I see the fine distinction is that python has decimal 'support' but no
decimal 'type'
The decimal 'support' is described here
http://www.network-theory.co.uk/docs/pytut/DecimalFloatingPointArithmetic.html
I don't see how you can mimic aggregation of a decimal type using that
'virtual' decimal idea within a SQL query
unless you introduce some private SQL Functions to mimic 'virtual
decimal based on int' on the SQL Engine side.
And mimic logic can become a performance issue.
It still looks like complete native SQL decimal type support through
and through web2py would be great.
On May 24, 12:42 am, mdipierro <mdipie...@cs.depaul.edu> wrote:
> Mission control is convinced there is no real reason not to use double
> since, even if the database may store them as decimals there is no
> decimal type in python, hence this extra conversion can only hurt
> you.
>
> You can very much mimic decimals using validators:
>
> class IS_DECIMAL:
> def __init__
> (self,decimals=2,minimum=-10**9,maximum=10**9,error_message='bla bla
> bla'):
> self.decimals=decimals
> self.minimum=minimum
> self.maximum=maximum
> self.error_message=error_message
> def __call__(self,value):
> (v,e)=IS_FLOAT_IN_RANGE
> (self.minimum,self.maximum,self.error_message)(value)
> if e:
> return (v,e)
> return int(v*(10**self.decimals))
> def formatter(self,value):
> return float(value)/(10**self.decimals)
>
> SQLField('myfield','integer',requires=IS_DECIMAL())
>
> In this way you store is as a long integer and always process it as an
> integer but you display is with a decimal point.
>
> On May 23, 7:08 pm, dlypka <dly...@gmail.com> wrote:
>
>
>
> > A workaround (until web2py mission control can be convinced to support
> > decimal type) would be to store them as string (similar to BCD
> > concept)
> > and then convert to python decimal when needed. Luckily python itself
> > supports decimal.
>
> > On May 23, 7:56 pm, Pystar <aitoehi...@gmail.com> wrote:
>
> > > Cant you use "float" when specifying the field type in the database
> > > definition?
>
> > > On May 23, 9:43 pm, "Francois (Jersey)"
>
> > > <francois.ches...@googlemail.com> wrote:
> > > > Dear all,
>
> > > > Having a numeric/decimal support for web2py is key to produce
> > > > applications including accounting or financial aspects, and there had
> > > > been discussions about it back in March.
>
> > > > I understand that the reason for not including decimal or numerical is
> > > > that it is not supported by all the database.
>
> > > > Mysql, postgre and sqlite all support this numeric/decimal feature.
>
> > > > I would be keen to contribute an accounting software to web2py, but I
> > > > need DECIMAL or NUMERIC support.
>
> > > > Any comments for or against.
>
> > > > Francois
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