Jim, I thought that at first too. :)
2014-04-28 16:06 GMT-03:00 Niphlod <niph...@gmail.com>: > seems to me that you should use windowing functions instead.... > > there's no need to introduce a new method.... you can use expression > themselves in the select, and extract the field as usual > > myexpr = 'first_value(b_field) over (partition by a_field order by > b_field)' > rows = db2(db2.test_table.id > 0).select(myexpr, db2.test_table.a_field) > for row in rows: > print row.aa, row[myexpr] > > > > > On Monday, April 28, 2014 4:46:43 PM UTC+2, Manuele wrote: >> >> Il 28/04/14 16:05, Carlos Costa ha scritto: >> > I think he is looking for the first record of each group, not the >> > first record of the entire result. >> > I think there is no such function in web2py yet. >> > >> > I have performed a similar task for reporting using this: >> > https://docs.python.org/2/library/itertools.html#itertools.groupby >> > >> > It will require more computation and memory as you will have do it in >> > memory but is possible and simple. >> starting from the point I'm using postgresql (v. 9.3) I was thinking >> about introducing a new method to the class Expression in dal defined as >> follows: >> >> def array_agg(self): >> db = self.db >> return Expression(db, db._adapter.AGGREGATE, self, 'array_agg', >> self.type) >> >> and get the first argument of the returned list. >> >> maybe this method can be introduced in the dal code but for the moment >> Is there a way to locally "monkey patch" the Expression class for my >> application? >> >> thank you >> Cheers >> >> Manuele >> > -- > Resources: > - http://web2py.com > - http://web2py.com/book (Documentation) > - http://github.com/web2py/web2py (Source code) > - https://code.google.com/p/web2py/issues/list (Report Issues) > --- > You received this message because you are subscribed to the Google Groups > "web2py-users" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to web2py+unsubscr...@googlegroups.com. > For more options, visit https://groups.google.com/d/optout. > -- Att. Carlos J. Costa Cientista da Computação Esp. Gestão em Telecom EL MELECH NEEMAN! אָמֵן -- Resources: - http://web2py.com - http://web2py.com/book (Documentation) - http://github.com/web2py/web2py (Source code) - https://code.google.com/p/web2py/issues/list (Report Issues) --- You received this message because you are subscribed to the Google Groups "web2py-users" group. To unsubscribe from this group and stop receiving emails from it, send an email to web2py+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
