Perhaps you could add the seconds as a virtual lazy field.
On Wednesday, March 21, 2012 11:25:41 PM UTC-7, backseat wrote:
>
> On Mon, 19 Mar 2012 14:45:51 -0700 (PDT), niph...@gmail.com said:
>
> > for every "period", duration is calculated as:
> > duration = db.periods.end_time.seconds() -
> > db.periods.start_time.seconds()
> >
> > now, get a list of all "durations"...
> >
> > result = db(db.periods.id>0).select(db.periods.id, duration)
>
> This does not work: every 'duration' is None:
>
> >>> duration = db.t_periods.f_period_end.seconds() -
> db.t_periods.f_period_start.seconds()
> >>> result = db(db.t_periods.id>0).select(db.t_periods.id, duration)
> >>> result[0]
> <Row {'t_periods': <Row {'update_record': <function <lambda> at
> 0x923479c>, 't_periods_archive': <gluon.dal.Set object at 0x923924c>,
> 0x923479c>'id': 40, 'delete_record': <function <lambda> at 0x9234764>}>,
> 0x923479c>'_extra': <Row
> 0x923479c>{"(web2py_extract('second',t_periods.f_period_end) -
> 0x923479c>web2py_extract('second',t_periods.f_period_start))": None}>}>
> >>>
>
> All rows give the same result (None).
>
> I can see that what I need to be doing is calculating the end time in
> seconds and subtracting the start time in seconds, but I can't see how to
> do that via the DAL.
>
> Back to my original question: is the only way to do this to use
> hand-crafted SQL?
> --
> "You can have everything in life you want if you help enough other people
> get what they want" - Zig Ziglar.
>
> Who did you help today?
>
>
