Re: [sqlalchemy] Modifying a cascaded object directly and then saving its parent
Thanks for the very detailed explanation :) I think I'll tweak the application flow to avoid this kind of thing altogether... Many thanks again! -- You received this message because you are subscribed to the Google Groups sqlalchemy group. To unsubscribe from this group and stop receiving emails from it, send an email to sqlalchemy+unsubscr...@googlegroups.com. To post to this group, send email to sqlalchemy@googlegroups.com. Visit this group at http://groups.google.com/group/sqlalchemy. For more options, visit https://groups.google.com/d/optout.
[sqlalchemy] Modifying a cascaded object directly and then saving its parent
Hi everyone! I have a client-server application where sometimes I need to modify a cascaded member of a one-to-many relation directly, that is by saving itself instead of its parent. This works, but if later the user *does* save the parent, I get a A conflicting state is already present in the identity map error, and I don't know if I'm simply doing something I'm not supposed to :) I narrowed down the issue to this example: from sqlalchemy import Column, String, Integer, Table, ForeignKey from sqlalchemy.engine import create_engine from sqlalchemy.orm import sessionmaker, relationship from sqlalchemy.ext.declarative import declarative_base Base = declarative_base() class Child(Base): __tablename__ = children id = Column(Integer, primary_key=True) parent_id = Column(Integer, ForeignKey(parents.id)) class Parent(Base): __tablename__ = parents id = Column(Integer, primary_key=True) children = relationship(Child, cascade=save-update, uselist=True) en = create_engine(sqlite:///:memory:, echo=True) Base.metadata.create_all(en) maker = sessionmaker(en) session = maker(autocommit=True) # Save a parent with a child par = Parent() par.children = [ Child() ] session.add(par) session.flush() child_id = par.children[0].id # For later # Clean the session (simulate another client-server session) session.expunge_all() # Reload the children q = session.query(Child) q = q.filter(Child.id == child_id) child_reloaded = q.first() # Reassign to the parent and save par.children = [child_reloaded] session.add(par) I tested this on SQLalchemy 0.9.4: Traceback (most recent call last): File testsa.py, line 44, in module session.add(par) File /home/joril/src/newprg/branches/sqla09/sqlalchemy/orm/session.py, line 1478, in add self._save_or_update_state(state) File /home/joril/src/newprg/branches/sqla09/sqlalchemy/orm/session.py, line 1497, in _save_or_update_state self._save_or_update_impl(st_) File /home/joril/src/newprg/branches/sqla09/sqlalchemy/orm/session.py, line 1746, in _save_or_update_impl self._update_impl(state) File /home/joril/src/newprg/branches/sqla09/sqlalchemy/orm/session.py, line 1739, in _update_impl self.identity_map.add(state) File /home/joril/src/newprg/branches/sqla09/sqlalchemy/orm/identity.py, line 119, in add % (key, )) AssertionError: A conflicting state is already present in the identity map for key (class '__main__.Child', (1,)) Is this supposed to happen? Many thanks! -- You received this message because you are subscribed to the Google Groups sqlalchemy group. To unsubscribe from this group and stop receiving emails from it, send an email to sqlalchemy+unsubscr...@googlegroups.com. To post to this group, send email to sqlalchemy@googlegroups.com. Visit this group at http://groups.google.com/group/sqlalchemy. For more options, visit https://groups.google.com/d/optout.
Re: [sqlalchemy] Using value from main query inside subquery
On Friday, April 26, 2013 12:25:42 AM UTC+2, Michael Bayer wrote: this will work out of the box in 0.8 as auto-correlation has been improved a lot. in 0.7 you can add correlate() explicitly: Nice, many thanks :) -- You received this message because you are subscribed to the Google Groups sqlalchemy group. To unsubscribe from this group and stop receiving emails from it, send an email to sqlalchemy+unsubscr...@googlegroups.com. To post to this group, send email to sqlalchemy@googlegroups.com. Visit this group at http://groups.google.com/group/sqlalchemy?hl=en. For more options, visit https://groups.google.com/groups/opt_out.
[sqlalchemy] Using value from main query inside subquery
Hi everyone! I have this working query: select * from A join B on A.id = B.a_id where exists (select 1 from C where A.id = C.a_id and C.value B.value) and I tried to implement it like this: q = Session.query(entities.A) q = q.join((entities.B, entities.A.id == entities.B.a_id)) q = q.filter(entities.A.list_of_Cs.any(entities.C.value entities.B.value) but the generated SQL looks like: SELECT [...fields...] FROM a JOIN b ON a.id = b.a_id WHERE EXISTS (SELECT 1 FROM C, B WHERE A.id = C.a_id AND C.value B.value) As you can see, the inner select doesn't get B.value from the main query as in my original one, instead it introduces a new join between C and B... I tried replacing entities.B like this: b_alias = entities.B.__table__.alias() but I still get a join inside the subquery... What am I missing? Many thanks! (SQLAlchemy 0.7.9) -- You received this message because you are subscribed to the Google Groups sqlalchemy group. To unsubscribe from this group and stop receiving emails from it, send an email to sqlalchemy+unsubscr...@googlegroups.com. To post to this group, send email to sqlalchemy@googlegroups.com. Visit this group at http://groups.google.com/group/sqlalchemy?hl=en. For more options, visit https://groups.google.com/groups/opt_out.
