限制Django表单集中的可用选项

我有一个表单集,其中有一个字段“团队”,该字段应仅限于当前用户所属的团队。

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)

这似乎根本不会影响表格中的选择。这相当丑陋,可能是长时间关注这个问题的结果。我也尝试过使用自定义表单集,但似乎无法让自定义表单集接受该参数。