well in this example youre not really getting what you want in any
case. youre trying to depend upon the eager load conditions already
joining in the "cities" table but thats not really how that was meant
to be done; the eager/lazy load thing is meant to be as transparent
as possible from the rest of the query.
first of all, you have to turn echo=True to see what its doing; else
theres less than zero chance of understanding how this works.
So really, even the working example you have, you mean to do this:
ret = m.select(and_(cities.c.city_name == 'Rome',
users.c.city_id==cities.c.city_id), limit=10)
The non-working example, the "city" table is not getting stuck into
the query since its not in the expression at all. SA should support
a "from_obj" parameter here so that you can stick the "cities" table
in the inner expression, it doesnt seem to be really working. i can
make it work if i do this:
ret = m.select(and_("city_name = 'Rome'",
users.c.city_id==cities.c.city_id) , limit=10)
basically things get a lot more tricky when you have eager loading
turned on.
On May 4, 2006, at 6:30 AM, Sandro Dentella wrote:
Hi everybody,
in the script reported below mapper.select will fail in presence of
'limit' parameter if the condition is given as literal rather
than with
column object and the mapper is a join:
ret = m.select(cities.c.city_name == 'Rome' , limit=10)
#ret = m.select("city_name = 'Rome'" , limit=10) ### FAILS
on the other hand
ret = m.select("user_id > 2", limit=10)
will also work, since the field on which I filter is from the first
table
of the join. If I understand this depends on the way limit is
implemented.
If I understand correctly the docs, sqlalchemy will try to limit on
the
number of instances of the first table while I'd like to limit on the
resulting rowset, is there any way of achieving this?
Thanks in advance
sandro
*:-)
from sqlalchemy import *
#eng = create_engine("sqlite://filename=test-sql.db", echo=False)
eng = create_engine("sqlite://", echo=False)
cities = Table('city', eng,
Column('city_id', Integer, primary_key = True),
Column('city_name', String(30)),
Column('country', String(30), nullable = False)
)
users = Table('users', eng,
Column('user_id', Integer, primary_key = True),
Column('user_name', String(30), nullable = False),
Column('city_id', String(30), ForeignKey
("city.city_id"), nullable = False),
)
users.create()
users.insert().execute(
{'user_id': 1 , 'user_name': 'Sam', 'city_id' : '1' },
{'user_id': 2 , 'user_name': 'Sid', 'city_id' : '1' },
{'user_id': 3 , 'user_name': 'Axe', 'city_id' : '2' },
{'user_id': 4 , 'user_name': 'Ted', 'city_id' : '2' })
cities.create()
cities.insert().execute(
{'city_id': 1, 'city_name': 'Rome', 'country': 'Italy'},
{'city_id': 2, 'city_name': 'Paris', 'country': 'France'},
)
class User(object): pass
class City(object): pass
c2 = mapper(City, cities)
rel2 = relation(c2, lazy=False, )
m = mapper(User, users, properties = { 'cities' : rel2 } )
ret = m.select("user_id > 2", limit=10)
ret = m.select(cities.c.city_name == 'Rome' , limit=10)
#ret = m.select("city_name = 'Rome'" , limit=10)
ret = m.select("city_name = :city_name" , params={'city_name' :
'Rome'})
--
Sandro Dentella *:-)
e-mail: [EMAIL PROTECTED]
http://www.tksql.org TkSQL Home page - My GPL work
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