to sqlalchemy@googlegroups.com To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/sqlalchemy?hl=en -~--~~~~--~~--~--~---
[sqlalchemy] Problem using multiple mappers for one class
Hi,
I ran into an error trying to use two mappers for the same class. I
encounter the error AttributeError: type object 'MyObject' has no
attribute 'my_attribute'. Using the first mapper before creating the
other seems to corrupt the mapped class. Here is an example:
from sqlalchemy import *
from sqlalchemy.orm import *
uri = r'sqlite:///bug.db'
metadata = MetaData()
class AA(object):
pass
class BB(object):
pass
aa_table = Table('aas', metadata,
Column('id', Integer, primary_key=True),
Column('stuff', Integer, default=1))
bb_table = Table('bbs', metadata,
Column('id', Integer, primary_key=True),
Column('other_stuff', Integer, default=2),
Column('aa_id', Integer, ForeignKey('aas.id')))
aa_first_mapper = mapper(AA, aa_table, entity_name='first')
bb_first_mapper = mapper(BB, bb_table, entity_name='first')
aa_first_mapper.add_property('bbs', relation(bb_first_mapper,
backref='aa'))
def fill_db():
metadata.connect(uri)
metadata.bind.echo = False
session = create_session()
metadata.drop_all()
metadata.create_all()
aa1 = AA()
bb1 = BB()
bb1.aa = aa1
bb2 = BB()
bb2.aa = aa1
session.save(aa1, entity_name='first')
session.save(bb1, entity_name='first')
session.save(bb2, entity_name='first')
session.flush()
session.clear()
fill_db()
def access_db():
session = create_session()
aas = session.query(aa_first_mapper).select()
print 'bbs in aas[0] count =', len(aas[0].bbs)
access_db()
# commenting these 3 lines of code will fix the bug!?
aa_second_mapper = mapper(AA, aa_table, entity_name='second')
bb_second_mapper = mapper(BB, bb_table, entity_name='second')
aa_second_mapper.add_property('bbs', relation(bb_second_mapper,
backref='aa'))
access_db() # crash :(
From what I understand of the documentation, I should be able to do
this using different entity names for the different mappers. Or is it
that once an object has been committed to the db using a certain
entity name, it can only be manipulated with this same entity name?
Thanks
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[sqlalchemy] Re: Problem using multiple mappers for one class
On Aug 1, 9:45 pm, Gabriel Cote [EMAIL PROTECTED] wrote: From what I understand of the documentation, I should be able to do this using different entity names for the different mappers. Or is it that once an object has been committed to the db using a certain entity name, it can only be manipulated with this same entity name? the only real problem with the above is that your second two mappers are uncompiled. this because you create them but don't reference them in any way, and also because your usage of the mapped classes, which also triggers a compile, precedes their creation so they didn't get compiled there either. either define them up above or just say compile_mappers() and you're a go. also, when an object is saved to the session with a particular entity name (or loaded with that mapper), its got an _entity_name attribute which marks it as linked to that mapper. if you want to switch the entity name around you can use obj = session.merge(obj, entity_name=newname). --~--~-~--~~~---~--~~ You received this message because you are subscribed to the Google Groups sqlalchemy group. To post to this group, send email to sqlalchemy@googlegroups.com To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/sqlalchemy?hl=en -~--~~~~--~~--~--~---
