[sqlalchemy] with_polymorphic mapper option for future classes
Hi *, is there a way to use the with_polymorphic mapper option for classes yet to be defined? My problem is that I have a base class for a number of different database objects. There are few specific leafs classes of which many instances are loaded at once. Currently, I pass with_polymorphic=(*, None) while mapping, but that creates huge query for little effect. I would like to pass the two classes I am interested in but they are defined in other modules (which depends on the module where I map the base class). Is there a way to update the with_polymorphic setting on the base class when mapping the derived class? Greetings, Torsten -- DYNAmore Gesellschaft fuer Ingenieurdienstleistungen mbH Torsten Landschoff Office Dresden Tel: +49-(0)351-4519587 Fax: +49-(0)351-4519561 mailto:torsten.landsch...@dynamore.de http://www.dynamore.de Registration court: Mannheim, HRB: 109659, based in Karlsruhe, Managing director: Prof. Dr. K. Schweizerhof, Dipl.-Math. U. Franz -- 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 sqlalchemy+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/sqlalchemy?hl=en.
[sqlalchemy] how to get last record from a resultset
Hello all, Subject line says it all. Basically what I want to do is to get last record from a result set. I am dealing with a situation where given a date I need to know the last record pertaining to transaction on a given account. yes, it is an accounting/ book keeping software. So I thought there was some thing like .last() method for a resultset? Or even better do we have some thing like session.query(table).last() The problem is that my logic is in place but I know that performance wise it is very dirty to get the list of all records, just to loop till the end and throw away all the rest of the rows. So plese suggest how can I only get just that one (last) record? Happy hacking. Krishnakant. -- 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 sqlalchemy+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/sqlalchemy?hl=en.
Re: [sqlalchemy] with_polymorphic mapper option for future classes
perhaps we'd want to establish mapper.with_polymorphic as a setter that will perform the requisite validations on it whenever it is set.I think you can set it right now on the mapper at any point, it doesn't seem to be consulted in any configurational way. The only validations that occur are on the second argument if it is not None. Give that a try first. There is a hackish recipe we have at http://www.sqlalchemy.org/trac/wiki/UsageRecipes/DeclarativeAbstractConcreteBase which illustrates how to set up a mapper with declarative where the mapper() is created later, but it would be nice if we could provide the callable approach of relationship() for things like this at some point in the future. Also I don't like with_polymorphic very much but I don't have a better idea at the moment. On Jul 20, 2011, at 8:36 AM, Torsten Landschoff wrote: Hi *, is there a way to use the with_polymorphic mapper option for classes yet to be defined? My problem is that I have a base class for a number of different database objects. There are few specific leafs classes of which many instances are loaded at once. Currently, I pass with_polymorphic=(*, None) while mapping, but that creates huge query for little effect. I would like to pass the two classes I am interested in but they are defined in other modules (which depends on the module where I map the base class). Is there a way to update the with_polymorphic setting on the base class when mapping the derived class? Greetings, Torsten -- DYNAmore Gesellschaft fuer Ingenieurdienstleistungen mbH Torsten Landschoff Office Dresden Tel: +49-(0)351-4519587 Fax: +49-(0)351-4519561 mailto:torsten.landsch...@dynamore.de http://www.dynamore.de Registration court: Mannheim, HRB: 109659, based in Karlsruhe, Managing director: Prof. Dr. K. Schweizerhof, Dipl.-Math. U. Franz -- 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 sqlalchemy+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/sqlalchemy?hl=en. -- 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 sqlalchemy+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/sqlalchemy?hl=en.
Re: [sqlalchemy] Occasional ProgrammingError in threaded environment
On Jul 20, 2011, at 1:50 AM, Arthur Kopatsy wrote: Hi, My web application has a controller that spawns multiple threads using a thread pool. Each of them has its own session (I store it in thread local). Occasionally (1 out of 100 or more) I get really strange errors that really look like corrupted queries. My guess is that it may be due to my thread pooling and the fact that a session may be reused for multiple jobs. Yes this is most likely basic sharing of a Session and/or related state between threads. The stack trace specifically is the access of an unloaded or expired attribute on a persistent object - this consults the Session to refresh the object.Accesses like these need to be kept local to a single thread. -- 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 sqlalchemy+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/sqlalchemy?hl=en.
