如何在提交后将Django表单域设置为空？

from django.shortcuts import render
from .forms import MyForm

def my_view(request):
    if request.method == 'POST':
        form = MyForm(request.POST)
        if form.is_valid():
            # 获取表单数据
            cleaned_data = form.cleaned_data

            # 将表单域设置为空
            cleaned_data['field_name'] = None

            # 保存表单数据或执行其他操作

            return render(request, 'success.html')
    else:
        form = MyForm()

    return render(request, 'my_form.html', {'form': form})