On Fri, 2007-08-17 at 08:22 +0000, james_027 wrote:
> hi,
>
> while learning and experimenting with forms ... one should use
> ModelChoiceField in order to let newforms bind the value on a
> foreignkey field of a model. My concern is that in the real world, you
> usually don't use <select></select> to let the user chose the value
> to be filled especially if the list of choices is very very large.
> While I have success with ModelChoiceField(Item.object.all(),
> widget=TextInput), providing a <input type="text"></input> for
> entering a value which could come from a selected record thru
> searching, my concerned/question is ...
[...]
> (I hope during the assignment ii.item = f.item, the Item.objects.all()
> is not executed but instead it will do something like
> item.objects.all().filter(id="value from the text input"). If this is
> the case then I have no problem with this approach but if not could
> some share their solution?)
This is one of those questions where looking at the source for
ModelChoiceField would be the easiest way to answer it. It's only Python
code and not particularly difficult stuff at that (once you have worked
with QuerySets a bit). It really is the best way to learn and it's one
of the reasons the code is commented.
In this case, the queryset is used to generate the choices list. When
cleaning and normalizing, you can see that the clean() method does
value = self.queryset.model._default_manager.get(pk=value)
There was a thread recently on django-dev about whether using
_default_manager or the queryset is the right thing to do here. No firm
conclusions yet, because there are genuine arguments both ways. So just
realise is uses the default manager.
Regards,
Malcolm
--
Depression is merely anger without enthusiasm.
http://www.pointy-stick.com/blog/
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