Как передать значение из формы методом GET?

Ошибка: Cannot use None as a query value

views.py

class DaySheetListView(ListView):
    model = Sheet
    context_object_name = 'sheet_list'
    template_name = 'sheet/search_results.html'

    def get_queryset(self):
        query = self.request.GET.get('qe')
        if query == 'all':
            return Sheet.objects.filter()
        elif query == 'month':
            return Sheet.objects.filter()
        elif query == 'week':
            return Sheet.objects.filter()
        elif query == 'day':
            return Sheet.objects.filter()

trmplates

<form action="{% url 'day_results' %}" method="get">
    <input type="radio" name="qe" value="day" placeholder="День" aria-label="День">День
    <input type="radio" name="qe" value="week" placeholder="Неделя" aria-label="Неделя">Неделя
    <input type="radio" name="qe" value="month" placeholder="Месяц" aria-label="Месяц">Месяц
    <input type="radio" name="qe" value="all" placeholder="Все" aria-label="Все" checked>Все
    <button type="submit">Отправить</button>
</form>