[sqlalchemy] Two-phase commit from different sessions
Hi everyone! I'm trying to do a two-phase commit using SQLalchemy 0.6.8 with Postgresql 8.3.4, but I think I'm missing something... The workflow goes like this: session = sessionmaker(engine)(autocommit=True) tx = session.connection().begin_twophase(xid) # Doesn't issue any SQL session.begin() # Issues a BEGIN that marks transaction boundary session.add(obj1) session.flush() tx.prepare() then from another session session = sessionmaker(engine)(autocommit=True) session.connection().commit_prepared(xid, recover=True) # recover=True because otherwise it complains that you can't issue a COMMIT PREPARED from inside a transaction This doesn't raise any error, but doesn't write anything to the table either... O_o What am I missing? I tried even blocking the application after the prepare() and issuing a COMMIT PREPARED 'xid' from pgadmin, but still nothing gets written. -- 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: Two-phase commit from different sessions
On Jan 30, 5:02 pm, Michael Bayer mike...@zzzcomputing.com wrote: What's happening above is the session is not in a transaction due to autocommit, so when you call session.connection(), that connection is thrown away as far as the Session is concerned. If you wanted to do it the external way like that, you need to set session.bind = connection, then the Session will do everything in terms of that connection. You could skip the autocommit/begin/flush and just do a single session.commit(), which from the tx point of view would not be the actual commit. Session has a public API for this, though it doesn't at the moment accept the XID, but you can grab the one it generates: session = sessionmaker(engine) session.prepare() session.add(obj1) session.flush() The prepare() should be called _before_ issuing changes to the DB? I thought it was a substitute for the first commit()... Anyway, so after the flush the transaction will be in a prepared state and waiting for the COMMIT PREPARED? I'll try it, thanks :) either way should work, but turning on SQL echo is the best way to see what is/is not happening. Yes I have echo active but it looks like I misunderstood the sequence of commands to give :/ Many thanks for your time! -- 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 refer to a live SA transaction from subsequent requests
An entirely new database connection can resume this transaction by again calling BEGIN PREPARED with the same XID. I'm sorry, but I can't find this command inside the Postgresql docs... Am I missing something? I'm trying to do a multi-request two-phase transaction too, so I thought I could use the xid to refer to the same transaction from every request, but it looks like BEGIN PREPARED doesn't exist, and if I issue a second PREPARE TRANSACTION 'samexid' it complains that the transaction identifier xyz is already in use Thanks in advance! -- You received this message because you are subscribed to the Google Groups sqlalchemy group. To view this discussion on the web visit https://groups.google.com/d/msg/sqlalchemy/-/7UroIxI3UfkJ. 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 refer to a live SA transaction from subsequent requests
So I guess the idea is that each web request does a new PREPARE TRANSACTION with a unique xid, then when the results of all those requests are ready to be committed, the final call then calls COMMIT PREPARED on the full list of xids. I see... Many thanks for your timely explanation :) -- You received this message because you are subscribed to the Google Groups sqlalchemy group. To view this discussion on the web visit https://groups.google.com/d/msg/sqlalchemy/-/B9HdeSaJeb0J. 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] Filtered backref
Hi everyone! Is it possible to have a many-to-one declarative relation between two classes and a _filtered_ backref? I'm trying to build a tagging system for my bloglike application, and to allow a user to apply private tags to posts of other people. My classes are: Owner Post TagAssociation Tag A Post has an Owner, while TagAssociation has a Tag, a Post and an Onwer Between TagAssociation and Post there's a many-to-one, and I'd like to configure a tags backref so that it would handle only the TagAssociations having the same Owner as the Post... Is this possible? Many thanks! -- 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: Strange lazy-load query
On 7 Mar, 15:55, Michael Bayer mike...@zzzcomputing.com wrote: the left outer join means there is a lazy=False or lazy='joinedload' on the relationship, or in this case since its sporadic, the parent Invoice is likely being loaded with an option like joinedload(Product.vat). The options specified in Query get attached to lazy loaders later in the chain, if the given joinedload() chain doesn't start from the entity being queried (which is probably the case if the query uses joinedload() and not joinedload_all()). Problem solved, many thanks :) -- 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] Strange lazy-load query
Hi everyone! I have an object graph like this: Invoice - Detail (one-to-many with cascade) - Product (many-to-one) - VAT (many-to-one) My problem is that sometimes if I have a Detail and try to read its Product, the triggered lazy-loading generates a query more complicated than necessary, having a LEFT OUTER JOIN on the VAT table too... Other times the lazy-loading query joins only Detail and Product. I think I'm doing something fishy here.. What could I check, to ensure that the lazy loading doesn't touch unneeded entities? Many thanks! (SQLAlchemy 0.6.6, PGSQL 8.3) -- 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] DetachedInstanceError on assignment
Hi everyone! I have a client-server application that communicates like this: the client asks for something, the server fetches the data using SQLAlchemy, serializes it and sends it back to the client. Now the client can modify the data and send it back to the server for persistence. It works nicely, but I'm having a little problem.. I'm on the client, with a detached lazy-loaded object having a cascaded one-to-many relation, and I just want to clear this relation, such as: obj.children = [] but it complains that obj is not bound to a Session and that the lazy load operation of attribute 'children' cannot proceed. This used to work with SA 0.5.8, but now we're using 0.6.5... What am I missing? -- 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: Error closing cursor on MySQL silently traps exception
On Jan 22, 7:01 pm, Michael Bayer mike...@zzzcomputing.com wrote:
Assuming the above raises its error just fine as it does on my system, there
must be some unusual pattern in the way the error is being generated. I
don't know that there's anything on the SQLAlchemy side that can address
this kind of thing in a consistent way, usually the strategy is to narrow
down the series of DBAPI calls to a pure MySQL-python script that continues
to reproduce. Its tricky though.
