the label is always "tablename_columnname". youd have to show me
where you need that to be "programmatic".
On Feb 27, 2007, at 2:29 PM, Dennis wrote:
>
> Thanks for taking a peek.
>
> Interesting, it does indeed fix the issue to use labels. Now I have
> another issue though, I have a case statement in my select which I was
> specifying like this:
>
> select ( ['case when .... yada yada yada end as something' ] ......
>
> If use_labels = True, then the query breaks because the generated sql
> has two as label parts two it.
>
> if I delete the "as something" part, I think don't know
> programatically what the label is though. I need to know that because
> I order by it.
>
> Isn't there a way to find out a column label from a query?
>
> -Dennis
>
> On Feb 27, 12:47 pm, Michael Bayer <[EMAIL PROTECTED]> wrote:
>> if you run it with full blown logging on, i.e.:
>>
>> import logging
>> logging.basicConfig()
>> logging.getLogger('sqlalchemy.engine').setLevel(logging.DEBUG)
>> logging.getLogger('sqlalchemy.orm').setLevel(logging.DEBUG)
>>
>> the issue can be detected when you look at the mapper creating
>> instance keys for "T" (although this is clearly not a novice issue):
>>
>> DEBUG:sqlalchemy.orm.mapper.Mapper:(T|ts) _instance(): identity key
>> (<class '__main__.T'>, (1,), None) not in session[]
>> DEBUG:sqlalchemy.orm.mapper.Mapper:(T|ts) _instance(): identity key
>> (<class '__main__.T'>, (None,), None) not in session[]
>> DEBUG:sqlalchemy.orm.mapper.Mapper:(T|ts) _instance(): identity key
>> (<class '__main__.T'>, (3,), None) not in session[]
>> DEBUG:sqlalchemy.orm.mapper.Mapper:(T|ts) _instance(): identity key
>> (<class '__main__.T'>, (None,), None) not in session[]
>> DEBUG:sqlalchemy.orm.mapper.Mapper:(T|ts) _instance(): identity key
>> (<class '__main__.T'>, (5,), None) not in session[]
>>
>> so its not getting an identity key for every other row, which
>> indicates its looking at the wrong column in the result set. (on
>> each of those "None"s, its going to skip that entity) looking at the
>> query:
>>
>> SELECT ts.id, ts.dat, other.ts_id, other.other_dat
>> FROM ts LEFT OUTER JOIN other ON ts.id = other.ts_id
>>
>> we can see that "other" has a column called "ts_id", which looks
>> exactly like the label that would be made for "id" in table "ts". so
>> thats whats happening here. so throwing on a "use_labels=True" to
>> the query (or changing the name of "ts_id") produces the query:
>>
>> SELECT ts.id AS ts_id, ts.dat AS ts_dat, other.ts_id AS other_ts_id,
>> other.other_dat AS other_other_dat
>> FROM ts LEFT OUTER JOIN other ON ts.id = other.ts_id
>>
>> that gives the correct results.
>>
>> not sure what SA can really do here to make this kind of issue easier
>> to catch, since the resultproxy itself is where its looking for "col
>> label, col name, ", etc. the generated labels are generally more
>> accurate. i tried playing around with ResultProxy to make it detect
>> an ambiguity of this nature, but i think it might not be possible
>> unless more flags/switches get passed from the statement to the
>> result (which id rather not do since it further marginalizes straight
>> textual queries), since if the select statement uses table/col labels
>> for each column, there still could be conflicts which dont matter,
>> such as the column names the normal eager loader generates:
>>
>> 'ts_id', 'ts_dat', 'other_4966_ts_id', 'other_4966_other_dat',
>>
>> that result is from column "ts_id" attached to an Alias
>> "other_4966". if we said "dont allow any Column to be found twice in
>> the row", then that breaks (since it will match other_4966_ts_id on
>> its _label, ts_id on its name).
>>
>> On Feb 27, 2007, at 12:09 PM, Dennis Muhlestein wrote:
>>
>>> from sqlalchemy import *
>>
>>> e=create_engine('sqlite://memory')
>>> ts=Table('ts',e,
>>> Column ( 'id',Integer,primary_key=True),
>>> Column ( 'dat',Integer,nullable=False))
>>> ts.create()
>>
>>> to_oneornone=Table('other',e,
>>> Column ( 'ts_id', Integer,ForeignKey('ts.id'), primary_key=True,
>>> nullable=False ),
>>> Column ( 'other_dat', Integer, nullable=False ) )
>>> to_oneornone.create()
>>
>>> class T(object): pass
>>> T.mapper=mapper(T,ts)
>>
>>> class To(object):pass
>>> To.mapper=mapper(To,to_oneornone,properties={'ts':relation
>>> (T,backref=backref('other',uselist=False))})
>>
>>> s=create_session()
>>> for x in range(10):
>>> t=T()
>>> t.dat=x
>>> s.save(t)
>>
>>> if x % 2 == 0: # test every other T has an optional data
>>> o=To()
>>> o.other_dat=x
>>> t.other=o
>>
>>> s.save(t)
>>> s.flush()
>>
>>> s.clear()
>>
>>> somedata=s.query(T).options(eagerload('other')).select()
>>> print 'Number results should be 10: ', len(somedata)
>>
>>> s.clear()
>>
>>> sel=select([ts,to_oneornone],
>>> from_obj=[ts.outerjoin(to_oneornone)])
>>
>>> print "Raw select also is 10: " , len(sel.execute().fetchall() )
>>
>>> print "Instances should also be 10: ", len(s.query(T).options
>>> (contains_eager('other')).instances(sel.execute()))
>
>
> >
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