[sqlalchemy] Flush error during session.merge()
Hello all,
I have a problem using session.merge() in version 0.3.10. I'm trying to merge an
object I'm getting via SOAP from a different server. Here is my code:
self._censusTable = Table('census', self._dbMetaData, autoload=True)
self._censusMapper = mapper(Census, self._censusTable)
self._session = create_session()
def writeCensus(self, soapCensus):
currentTrans = self._session.create_transaction()
try:
sessionCensus = \
self._session.query(Census).get(soapCensus.id)
test = self._session.merge(soapCensus)
currentTrans.commit()
except Exception, e:
currentTrans.rollback()
The result is:
FlushError: New instance [EMAIL PROTECTED] with identity key (class
'census.Census', (12347,), None) conflicts with persistent instance
[EMAIL PROTECTED]
soapCensus is an instance of class Census created by the SOAP library (ZSI),
which should be the same as restoring an object via pickle.
Am I doing something wrong? Do I have to use 0.4 for this to work?
Help would be appreciated.
Thanks,
Kevin
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[sqlalchemy] Re: Flush error during session.merge()
Setting the instance key works fine. Thanks!
Bye,
Kevin
Michael Bayer wrote:
On Oct 24, 2007, at 12:17 PM, Kevin Schmidt wrote:
Hello all,
I have a problem using session.merge() in version 0.3.10. I'm
trying to merge an
object I'm getting via SOAP from a different server. Here is my code:
self._censusTable = Table('census', self._dbMetaData, autoload=True)
self._censusMapper = mapper(Census, self._censusTable)
self._session = create_session()
def writeCensus(self, soapCensus):
currentTrans = self._session.create_transaction()
try:
sessionCensus = \
self._session.query(Census).get(soapCensus.id)
test = self._session.merge(soapCensus)
currentTrans.commit()
except Exception, e:
currentTrans.rollback()
The result is:
FlushError: New instance [EMAIL PROTECTED] with identity key (class
'census.Census', (12347,), None) conflicts with persistent instance
[EMAIL PROTECTED]
soapCensus is an instance of class Census created by the SOAP
library (ZSI),
which should be the same as restoring an object via pickle.
Am I doing something wrong? Do I have to use 0.4 for this to work?
Help would be appreciated.
the soapCensus you're restoring does not have an _instance_key
attribute on it, so the merge() thinks its a pending instance (i.e.
has never been stored in the DB before), and adds it separately to
the session without affecting the current instance already in the
session. when the flush occurs, it conflicts with the existing
instance already in the session. so youd need to stick an
_instance_key on it before merging, which you can do via
soapCensus._instance_key = Session.identity_key(instance=soapCensus).
since people are starting to use merge() now, and consequently
tripping over its awkwardness, it seems like the method is going to
need more attention since I will grant that it probably should be
figuring out that the instance has a primary key on it already. i
added ticket 830 for this.
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[sqlalchemy] Re: Problem with clear_mapper
I can use clear_mappers() because I use mod_python and my mappers are defined during init. Is there any other way I can get this select mapped to my object? non_primary=True (see the docs on mutliple mappers for a class) But that would mean I would define a new non_primary mapper every time, wouldn't it? Is this really a good idea for a server software? Is there maybe a way to update the used table without redefining the mapper? if you are creating all kinds of select() objects from which you want to load instances, simply feed those into query.select() and the appropriate instances will be returned (or use query.instances() with the result of execute()). Thanks, that worked great. Bye, Kevin --~--~-~--~~~---~--~~ 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: Problem with clear_mapper
The stack before is all my classes, so the last one before is the call to class_mapper in the code I send. I had a brief look at the code: def clear_mapper(m): del mapper_registry[m.class_key] attribute_manager.reset_class_managed(m.class_) if hasattr(m.class_, 'c'): del m.class_.c m.class_key.dispose() The traceback comme form del m.class_.c. It looks to me as it tries to delete the columns from the class and fails. I didn't define a mapper without an entity_name, could that be the problem? I can use clear_mappers() because I use mod_python and my mappers are defined during init. Is there any other way I can get this select mapped to my object? Bye, Kevin Michael Bayer wrote: On Apr 25, 2007, at 6:06 PM, Kevin Schmidt wrote: clear_mapper(customMapper) Running that I get: Processing Failure c /usr/lib/python2.5/site-packages/sqlalchemy/orm/__init__.py: 110:clear_mapper] im not sure what that error means, or if thats a full stack trace (if not, a full stack would be helpful). but the clear_mapper() function is going to be generally pretty unreliable since the mapper can be involved in relationships with other mappers. (favor clear_mappers() ) --~--~-~--~~~---~--~~ 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: Problem with clear_mapper
I can use clear_mappers() because I use mod_python and my mappers are defined during init. Is there any other way I can get this select mapped to my object? non_primary=True (see the docs on mutliple mappers for a class) But that would mean I would define a new non_primary mapper every time, wouldn't it? Is this really a good idea for a server software? Is there maybe a way to update the used table without redefining the mapper? Bye, Kevin --~--~-~--~~~---~--~~ 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 with clear_mapper
Hi everyone, I have a problem using the following code (with sqlalchemy 0.3.6 and python2.5): mapperA = mapper(MyClass, self.tables['report_ia'], entity_name = 'REPIA', primary_key=[self.tables['report_ia'].c.id]) mapperB = mapper(MyClass, self.tables['report_ib'], entity_name = 'REPIB', primary_key=[self.tables['report_ib'].c.id]) customSelect = select( [ mapperA.c.id, mapperA.c.uid, func.count(mapperA.c.itemcount).label(itemcount), ], mapperA.c.owner.in_( 'User' ) ), group_by=[mapperA.c.uid, mapperA.c.id] ).alias(totals) customMapper = mapper(MyClass, customSelect, entity_name = temporary, primary_key = [ customSelect.c.id ], ) result = self.session.query(customMapper).select() clear_mapper(customMapper) Running that I get: Processing Failure c /usr/lib/python2.5/site-packages/sqlalchemy/orm/__init__.py:110:clear_mapper] What am I doing wrong here? Any help would be appreciated. Thanks, Kevin --~--~-~--~~~---~--~~ 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 -~--~~~~--~~--~--~---