I see... I did a few more tests, and it looks like the problem arises
consistently when executing multiple statements having a syntax error
in the second (or later) one..
Extending your example:
from sqlalchemy import *
e = create_engine('mysql://scott:tiger@localhost/test', echo=True)
e.execute(select * from validtable; this is crap)
This returns a ResultProxy, but on the NEXT execution (even if a
correct one) SQLAlchemy logs a
INFO sqlalchemy.engine.base.Engine.0x...4acL ()
Exception _mysql_exceptions.ProgrammingError: (1064, You have an
error in your SQL syntax; check the manual that corresponds to your
MySQL server version for the right syntax to use near 'this is crap'
at line 1) in bound method Cursor.__del__ of MySQLdb.cursors.Cursor
object at 0xb743238c ignored
Maybe I could persuade SA-migrate to execute one statement at a
time...
Thanks for your assistance :)
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[sqlalchemy] Error closing cursor on MySQL silently traps exception
Hi everyone! I'm building a Pylons webapp using SA 0.6.4 and MySQL-Python 1.2.3. Right now I'm writing the first change script for sqlalchemy-migrate (just 3 lines of SQL). I noticed that if the change script contains some syntax error, SA catches the exception (in pool.py) and logs a Error closing cursor: (1064, You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'NOT NULL' at line 1) and doesn't propagate the exception, so the outer code won't know that something went wrong.. In my case, this means that migrate commits che transaction and I end up with a partially-applied change script. Am I doing something wrong? -- 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: Removing an element from an uncascaded many-to-many
On 17 Nov, 21:41, Michael Bayer mike...@zzzcomputing.com wrote: I'll also make the comment that while the pattern you're illustrating is very unusual (cascade turned off, re-adding detached objects), the ORM is not being consistent in its treatment of non-included child items in mutated collections during flush, in that your append got flushed but the delete doesn't - there's specific code to that effect, which is also not consistent against one-to-many. I've added ticket 1973 which, if it proceeds, would likely be in 0.7. Great, thanks :) -- You received this message because you are subscribed to the Google Groups sqlalchemy group. To post to this group, send email to sqlalch...@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] Removing an element from an uncascaded many-to-many
Hi everyone! I'm puzzled by a behaviour shown by SA 0.6.5 that 0.5.8 didn't show, and I'm wondering what I'm doing wrong.. I have a simple uncascaded many-to-many relationship, and if I try the following: 1) save a child 2) close the session 3) associate the child to a parent and save the parent 4) deassociate the child and save the parent the association doesn't get removed from the junction table.. If I skip closing the session, it DOES get removed... Here's an example: from sqlalchemy import Column, String, Integer, Table, ForeignKey from sqlalchemy.engine import create_engine from sqlalchemy.orm import sessionmaker, relationship from sqlalchemy.ext.declarative import declarative_base Base = declarative_base() junction = Table(junction, Base.metadata, Column(p_id, ForeignKey(parents.id)), Column(c_id, ForeignKey(children.id))) class Child(Base): __tablename__ = children id = Column(Integer, primary_key=True) class Parent(Base): __tablename__ = parents id = Column(Integer, primary_key=True) children = relationship(Child, secondary=junction, cascade=) def save(session, x): session.add(x) session.flush() en = create_engine(sqlite:///:memory:, echo=True) Base.metadata.create_all(en) maker = sessionmaker(en) session = maker(autocommit=True) # Save a child and close the session c = Child() save(session, c) session.close() # Associate the child to a parent and save p = Parent() p.children = [c] save(session, p) # Try to remove the child p.children = [] save(session, p) I'd expect that the last command would log something like BEGIN (implicit) SELECT children.id AS children_id FROM children WHERE children.id = ? (1,) DELETE FROM junction WHERE junction.p_id = ? AND junction.c_id = ? (1, 1) COMMIT SELECT parents.id AS parents_id FROM parents WHERE parents.id = ? (1,) but instead I get only BEGIN (implicit) COMMIT SELECT parents.id AS parents_id FROM parents WHERE parents.id = ? (1,) This used to work with 0.5.8, what am I doing wrong? Many thanks for your attention! -- You received this message because you are subscribed to the Google Groups sqlalchemy group. To post to this group, send email to sqlalch...@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: version_id_col and custom DeclarativeMeta with 0.6
On 15 Nov, 18:57, Michael Bayer mike...@zzzcomputing.com wrote:
First off, I can't reproduce your issue:
Found the culprit: I had a stray 0.5.8 directory lying around, and of
course it was being picked up.. T_T Sorry :(
Second, if you want to switch to newer declarative features, just stick your
__mapper_args__ on Base:
class Base(object):
version = Column(Integer)
@declared_attr
def __mapper_args__(cls):
return {'version_id_col':cls.version}
Base = declarative_base(cls=Base)
Very nice! Thanks :)
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[sqlalchemy] version_id_col and custom DeclarativeMeta with 0.6
Hi everyone!
