using explicit labels is the best approach to bypass SQLA's labeling schemes,
such as this example:
from sqlalchemy import *
from sqlalchemy.orm import *
from sqlalchemy.ext.declarative import declarative_base
Base = declarative_base()
class A(Base):
__tablename__ = 'a'
id = Column(Integer, primary_key=True)
x = Column(Integer)
y = Column(Integer)
e = create_engine("sqlite://", echo=True)
Base.metadata.create_all(e)
sess = Session(e)
sess.add_all([
A(x=1, y=2),
A(x=2, y=5),
A(x=3, y=3),
])
sess.commit()
stmt = select([A.id, A.x, A.y, (A.x + A.y).label('xplusy')])
print sess.query(A, stmt.c.xplusy).from_statement(stmt).all()
On Apr 25, 2013, at 12:47 PM, Richard Gerd Kuesters <rich...@humantech.com.br>
wrote:
> Yeah, well, it is a select but didn't work. I also made another select on top
> of it (to be sure), but the "error" persists (could not locate column ...).
>
> Nevermind about it, I think it's not a question of good usage of SA I think :)
>
> Thanks for your help!
>
> Cheers,
> Richard.
>
>
> On 04/25/2013 01:22 PM, Michael Bayer wrote:
>> if the original "q" is a select(), this should work:
>>
>> query(MyClass, q.c.somecol, q.c.someothercol).from_statement(q)
>>
>> if not then I guess I'll screw around with it to see what works.
>>
>>
>>
>> On Apr 25, 2013, at 10:37 AM, Richard Gerd Kuesters
>> <rich...@humantech.com.br> wrote:
>>
>>> Yup, I agree with you, but things are a little out of hand for me to use
>>> ORM-level queries. I'll see what I can do ...
>>>
>>> Thanks! :)
>>> Cheers,
>>> Richard.
>>>
>>> On 04/25/2013 11:31 AM, Michael Bayer wrote:
>>>> you'd need to organize things differently for the column grabbing to work
>>>> out.
>>>>
>>>> I'd advise producing the query using ORM-level Query in the first place so
>>>> that you don't need to use from_statement(), which is really a last resort
>>>> system.
>>>>
>>>>
>>>> On Apr 25, 2013, at 10:27 AM, Richard Gerd Kuesters
>>>> <rich...@humantech.com.br> wrote:
>>>>
>>>>> Well, not the desired result ... Now things justs blows :-)
>>>>>
>>>>> sqlalchemy.exc.NoSuchColumnError: "Could not locate column in row for
>>>>> column 'anon_1.level'"
>>>>>
>>>>>
>>>>> Cheers,
>>>>> Richard.
>>>>>
>>>>>
>>>>> On 04/25/2013 11:03 AM, Michael Bayer wrote:
>>>>>> why not just say session.query(MyObj, q.alias()) ? creating
>>>>>> ad-hoc mappers is relatively expensive.
>>>>>>
>>>>>>
>>>>>>
>>>>>> On Apr 25, 2013, at 8:56 AM, Richard Gerd Kuesters
>>>>>> <rich...@humantech.com.br> wrote:
>>>>>>
>>>>>>> Well, probably nevermind because I made a workaround that satisfies me
>>>>>>> (may not be elegant, but that's OK).
>>>>>>>
>>>>>>> Basically, I created the "o" type a little different: "o =
>>>>>>> type('MyObjExt', (Base,), {'__table__':q.alias('q')})" and append it to
>>>>>>> the query like: "session.query(MyObj, o).from_statement(q).all()"
>>>>>>>
>>>>>>> Okay, now it returns a typle, but at least I don't have to make a
>>>>>>> second query :)
>>>>>>>
>>>>>>>
>>>>>>> Cheers,
>>>>>>> Richard.
>>>>>>>
>>>>>>> On 04/25/2013 09:41 AM, Richard Gerd Kuesters wrote:
>>>>>>>> Hi all,
>>>>>>>>
>>>>>>>> I've been playing with "sqla_hierarchy" from
>>>>>>>> https://github.com/marplatense/sqla_hierarchy .
>>>>>>>>
>>>>>>>> The problem is: the returned query appends 3 columns: level (Integer),
>>>>>>>> is_leaf (Boolean) and connect_path (pg ARRAY).
>>>>>>>>
>>>>>>>> So far, so good. If I execute the query using
>>>>>>>> "session.execute(q).fetchall()", it works like a charm. But, as we
>>>>>>>> know, "session.execute" returns a RowProxy, not objects. Using
>>>>>>>> "session.query(MyObj).from_statement(q).all()", I'm able to get my
>>>>>>>> mapped objects, but without the extra columns that would make me very
>>>>>>>> pleased (level, is_leaf, connect_path). Is there a way to get around
>>>>>>>> this?
>>>>>>>>
>>>>>>>> I have done testings using "o = type('MyObjExt', (MyObj,),
>>>>>>>> {'__table__': q}" and them use it on the session.query, *but* it
>>>>>>>> looses foreign key references - or, well, I don't know how to
>>>>>>>> "explain" this to the mapper (?), since MyObj is polymorphic (probably
>>>>>>>> the pitfall?).
>>>>>>>>
>>>>>>>>
>>>>>>>> Thanks for your time and help.
>>>>>>>>
>>>>>>>> Best regards,
>>>>>>>> Richard.
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