Re: [sqlalchemy] how to get last record from a resultset
I think, reversing the sort and getting the first record will do. 20-07-2011 16:32, Krishnakant Mane yazmış: Hello all, Subject line says it all. Basically what I want to do is to get last record from a result set. I am dealing with a situation where given a date I need to know the last record pertaining to transaction on a given account. yes, it is an accounting/ book keeping software. So I thought there was some thing like .last() method for a resultset? Or even better do we have some thing like session.query(table).last() The problem is that my logic is in place but I know that performance wise it is very dirty to get the list of all records, just to loop till the end and throw away all the rest of the rows. So plese suggest how can I only get just that one (last) record? Happy hacking. Krishnakant. -- 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 sqlalchemy+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/sqlalchemy?hl=en.
Re: [sqlalchemy] how to get last record from a resultset
Well, there won't be a consistent result using sort because there might be 10 rows with same voucher code and same account code. That's exactly the challenge so I don't know how sort will help. If we can invert the entire resultset having the last record become first, then its worth while. But again, I don't want the entire set of rows in the first place. I just want that particular row. Happy hacking. Krishnakant. On 20/07/11 19:20, Timuçin Kızılay wrote: I think, reversing the sort and getting the first record will do. 20-07-2011 16:32, Krishnakant Mane yazmış: Hello all, Subject line says it all. Basically what I want to do is to get last record from a result set. I am dealing with a situation where given a date I need to know the last record pertaining to transaction on a given account. yes, it is an accounting/ book keeping software. So I thought there was some thing like .last() method for a resultset? Or even better do we have some thing like session.query(table).last() The problem is that my logic is in place but I know that performance wise it is very dirty to get the list of all records, just to loop till the end and throw away all the rest of the rows. So plese suggest how can I only get just that one (last) record? Happy hacking. Krishnakant. -- 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 sqlalchemy+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/sqlalchemy?hl=en.
RE: [sqlalchemy] how to get last record from a resultset
If you don't have something consistent to sort by, then I'm not sure that the last record is meaningful, is it? If you have 10 rows with the same voucher code and account code (and there is nothing else to uniquely identify them, such as a more precise timestamp, or an auto-incrementing ID), then as far as the result set is concerned, there is nothing special about the last row. The database could be giving them to you in any order. I'm sure I'm misunderstanding your situation - perhaps you could describe your schema and why you need this information, and then we might be more help. Simon -Original Message- From: sqlalchemy@googlegroups.com [mailto:sqlalchemy@googlegroups.com] On Behalf Of Krishnakant Mane Sent: 20 July 2011 15:16 To: sqlalchemy@googlegroups.com Cc: Timuçin Kızılay Subject: Re: [sqlalchemy] how to get last record from a resultset Well, there won't be a consistent result using sort because there might be 10 rows with same voucher code and same account code. That's exactly the challenge so I don't know how sort will help. If we can invert the entire resultset having the last record become first, then its worth while. But again, I don't want the entire set of rows in the first place. I just want that particular row. Happy hacking. Krishnakant. On 20/07/11 19:20, Timuçin Kızılay wrote: I think, reversing the sort and getting the first record will do. 20-07-2011 16:32, Krishnakant Mane yazmış: Hello all, Subject line says it all. Basically what I want to do is to get last record from a result set. I am dealing with a situation where given a date I need to know the last record pertaining to transaction on a given account. yes, it is an accounting/ book keeping software. So I thought there was some thing like .last() method for a resultset? Or even better do we have some thing like session.query(table).last() The problem is that my logic is in place but I know that performance wise it is very dirty to get the list of all records, just to loop till the end and throw away all the rest of the rows. So plese suggest how can I only get just that one (last) record? Happy hacking. Krishnakant. -- 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 sqlalchemy+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/sqlalchemy?hl=en. -- 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 sqlalchemy+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/sqlalchemy?hl=en.
[sqlalchemy] Re: Occasional ProgrammingError in threaded environment
Hi Michael, I indeed had a object hanging around and being shared across threads... Thanks for the hint, you saved my week! Arthur On Jul 20, 6:46 am, Michael Bayer mike...@zzzcomputing.com wrote: On Jul 20, 2011, at 1:50 AM, Arthur Kopatsy wrote: Hi, My web application has a controller that spawns multiple threads using a thread pool. Each of them has its own session (I store it in thread local). Occasionally (1 out of 100 or more) I get really strange errors that really look like corrupted queries. My guess is that it may be due to my thread pooling and the fact that a session may be reused for multiple jobs. Yes this is most likely basic sharing of a Session and/or related state between threads. The stack trace specifically is the access of an unloaded or expired attribute on a persistent object - this consults the Session to refresh the object. Accesses like these need to be kept local to a single thread. -- 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 sqlalchemy+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/sqlalchemy?hl=en.