I'm trying to port my application from SA 0.5.8 to 0.6.5, and I'm
having a problem with __mapper_args__.. :/
The application uses the declarative plugin, and every class derives
from a customized declarative base that aims to add to each one the
version_id_col.
Right now the code is like this:
class MyMeta(DeclarativeMeta):
def __init__(cls, classname, bases, dict_):
cls.version = Column(Integer)
cls.__mapper_args__ = { version_id_col : cls.version }
return DeclarativeMeta.__init__(cls, classname, bases, dict_)
Base = declarative_base(metaclass=MyMeta)
class Entity(Base):
__tablename__ = entities
whatever...
but I think I'm missing something, since even a simple
print Entity().__mapper__.version_id_col
produces a (no name) instead of something like entities.version,
so I'm guessing that some part of SA doesn't see the
version_id_col...?
I understand that SA 0.6 includes a Declarative Mixin feature, but
that would require to touch-up every class declaration to include the
mixin, am I right? It'd be no big deal, but I'd prefer to keep that
complexity away, if it's possible... :)
So my question is: since it was possible with SA 0.5, is there a way
to specify a version_id_col in a custom DeclarativeMeta using 0.6?
Many thanks for your attention!
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[sqlalchemy] Understanding CircularDependencyError
Hi everyone! I'm using the Declarative plugin to generate/handle a DB of about 50 entities, with every kind of relation between them. I've just added a simple one-to-many relation, and now SA is complaining that: sqlalchemy.exc.CircularDependencyError: Circular dependency detected [(base_files, aut_trasporto), (base_files, aut_stoccaggio), (aut_stoccaggio, jun_cer_abilitati_aut_stoccaggi), (aut_stoccaggio, conf), (aut_stoccaggio, formulari), (targhe, jun_cer_abilitati_targhe), (targhe, formulari), (formulari_dett, fatture_dett), (formulari_dett, ddt_dett), (aut_trasporto, formulari), (aut_trasporto, conf), (aut_trasporto, targhe), (ddt_dett, fatture_dett), (formulari, formulari_dett), (formulari, base_files)][] But I can't understand how the circle comes into play, since the new triggering relation has as many side an entity with just plain attributes (Unicode/Integer/DateTime).. So my question: what is the list of table names that follows CircularDependencyError? Should I use it to find out where the circular dependency is? Thanks for your time! --~--~-~--~~~---~--~~ 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: Understanding CircularDependencyError
It looks like I should tinker with the use_alter parameter.. :) --~--~-~--~~~---~--~~ 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: Shallow copying
On 23 Ott, 19:19, Mike Conley mconl...@gmail.com wrote: I'm trying to automatically build a shallow copy of a SA-mapped object.. At the moment my function is just: newobj = src.__class__() for prop in class_mapper(src.__class__).iterate_properties: setattr(newobj, prop.key, getattr(src, prop.key)) but I'm having troubles with lazy relations... Obviously getattr triggers the lazy loading, but since I don't need their values right away, I'd like to just copy the this should be lazy loaded-state of the attribute... Is this possible? I did something similar. I iterated on class_mapper().columns to get the attributes to populate. That approach skipped all the relations, and in my case was exactly what I wanted I see, but I need a proper shallow copy instead, with every attribute.. Is there no way? :/ --~--~-~--~~~---~--~~ 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: Shallow copying
On 26 Ott, 13:41, Mike Conley mconl...@gmail.com wrote: I see, but I need a proper shallow copy instead, with every attribute.. Is there no way? :/ What is missed? I am not sure what you mean by shallow copy. The fact that there are relations to be lazy loaded is present in the new object when instantiated. Obviously the objects pointed to by the relation are not copied, but I would call that a deep copy, and to do that you would need to iterate over them also. I'm sorry, by shallow copy I mean that only the parent object should be a copy (=different instance), while the related ones should be kept as-is... For example, given an object A that references B and C, a shallow copy of A would be made up of a copy of A that references the original B and C (not copies of B or C). So, in Python a non-automatic shallow copy would be: A = Some_class() A.refs = [B, C] Acopy = Some_class() Acopy.refs = A.refs My problem is that if A.refs has to be lazy loaded, when I try to copy it over to Acopy, it triggers the query, and I'd like to avoid that, while still copying the fact that Acopy.refs should be the same as A.refs. Thanks for your attention 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 sqlalchemy+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/sqlalchemy?hl=en -~--~~~~--~~--~--~---
[sqlalchemy] Re: Shallow copying
On 26 Ott, 15:29, Mike Conley mconl...@gmail.com wrote: So, in Python a non-automatic shallow copy would be: A = Some_class() A.refs = [B, C] Acopy = Some_class() Acopy.refs = A.refs My problem is that if A.refs has to be lazy loaded, when I try to copy it over to Acopy, it triggers the query, and I'd like to avoid that, while still copying the fact that Acopy.refs should be the same as A.refs. So, let's understand the underlying data model. We say, A is a parent object related to B and C children. (1) If this is a one-to-many relationship, then B and C will contain foreign keys pointing at A. Copying of A to Acopy cannot have references point at [B, C] because the children cannot point at two parents at the same time; there is only one foreign key column. (2) If this is a many-to-many relationship, then there will be another table between A and [B,C] managing the many-to-many connection and something needs to be done during the copy to preserve the relationships. Which do we have here? Ehr.. Both :) I'm looking for a generic way to build a shallow copy, so the relations could be of any type. Anyway, now that you point it out I'm thinking that maybe there's no way to just copy the informations that would allow SQLA to perform the lazy loading from the new instance, since this instance would have no ID at all, and SQLA couldn't possibly match it with related data.. Maybe that could have worked with Hibernate, since it uses Proxy objects to implement lazy loading.. Many thanks for your assistance! :) --~--~-~--~~~---~--~~ 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: UniqueConstraint with a function
