Update test program in the atachment. No I don't agree that this is a fixed bug.
Take an example. You got a mapper, and you want just one row, but you dont't
know or don't care how to construct a query that only yields one row (not a
very unlikely scenario I might add, actually, quite a common one).
With selectone out of question since it raises an exception when having a
result-set of two, how do you get just one object from a mapper?
Quoting Florian Boesch <[EMAIL PROTECTED]>:
> I'm sorry I don't quite get it. There's two different issues at hand.
>
> #1 No result of selectone was forthcomming.
> things todo: either return None or Raise an exception (a more sensible one
> please), consensus over what to do will have to ensue.
> My vote on this goes with None as it can-be quite an expected result not to
> get
> something from selectone, wheras I see exceptions more of a way to signify
> problems that indicate contractial missbehavior.
>
> #2 How can selectone return more then one? I mean, selectone *is* the
> contract...
>
> Quoting Robert Leftwich <[EMAIL PROTECTED]>:
>
> > Florian Boesch wrote:
> > > selectone of a mapper does not work anymore.
> > >
> >
> > I think you'll find it is still working, it is just throwing an exception
> > when 0
> > *or* > 1 rows are returned, i.e. add one f = Foo() and an
> > objectstore.commit()
> > and the exception goes away, add a second g = Foo() and the exception is
> > thrown
> > again as more than 1 row has been returned.
> >
> > When I saw this over the weekend my first reaction was to think it was a
> > problem, but the function is called selectone and the new behaviour does
> meet
> > that contract, i.e give me one and only one row. However, there is now no
> way
> > to
> > tell if the error was thrown because there were no rows or more than one
> row,
> > which is often a useful piece of information :-).
> >
> > So, what do people think- should the current behaviour remain or should it
> be
> > changed? If the latter should it revert to the original behaviour, return
> > None
> > when no rows are returned and throw the exception if > 1 are returned or
> > something else?
> >
> > Robert
> >
> >
> >
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from sqlalchemy import *
engine = create_engine('oracle://dsn=orcl&user=test&password=test')
foo = Table('foo', engine, Column('id', Integer, Sequence('foo_seq'),
primary_key=True))
class Foo(object): pass
foos = mapper(Foo, foo)
try: foo.drop()
except: pass
try: foo.create()
except: pass
foos.selectone() # should raise a more sensible exception or return None
foo.insert().execute()
foos.selectone() # ok
foo.insert().execute()
foos.selectone() # eh.. *one* is my understanding of contract...
'''
File "selectone.py", line 13, in ?
foos.selectone()
File
"/usr/local/lib/python2.4/site-packages/SQLAlchemy-0.1.4-py2.4.egg/sqlalchemy/mapping/mapper.py",
line 496, in selectone
raise InvalidRequestError('Multiple rows returned for selectone')
sqlalchemy.exceptions.InvalidRequestError: Multiple rows returned for selectone
'''