[sqlalchemy] order_by with property of related table
Hi!
I have two tables: A and B defined something like that:
A:
Column('id', Integer, primary_key=True),
Column('name', Unicode(256)),
Column('b_id', Integer, ForeignKey('b.id'))
B:
Column('id', Integer, primary_key=True),
Column('name', Unicode(256)),
mapper of A is created with:
properties={
'b': relation(B, primaryjoin=A.b_id == B.id, lazy=False),
}
(lazy = False is important in this case)
How can I select all elements from A sorted by B.name? I checked that
I can't use
SESSION.query(A).order_by(B.name)
because it's not working - query(A) consist of JOIN with B table and B
table has alias B_1 in this query and sqlalchemy interprets
order_by(B.name) as ORDER BY B.name but there is no B alias in
query(A).
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[sqlalchemy] py32 TypeError: unorderable types: str() int()
declarative_base
tmp = session.query(Opt).all()
session.add(Opt(key='a', value='b'))
session.commit()
File /usr/local/lib/python3.2/dist-packages/SQLAlchemy-0.7.1-
py3.2.egg/sqlalchemy/orm/session.py, line 617, in commit
self.transaction.commit()
File /usr/local/lib/python3.2/dist-packages/SQLAlchemy-0.7.1-
py3.2.egg/sqlalchemy/orm/session.py, line 293, in commit
self._prepare_impl()
File /usr/local/lib/python3.2/dist-packages/SQLAlchemy-0.7.1-
py3.2.egg/sqlalchemy/orm/session.py, line 277, in _prepare_impl
self.session.flush()
File /usr/local/lib/python3.2/dist-packages/SQLAlchemy-0.7.1-
py3.2.egg/sqlalchemy/orm/session.py, line 1473, in flush
self._flush(objects)
File /usr/local/lib/python3.2/dist-packages/SQLAlchemy-0.7.1-
py3.2.egg/sqlalchemy/orm/session.py, line 1542, in _flush
flush_context.execute()
File /usr/local/lib/python3.2/dist-packages/SQLAlchemy-0.7.1-
py3.2.egg/sqlalchemy/orm/unitofwork.py, line 327, in execute
rec.execute(self)
File /usr/local/lib/python3.2/dist-packages/SQLAlchemy-0.7.1-
py3.2.egg/sqlalchemy/orm/unitofwork.py, line 471, in execute
uow
File /usr/local/lib/python3.2/dist-packages/SQLAlchemy-0.7.1-
py3.2.egg/sqlalchemy/orm/mapper.py, line 1870, in _save_obj
for state in _sort_states(states):
File /usr/local/lib/python3.2/dist-packages/SQLAlchemy-0.7.1-
py3.2.egg/sqlalchemy/orm/mapper.py, line 2808, in _sort_states
return sorted(states, key=operator.attrgetter('sort_key'))
TypeError: unorderable types: str() int()
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Re: [sqlalchemy] py32 TypeError: unorderable types: str() int()
Can I ask that you put a little more effort into providing context / mappings /
specifics for this stack trace (see guidelines at
http://www.sqlalchemy.org/support.html#mailinglist ) ? Clearly If I make a
sample Opt() class with two fields and commit it, no such error occurs. There
is some suggestion of inappropriate assignment of a string or int to an
attribute which expects the opposite here.