In the end I followed the suggestion at http://stackoverflow.com/questions/1510018/compound-uniqueconstraint-with-a-function Many thanks for chiming in all the same :) --~--~-~--~~~---~--~~ 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] UniqueConstraint with a function
Hi everyone! I have a class Document with attributes Number and Date, is there a way to set a UniqueConstraint on Number + year(Date)? (SQLAlchemy 0.5.5, PostgreSQL 8.3.4) Thanks in advance! --~--~-~--~~~---~--~~ 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: UniqueConstraint with a function
On 2 Ott, 10:42, Joril jor...@gmail.com wrote: I have a class Document with attributes Number and Date, is there a way to set a UniqueConstraint on Number + year(Date)? Self-followup: should I use a unique Index instead? But how do you create a functional index in SQLAlchemy? --~--~-~--~~~---~--~~ 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] Auto-incrementing attribute with custom logic
Hi everyone! I have a simple Invoices class with a Number attribute that has to be filled in by the application when the user saves an invoice. There are some constraints: 1) the application is a (thin) client-server one, so whatever determines the number must look out for collisions 2) Invoices has a version attribute too, so I can't use a simple DBMS-level autoincrementing field I'm trying to build this using a custom Type that would kick in every time an invoice gets saved. Whenever process_bind_param is called with a None value, it will call a singleton of some sort to determine the number and avoid collisions. Is this a decent solution? Anyway, I'm having a problem.. Here's my custom Type: class AutoIncrement(types.TypeDecorator): impl = types.Unicode def copy(self): return AutoIncrement() def process_bind_param(self, value, dialect): if not value: # Must find next autoincrement value value = 1 # Test value :) return value My problem right now is that when I save an Invoice and AutoIncrement sets 1 as value for its number, the Invoice instance *doesn't* get updated with the new number.. Is this expected? Am I missing something? Many thanks for your time! (SQLA 0.5.3 on Python 2.6, using postgreSQL 8.3) --~--~-~--~~~---~--~~ 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: Auto-incrementing attribute with custom logic
On 24 Giu, 16:28, Michael Bayer mike...@zzzcomputing.com wrote: whats the second question ? is this expected? yes. TypeEngine objects don't have anything to do with default value generation. I see, thanks! --~--~-~--~~~---~--~~ 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: Automatic eager loading
On 19 Mag, 01:03, Michael Bayer mike...@zzzcomputing.com wrote: you'd have to roll that yourself. Its generally not feasable for every relation on an object to be eagerloaded since it would create too many joins. I see, I'll just choose eager loads manually depending on context then, thanks for your time! --~--~-~--~~~---~--~~ 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] SQLAlchemy-announce RSS
Hi everyone, I'm sorry, is there an RSS feed somewhere with just the announcements of SA's new releases? Thanks! --~--~-~--~~~---~--~~ 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] Query with outer join and function
Hi everyone! I'm trying to concoct a somewhat complicated query via Query API.. The situation is the following: - A many-to-one relation between classes C and D - Class C has an attribute value My objective is to retrieve the ids of a left outer join between D and C (so, all the Ds and eventually the related Cs) where C.value has the maximum value, given the same D. So for example, given a table D made of [id, otherfield] (1, A) (2, B) (3, C) and a table C made of [id, d_id, value] (1, 1, 0) (2, 1, 1) - max value for d_id 1 (3, 2, 3) - max value for d_id 2 (4, 2, 2) I'd like my query to return [d.id, c.id] (1, 2) (2, 3) (3, None) Is this possible with a single query? Many thanks for your time! --~--~-~--~~~---~--~~ 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: Query with outer join and function
On 10 Apr, 12:52, a...@svilendobrev.com wrote: that's what i have in bitemporal queries. u need a groupby and subquery/ies. I see, thanks for your hint! I tried to do it with bare SQL via pgadmin, and I ended up with select d.id, c.id from d left outer join ( select c.* from c join ( select d_id, max(value) as v from c group by d_id) as sub on c.d_id = sub.d_id and c.value = sub.v) as c on c.d_id = d.id Now I'll try with the Query API :) But I was wondering, maybe there's a simpler way than 3 nested queries...? --~--~-~--~~~---~--~~ 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: Query with outer join and function
On 10 Apr, 15:43, Mike Conley mconl...@gmail.com wrote:
Try this, has one nested query
sub = session.query(C.id.label('c_id'),
C.d_id.label('d_id'),
func.max(C.value).label('c_maxvalue')
).group_by(C.d_id).subquery()
I tried something like that earlier, but postgreSQL complained that
column c.id must appear in the GROUP BY clause or be used in an aggregate
function
I think this is because given N rows with the same d_id, the DBMS
can't figure out which C.id to return, even if I'd like it to choose
the one corresponding to the current maxvalue :/
Or maybe I'm missing something?
