you're running 0.5.0rc2, an early release candidate of 0.5. There have been five bugfix releases since then, have you tried running on the latest release ?
On Jan 26, 2009, at 12:59 PM, Toby Bradshaw wrote: > > Ok.. given: > > CREATE TABLE example_a > ( > id integer NOT NULL, > time_units integer, > CONSTRAINT example_a_pkey PRIMARY KEY (id) > ) > > and (based on > http://www.sqlalchemy.org/docs/05/mappers.html#using-descriptors): > > from sqlalchemy import * > from sqlalchemy.orm import sessionmaker, mapper, synonym > > class A(object): > def _set_t(self, t): > print "SET" > self.timeunits = t / float(10) > def _get_t(self): > print "GET" > return self.timeunits * 10 > time_units = property(_get_t, _set_t) > > engine = create_engine("postgres://tobe:<snip>@localhost/test") > engine.echo = False > > session_class = sessionmaker( > bind = engine, autoflush = True, autocommit = False, > ) > > meta = MetaData(bind = engine) > table_A = Table("example_a", meta, autoload = True) > > print A.time_units > mapper(A, table_A, properties = { > "time_units" : synonym("timeunits", map_column = True) > }) > > session = session_class() > > a = session.query(A).all()[0] > print a.timeunits > a.timeunits = 1 > print a.timeunits > print A.timeunits > print A.time_units > ~ > > ~ > > > > Running the above: > > t...@bismuth:~/src/tobe/bdp_webif$ python test.py > <property object at 0x849a7fc> > 10 > 1 > <Mapper at 0x84f030c; A>.timeunits > Traceback (most recent call last): > File "test.py", line 36, in <module> > print A.time_units > File > "/usr/lib/python2.5/site-packages/SQLAlchemy-0.5.0rc2-py2.5.egg/ > sqlalchemy/orm/attributes.py", > line 121, in __str__ > return repr(self.parententity) + "." + self.property.key > File > "/usr/lib/python2.5/site-packages/SQLAlchemy-0.5.0rc2-py2.5.egg/ > sqlalchemy/orm/attributes.py", > line 184, in __getattr__ > return getattr(descriptor, attribute) > AttributeError: 'property' object has no attribute 'parententity' > > > So you can clearly see that the get and set are not called when > accessing timeunits. They *are* called when accessing time_units (not > shown). If you substitute '_email' for 'timeunits' and 'email' for > 'time_units' then I believe this is an identical pattern to that shown > in the documentation on > this:http://www.sqlalchemy.org/docs/05/mappers.html#using-descriptors. > The same behaviour is observed if I try an example with manually > specified columns. > > So.. again.. am I simply not getting something here, is the example > misleading or wrong or is the code broke in some way. > > Thanks in advance, > > -- > Toby Bradshaw > Ideaworks 3d Ltd, > London, UK. > > Michael Bayer wrote: >> On Jan 23, 2009, at 1:43 PM, Toby Bradshaw wrote: >> >> the synonym() construct and the mapped attribute it creates >> represents >> a proxy to the mapped column only in the context of accessing and >> setting values within the python application space. It is not >> invoked >> when the database populates the value of the mapped column itself. >> the general idea of synonym is that the column-based information >> stays >> represented on the mapped instance in the identical manner that it >> does within the database, and the synonym-based attribute interprets >> application-level values into the column representation. >> >> it should definitely be invoked when setting the property of an >> existing instance of B, so if that's not working you can share with >> us >> exactly how you are configuring things, since you might be missing >> some detail. >> >>> >> > > > --~--~---------~--~----~------------~-------~--~----~ 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 -~----------~----~----~----~------~----~------~--~---
