Fantastic: and now i don't need the join to the persons table anymore
- it stays hidden inside the message object, so i can just ask for
"sender.name" or whatever i want - that's nice - If I have the
objects, i can delegate the use of them to others, maybe leading to
higher level of reuse (= less bugs) of the 'sql'.
Me on sqlalchemy:
"""
One of the things, I like about sql, is it's language
independency -
it can be discussed with almost all programmers and
powerusers and even to some extent with laymen.
With this set of tools I can (i hope;-) accomodate two things -
take some of the tedious things away from expressing
myself in sql but still have sql (kindly provided by sqlalchemy),
that i can discuss with powerusers"""
k = model.message_table.alias('k')
m = model.message_table
return dbsession.query(model.Message).\
filter(m.c.toid==79487281).\
filter(~exists([1], and_(
k.c.toid==m.c.fromid,
k.c.fromid==m.c.toid,
k.c.sent>m.c.sent))
).\
order_by(desc(m.c.sent)).list()
On Jun 19, 12:03 am, gardsted <[EMAIL PROTECTED]> wrote:
> Thank You very much
> Worked like a charm - only better - now I get objects.
> I will now see, if I can understand what goes on ;-)
> The results were the same rows.
>
> def play5():
> print ############### play5 #################
> k = model.message_table.alias('k')
> s = model.person_table
> m = model.message_table
> result=dbsession.query(model.Message).select_from(
> m.join(s,m.c.fromid==s.c.personid)).\
> filter(m.c.toid==123456).\
> filter(~exists([1], and_(
> k.c.toid==m.c.fromid,
> k.c.fromid==m.c.toid,
> k.c.sent>m.c.sent))
> ).\
> order_by(desc(m.c.sent)).list()
> for i in result:
> print i
>
> On Jun 18, 11:27 pm, Michael Bayer <[EMAIL PROTECTED]> wrote:
>
> > On Jun 18, 2007, at 4:52 PM, gardsted wrote:
>
> > > Dear List.
> > > How do I do this more ormish?
>
> > > The statement is supposed to find the latest messages which havent yet
> > > been answered
> > > by 123456, assuming a later message is an answer;-)
>
> > > def play4():
> > > print ############### play4 #################
> > > engine=create_engine(dburi)
> > > result=engine.execute("""
> > > select m.fromid, s.name, m.sent from person s,message m
> > > where toid=123456 and
> > > s.personid = m.fromid and not exists (
> > > select 1 from message k where
> > > k.toid=m.fromid and k.fromid=m.toid
> > > and k.sent > m.sent
> > > )
> > > order by m.sent desc
> > > """)
> > > ...
>
> > > I completely fail to grasp how I get from the straight sql-
> > > representation to the part where i
> > > can actually benefit from the orm
>
> > > Here am I: I have created a mapper where each message knows it's
> > > sender and receiver by foreign key and attribute like this (and this I
> > > like very much):
> > > message_mapper=mapper(
> > > Message,
> > > message_table,
> > > properties={
> > > "sender": relation(Person,
> > > primaryjoin=(message_table.c.fromid==Person.c.personid)),
> > > "receiver": relation(Person,
> > > primaryjoin=(message_table.c.toid==Person.c.personid))
> > > }
> > > )
>
> > here are some rough approaches.
>
> > text:
>
> > session.query(Message).select_text("""select m.* from person s,
> > message m
> > where toid=123456 and
> > s.personid = m.fromid and not exists (
> > select 1 from message k where
> > k.toid=m.fromid and k.fromid=m.toid
> > and k.sent > m.sent
> > )
> > order by m.sent desc""")
>
> > hybrid:
>
> > session.query(Message).select_from(messages.join(person)).filter
> > ("""toid=123456 and not exists (
> > select 1 from message k where
> > k.toid=messages.fromid and k.fromid=messages.toid
> > and k.sent > messages.sent
> > )""").order_by(desc(Message.c.sent)).list()
>
> > fully constructed:
>
> > k = messages.alias('k')
> > session.query(Message).select_from(messages.join(person)).filter
> > (messages.c.toid==123456).\
> > filter(~exists([1], and_(k.c.toid==messages.c.fromid,
> > k.c.fromid==messages.c.toid, k.c.send>messages.c.sent))).\
> > order_by(desc(messages.c.sent)).list()
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