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[sqlalchemy] Re: Query with outer join and function
On 10 Apr, 15:54, Mike Conley mconl...@gmail.com wrote: This will teach me to run a test it first, I don't think this is exactly right, but it should be close. That's ok all the same, thanks for taking the time for posting :) Anyway my current implementation via Query API is sub = s.query(C.d_id, func.max(C.value).label(v)).group_by (C.d_id).subquery() sub2 = s.query(C).join((sub, and_(C.d_id==sub.c.d_id, C.value==sub.c.v))).subquery() q = s.query(D, sub2.c.id).outerjoin(sub2) so the result is instances of D along the (eventually) related C.id.. Now let's see if I can fetch complete instances of C instead of just the id X-) --~--~-~--~~~---~--~~ 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: Query with outer join and function
On 10 Apr, 16:24, Joril jor...@gmail.com wrote: Now let's see if I can fetch complete instances of C instead of just the id X-) For the record, my final implementation: sub = s.query(C.d_id, func.max(C.value).label(v)). group_by(C.d_id).subquery() sub2 = s.query(C).join((sub, and_(C.d_id==sub.c.d_id, C.value==sub.c.v))).subquery() idmap = s.query(D.id.label(did), sub2.c.id.label(cid)). outerjoin(sub2).subquery() q = s.query(D, C).join((idmap, idmap.c.did==D.id)). outerjoin((C, idmap.c.cid==C.id)) Yields complete instances of D and C, having maximum C.value where relevant :) I must say that SQLAlchemy keeps amazing me.. Many thanks to everyone! --~--~-~--~~~---~--~~ 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: Getting relation orphans
On 26 Mar, 18:02, Michael Bayer mike...@zzzcomputing.com wrote: you can check if an object is an orphan related to a certain relation() its supposed to belong to, though there's no automated way to go from that object to the actual collection it was removed from unless you scan through all the potential parents in the session and check each one. the current way to check for an orphan is and internal thing at the moment, and looks like: some_relation.mapper._is_orphan(attributes.instance_state(item)) I see, thanks :) --~--~-~--~~~---~--~~ 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] Sorting by related property
Hi everyone! I have a simple many-to-one relation between class A and class B, and I'd like to use a Query to get the A instances sorted by a B attribute (e.g. code).. I tried with something like this: q = session.query(A) q.order_by(A.list_of_b.code) but obviously list_of_b doesn't know about codes.. How should I do it? Many thanks! (SQLA 0.5.2) --~--~-~--~~~---~--~~ 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: Sorting by related property
On 19 Mar, 15:09, Martin mar...@chinasoftinc.com wrote:
I guess
q = session.query(A).join('b').order_by(B.code).all()
should do the trick, at least it did under 0.4.8
It works in 0.5.2 too, thanks :)
I was wondering though, maybe 0.5.x has a way to do it without the
join? I mean, SQLA should have all the informations to figure it out
by itself, I think..?
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[sqlalchemy] Re: Database migrations using declarative
On 5 Mar, 18:40, Michael Bayer mike...@zzzcomputing.com wrote: im finding it easiest to just autoload the tables in my migrate script. That way there's no cut and paste the table def going on, you just load them as they are from the DB. and the schema definition stays in the database for those who get bent out of shape about that. problem solved. the migrate docs should suggest this too. I see, thanks for your help :) (And Kevin's too of course) --~--~-~--~~~---~--~~ 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] Database migrations using declarative
Hi everyone! I'm looking for a way to handle database migrations/upgrades and found projects such as sqlalchemy-migrate and mikuru.. My understanding is that those projects expect the model to be in NON-declarative form, that is, with users_table = Table(...) and the like.. But what if my program uses exclusively declarative? Can I use them all the same? Or are there tools that work with declarative, or should I roll my own? Many thanks for your time! --~--~-~--~~~---~--~~ 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] Infinite recursion trying to deserialize any restriction
Hi everyone! I have a simple one-to-many relation between two classes, and I'm trying to serialize/deserialize an any restriction on them.. My problem is that deserialization fails with maximum recursion depth exceeded. Am I doing something wrong? Here's my testcase: from sqlalchemy import Column, Integer, String, ForeignKey from sqlalchemy.ext import serializer from sqlalchemy.orm import relation from sqlalchemy.ext.declarative import declarative_base # Tables definition Base = declarative_base() class Child(Base): __tablename__ = 'child' id = Column(Integer, primary_key=True) parent_id = Column(Integer, ForeignKey(parent.id)) data = Column(String) class Parent(Base): __tablename__ = 'parent' id = Column(Integer, primary_key=True) children = relation(Child) # Build any restriction r = Parent.children.any(Child.data==x) # Serialize and deserialize it ser = serializer.dumps(r) serializer.loads(ser, Base.metadata) Thanks for your time! (tried with SQLA 0.5.0 and 0.5.2, Python 2.5.2) --~--~-~--~~~---~--~~ 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: Abstract base class
Michael Bayer wrote: meta = MetaData() Base1 = declarative_base(metadata=meta, metaclass=MyMetaClass) Base2 = declarative_base(metadata=meta, metaclass=MyOtherMetaClass) Base2._decl_class_registry = Base1._decl_class_registry Great! So now I have a MetaClass2 that extends MetaClass1, and they share a set of fields.. Works perfectly :) Another question if I may.. What would be the recommended way to identify a mapped object now? I mean, I could use something like isinstance(obj, Base1) or isinstance(obj, Base2) but is there a more concise way? It looks like Base1 and Base2 extend object directly.. This is a use case we can make easier in a future release. That'd be appreciated, surely :) Many thanks for your time, as always! --~--~-~--~~~---~--~~ 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: Abstract base class
Michael Bayer wrote(): isinstance(obj, (Base1, Base2)), or you could make yet another Base class below Base1 and Base2 and specify it as cls to declarative_base(). I see.. Thanks again, you are very helpful! --~--~-~--~~~---~--~~ 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: Mapping an array of strings?
