more pythonic

[Paul McGuire]

On Feb 28, 8:58 am, Temoto <temo... at gmail.com> wrote:
> On 28 ÆÅ×, 15:42, Paul McGuire <pt... at austin.rr.com> wrote:
>
>
>
>
>
> > On Feb 28, 5:40 am, Temoto <temo... at gmail.com> wrote:
>
> > > Hello.
>
> > > There is a Django application, i need to place all its data into
> > > Access mdb file and send it to user.
> > > It seems to me that params filling for statement could be expressed in
> > > a more beautiful way.
> > > Since i'm very new to Python, i don't feel that, though.
>
> > > Could you tell your opinion on that snippet?
>
> > > <code>
> > >     sql = """insert into salesmanager
> > >         (employeeid, name, officelocation, departmentname, salary)
> > >         values (?, ?, ?, ?, ?);"""
> > >     params = []
> > >     for manager in Manager.objects.all():
> > >         params.append( (manager.id, manager.name, manager.office,
> > > manager.department, manager.salary) )
> > >     curs.executemany(sql, params)
> > > </code>
>
> > Replace:
> >     params = []
> >     for manager in Manager.objects.all():
> >         params.append( (manager.id, manager.name,
> >                         manager.office, manager.department,
> >                         manager.salary) )
>
> > With this list comprehension:
>
> >     params = [ (mgr.id, mgr.name, mgr.office,
> >                  mgr.department, mgr.salary)
> >                 for mgr in Manager.objects.all() ]
>
> > But the technique you are using, of creating a params list instead of
> > doing explicit string construction, IS the safe SQL-injection-
> > resistant way to do this.
>
> > -- Paul
>
> Thanks a lot. I've been actually waiting for a list comprehension.- Hide quoted text -
>
> - Show quoted text -

In general, whenever you have:

    someNewList = []
    for smthg in someSequence:
        if condition(smthg):
            someNewList.append( elementDerivedFrom(smthg) )

replace it with:

    someNewList = [ elementDerivedFrom(smthg)
                      for smthg in someSequence
                        if condition(smthg) ]

-- Paul