ModelChoiceField gets an error when you pass an String instead of an integer

[Oriol Martí]

When you have a ModelChoiceField field and you pass an String instead of an Integer you have an error.
If a user sends a string (GET or POST) to the page an error occurs. Here is an example of this error:

from django import newforms as forms
from django.utils.translation import ugettext as _
from satchmo.l10n.models import Country

class AdvSearch (forms.Form):

... country = forms.ModelChoiceField(Country.objects.all(), required=False, label = _("Country"))
...

f = AdvSearch({"country":"gg"})
if f.is_valid():

... print "VALID"
... else:
... print "NO VALID"
...
Traceback (most recent call last):

File "<stdin>", line 1, in <module>
File "/home/sinuhe/lib/python2.5/django/newforms/forms.py", line 95, in is_valid

This error can be corrected if you check the parameters that the user is sending, but I think that the best behavior when this happens is the same if you send an Integer that not exists in the Query.