Michael Bayer ha scritto: hibernate-style custom types are documented here: http://www.sqlalchemy.org/docs/05/reference/sqlalchemy/types.html?highlight=typeengine#custom-types or you can use PickleType. Perfect, many thanks! --~--~-~--~~~---~--~~ 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] Mapping an array of strings?
Hi everyone! Is there a way to (declaratively) map a class so that one of its members is an array of strings? (As an example use-case, a User class with an array of her websites) With Hibernate I'd just register a custom persister that would serialize the array/list to a big varchar field, is there a way to do this with SQLA? Many thanks! --~--~-~--~~~---~--~~ 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] Pickling a restriction
Hi everyone! Is there a way to pickle a Query restriction? If I try this: import cPickle restr = (MyDataClass.intproperty==1) cPickle.dumps(restr, 1) I get a cPickle.PicklingError: Can't pickle class 'sqlalchemy.orm.properties.ColumnComparator': attribute lookup sqlalchemy.orm.properties.ColumnComparator failed Many thanks for your time! --~--~-~--~~~---~--~~ 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: Pickling a restriction
Michael Bayer ha scritto: There's a new extension in 0.5 which allows pickling of any ORM structure called sqlalchemy.ext.serializer. I see, thanks :) Although the error below shouldn't occur in any case, try out the latest trunk. Do you mean normal Pickle shouldn't raise the PicklingError in my case? I tried with a simpler test: from sqlalchemy.ext.declarative import declarative_base from sqlalchemy import Column, Integer import cPickle Base = declarative_base() class Test(Base): __tablename__ = 'test' id = Column(Integer, primary_key=True) restr = Test.id==1 cPickle.dumps(restr,1) but it throws the same error (I'm using 0.5rc4, but I tried rev 5457 too) --~--~-~--~~~---~--~~ 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: Data logging and many-to-many's
Quite complicated, I see X-) Anyway, I've been able to implement the clean way you suggested (or at least the test suite says so :) ).. Many thanks again for your time, you've been very helpful! (Thanks to Svil too for your contribution!) --~--~-~--~~~---~--~~ 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: Data logging and many-to-many's
On 19 Nov, 16:28, Michael Bayer [EMAIL PROTECTED] wrote: a guaranteed stable way that doesn't rely on SQLAlchemy implementation details and is easy to understand is here. this is how I would do it: http://pastebin.com/f6670eebe I see, many thanks for yor time :) Out of curiosity, is there a solution that wouldn't require creating new instances of the objects? (Some magic incantation like the del instance_state(entity).key you suggested me some time ago, I guess..?) --~--~-~--~~~---~--~~ 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: Data logging and many-to-many's
On 19 Nov, 17:22, Michael Bayer [EMAIL PROTECTED] wrote: Out of curiosity, is there a solution that wouldn't require creating new instances of the objects? (Some magic incantation like the del instance_state(entity).key you suggested me some time ago, I guess..?) not really since you'd have to manually recreate the history attributes for the children list in order for SQLA to see those items as newly added, thus resulting in the rules that establish the association to be invoked. I see.. But - sorry if I insist - are you implying that it would be too difficult to do? I know it'd be a kind of ugly hack, but since I spent almost the whole day looking for it, now I'm wondering if I was looking for something that doesn't exist at all X-) since the path of create and associate objects like normal python objects is the path of usage the ORM was designed for, that's the one that will work without danger of being impacted by implementation details. Yes of course.. Thanks 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: Filtering a primaryjoin
On 5 Nov, 18:17, Joril [EMAIL PROTECTED] wrote: I'd like to add a filter to a relation, so that it ignores records of the remote table if they're flagged as logically_deleted (a boolean field of the child table) Solved, children = relation(Child, primaryjoin=and_(id == Child.parent_id, Child.logically_deleted==False)) Thanks anyway! --~--~-~--~~~---~--~~ 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] How to know if a lazy relation isn't loaded yet?