On Jul 20, 2011, at 1:26 PM, ddarko wrote:
declarative_base
tmp = session.query(Opt).all()
session.add(Opt(key='a', value='b'))
session.commit()
File /usr/local/lib/python3.2/dist-packages/SQLAlchemy-0.7.1-
py3.2.egg/sqlalchemy/orm/session.py, line 617, in commit
self.transaction.commit()
File /usr/local/lib/python3.2/dist-packages/SQLAlchemy-0.7.1-
py3.2.egg/sqlalchemy/orm/session.py, line 293, in commit
self._prepare_impl()
File /usr/local/lib/python3.2/dist-packages/SQLAlchemy-0.7.1-
py3.2.egg/sqlalchemy/orm/session.py, line 277, in _prepare_impl
self.session.flush()
File /usr/local/lib/python3.2/dist-packages/SQLAlchemy-0.7.1-
py3.2.egg/sqlalchemy/orm/session.py, line 1473, in flush
self._flush(objects)
File /usr/local/lib/python3.2/dist-packages/SQLAlchemy-0.7.1-
py3.2.egg/sqlalchemy/orm/session.py, line 1542, in _flush
flush_context.execute()
File /usr/local/lib/python3.2/dist-packages/SQLAlchemy-0.7.1-
py3.2.egg/sqlalchemy/orm/unitofwork.py, line 327, in execute
rec.execute(self)
File /usr/local/lib/python3.2/dist-packages/SQLAlchemy-0.7.1-
py3.2.egg/sqlalchemy/orm/unitofwork.py, line 471, in execute
uow
File /usr/local/lib/python3.2/dist-packages/SQLAlchemy-0.7.1-
py3.2.egg/sqlalchemy/orm/mapper.py, line 1870, in _save_obj
for state in _sort_states(states):
File /usr/local/lib/python3.2/dist-packages/SQLAlchemy-0.7.1-
py3.2.egg/sqlalchemy/orm/mapper.py, line 2808, in _sort_states
return sorted(states, key=operator.attrgetter('sort_key'))
TypeError: unorderable types: str() int()
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[sqlalchemy] Re: py32 TypeError: unorderable types: str() int()
That is very strange. I am from a few hours struggling with this ...
stripped application on the first ...
There is nothing else.
Ordinary simple table. On it a select and an insert (with ORM, of
course).
Rest a while and try to prepare a complete test case. Unless I find a
solution on the way :]
On Jul 20, 7:38 pm, Michael Bayer mike...@zzzcomputing.com wrote:
Can I ask that you put a little more effort into providing context / mappings
/ specifics for this stack trace (see guidelines
athttp://www.sqlalchemy.org/support.html#mailinglist) ? Clearly If I make a
sample Opt() class with two fields and commit it, no such error occurs.
There is some suggestion of inappropriate assignment of a string or int to an
attribute which expects the opposite here.
On Jul 20, 2011, at 1:26 PM, ddarko wrote:
declarative_base
tmp = session.query(Opt).all()
session.add(Opt(key='a', value='b'))
session.commit()
File /usr/local/lib/python3.2/dist-packages/SQLAlchemy-0.7.1-
py3.2.egg/sqlalchemy/orm/session.py, line 617, in commit
self.transaction.commit()
File /usr/local/lib/python3.2/dist-packages/SQLAlchemy-0.7.1-
py3.2.egg/sqlalchemy/orm/session.py, line 293, in commit
self._prepare_impl()
File /usr/local/lib/python3.2/dist-packages/SQLAlchemy-0.7.1-
py3.2.egg/sqlalchemy/orm/session.py, line 277, in _prepare_impl
self.session.flush()
File /usr/local/lib/python3.2/dist-packages/SQLAlchemy-0.7.1-
py3.2.egg/sqlalchemy/orm/session.py, line 1473, in flush
self._flush(objects)
File /usr/local/lib/python3.2/dist-packages/SQLAlchemy-0.7.1-
py3.2.egg/sqlalchemy/orm/session.py, line 1542, in _flush
flush_context.execute()
File /usr/local/lib/python3.2/dist-packages/SQLAlchemy-0.7.1-
py3.2.egg/sqlalchemy/orm/unitofwork.py, line 327, in execute
rec.execute(self)
File /usr/local/lib/python3.2/dist-packages/SQLAlchemy-0.7.1-
py3.2.egg/sqlalchemy/orm/unitofwork.py, line 471, in execute
uow
File /usr/local/lib/python3.2/dist-packages/SQLAlchemy-0.7.1-
py3.2.egg/sqlalchemy/orm/mapper.py, line 1870, in _save_obj
for state in _sort_states(states):
File /usr/local/lib/python3.2/dist-packages/SQLAlchemy-0.7.1-
py3.2.egg/sqlalchemy/orm/mapper.py, line 2808, in _sort_states
return sorted(states, key=operator.attrgetter('sort_key'))
TypeError: unorderable types: str() int()
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