Limiting available choices in a Django formset - django

Question

I have a formset which has a field "Teams" which should be limited to the teams the current user belongs to.
def edit_scrapbook(request):
u=request.user
ScrapbookAjaxForm = modelformset_factory(Scrapbook, fields=
('description','status','team'))
choices=False
for t in u.team_set.all():
if choices:
choices=choices,(t.id,t.name)
else:
choices=choices,(t.id,t.name)
if request.method == 'POST':
formset = ScrapbookAjaxForm(request.POST,
queryset=Scrapbook.objects.filter(owner=u))
if formset.is_valid():
instances=formset.save(commit=False)
for i in instances:
i.owner=request.user
i.save()
formset.save_m2m()
return HttpResponseRedirect(reverse('scrapbooks.views.index'))
else:
formset = ScrapbookAjaxForm(queryset=Scrapbook.objects.filter(owner=u))
for form in forms:
for field in form:
if field.label == 'Team':
field.choices=choices
c=RequestContext(request)
return render_to_response('scrapbooks/ajax_edit.html',
{'fs':formset},context_instance=c)
This does not seem to affect the choices in the form at all. This is quite ugly and probably the result of looking at this problem for way too long. I have also tried using a custom formset but I can't seem to get the custom formset to accept the parameter.
How do I limit the choices for the Team field on my subselect in a formset based on the teams the user is in?

Answer 1

From django model documentation:
Finally, note that choices can be any
iterable object -- not necessarily a
list or tuple. This lets you construct
choices dynamically. But if you find
yourself hacking choices to be
dynamic, you're probably better off
using a proper database table with a
ForeignKey. choices is meant for
static data that doesn't change much,
if ever.
I would use then the same idea: in the form, you use a ForeignKey for the team and then, you can limit that list with some query.
Some further suggestion:
Use a ForeignKey for the team
Define your own ModelChoiceField, with a query that will limit its content, basing on a parameter given in its initialization.
Override the default field type, to use your own ModelChoiceField. Note that you should pass the filter for the team in the initialization of your ModelChoiceField.

Answer 2

Not sure if this is the cause of the issue, but there's a big problem with the way you build up the choices tuple.
After four teams, choices will look like this:
((((False, (1, u'Team 1')), (2L, u'Team 2')), (3, u'Team 3')), (4, u'Team 4'))
which obviously isn't valid for setting a choice field. A much better way of doing it would be to use a list comprehension in place of the whole loop:
choices = [(t.id,t.name) for t in u.team_set.all()]