Hi everyone! I tried googling but found nothing.. Is there a way to know beforehand whether a relation would be lazy-loaded? For example, given a lazy parent-children relation and an instance X of parent, I'd like to know if X.children is already loaded, without triggering the query. Thanks in advance! --~--~-~--~~~---~--~~ 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: Documentation on declarative relations
Lawrence Oluyede ha scritto: Have a look here: http://www.sqlalchemy.org/docs/05/plugins.html#plugins_declarative Didn't think of looking at the plugins section at all X-) Thanks! --~--~-~--~~~---~--~~ 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] Documentation on declarative relations
Hi everyone! I'm sorry, I can't find documentation on how to specify relations using the declarative syntax.. Could someone provide a pointer? Thanks for your time! --~--~-~--~~~---~--~~ 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] Query representation
Hi everyone! I'm looking for a way to log queries at a higher level than SQL.. That is, given the class Base = declarative_base() class DataTest(Base): id = Column(Integer, primary_key = True) propb = Column(Boolean) __tablename__ = t right now when I try to print a query restriction: restr=(DataTest.propb==False) print restr I get something like t.propb = :propb_1 Is there a way to get propb = False ? I know I can fetch the operands via restr.left.name and restr.right.value, but what about the operator? Many thanks for your help! --~--~-~--~~~---~--~~ 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] Data logging
Hi everyone! I'm trying to implement data logging with SQLAlchemy.. That is, whenever someone updates a persisted entity, generate a new record and then mark the old one as such. My problem right now is that if I load an entity from the DBMS, modify it and then try to save it again, I have to tell SQLA that the entity needs to be INSERTed, not UPDATEd.. I tried zeroing entity.id and entity.version, but it still tries an UPDATE.. How do I trick SQLA into thinking it's a new entity? Many thanks for your time! --~--~-~--~~~---~--~~ 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: Data logging
Perfect! Thanks 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: Query representation
On 6 Ott, 16:26, Michael Bayer [EMAIL PROTECTED] wrote: Alternatively you could visit and compile the clause directly with your own compiler, which subclasses compiler.DefaultCompiler and overrides visit_bindparam() to return a string representation of the data instead of a param name. I found a solution using compiler.operator_string(), but yours looks much nicer.. I'll try it, thanks 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] Losing object state after rollback
Hi everyone!
I'm sorry, I'm using SQLA 0.5rc1 with autocommit=True, and I'm having
a problem with rollbacks.. It looks to me that whenever I try to save
an object that triggers some kind of exception (thus triggering a
rollback) I lose that object's previous state..
To elaborate, here's a simple testcase:
from sqlalchemy import Column, String, Integer
from sqlalchemy.engine import create_engine
from sqlalchemy.orm import sessionmaker
from sqlalchemy.ext.declarative import declarative_base
Base = declarative_base()
class DataTest(Base):
Simple class with versioning
id = Column(Integer, primary_key = True)
propstring = Column(String)
version = Column(Integer)
__tablename__ = t
__mapper_args__ = { version_id_col : version }
def save(session, x):
Save x with begin/commit
session.begin()
session.add(x)
session.commit()
en=create_engine(sqlite:///:memory:, echo=True)
Base.metadata.create_all(en)
maker = sessionmaker(en)
session = maker(autocommit=True)
# Save a DataTest...
x=DataTest()
x.propstring = test
save(session, x)
# ...then simulate a concurrent modification
x.version=0
try:
save(session, x)
except:
session.rollback()
# I'd expect x.version to be the way it was
assert x.version == 0
Am I misunderstanding something? Is there a way to keep x the way it
was before the save() ?
Many thanks for your attention!
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[sqlalchemy] Declarative and common fields
Hi everyone! I'm new to SQLAlchemy and I'm using version 0.5rc1.. I need every entity class to have a few common fields, so I tried writing an abstract base class, declarative-style, that every other entity class would subclass. So for example: --- from sqlalchemy.ext.declarative import declarative_base from sqlalchemy import Column, String, DateTime, Integer ORMBase = declarative_base() class BaseObject(ORMBase): id = Column(Integer, primary_key=True) creation_time = Column(DateTime) modify_time = Column(DateTime) class TestEntity(BaseObject): value = Column(String) --- But SQLAlchemy complains that sqlalchemy.exc.ArgumentError: Mapper 'Mapper|BaseObject|None' does not have a mapped_table specified. (Are you using the return value of table.create()? It no longer has a return value.) Is there a way to tell SQLAlchemy to treat BaseObject like a non- mapped-class? I tried using ORMBase as mixin to TestEntity (so BaseObject extends object and TestEntity extends BaseObject and ORMBase), but now I get a sqlalchemy.exc.ArgumentError: Mapper Mapper|TestEntity|tests could not assemble any primary key columns for mapped table 'tests' so I guess that maybe I'm going down the wrong road.. Am I doing something that Declarative doesn't like? :) Should I try Elixir instead? Many thanks for your time! --~--~-~--~~~---~--~~ 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: Declarative and common fields
I don't know whether this is currently possible with Declarative or not. In the case it isn't, patching Declarative should be quite easy (but I don't know if such a patch would be accepted or not). I see.. I'll wait a bit then, maybe one of the developers will tell us if it'd be acceptable :) If you don't want to go down that route, Elixir does support that pattern. Do you mean these http://elixir.ematia.de/trac/wiki/FAQ#HowdoIaddfunctionalitytoallmyentitiestothebaseclass http://elixir.ematia.de/trac/wiki/FAQ#HowdoIprovideadifferentbaseclassthanEntity ? The comment Note that in this case you'll lose all default methods provided by the Entity class makes me think that extending Entity isn't supported even in Elixir, have I got it wrong? Thanks 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] Optimistic locking
Hi everyone! I'm sorry, I tried the documentation but couldn't find this piece of information.. How do I implement optimistic locking with SA? I mean, is there a framework for versioning fields? (The way Hibernate does) Should I do it by hand? Many thanks for your attention! --~--~-~--~~~---~--~~ 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: Optimistic locking
Oops, found version_id_col at http://www.sqlalchemy.org/docs/adv_datamapping.html, sorry! --~--~-~--~~~---~--~~ 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 -~--~~~~--~~--~--~---
