tornado 用 django 的 MultiValueDict 处理 wtforms 出错

代码：
import wtforms
from wtforms import validators
from django.utils.datastructures import MultiValueDict


class Form(wtforms.Form):
def __init__(self, handler=None, obj=None, prefix='',
formdata=None, **kwargs):
if handler:
formdata = MultiValueDict()
for name in handler.request.arguments.keys():
formdata.setlist(name, handler.get_argument(name))

#下面这个地方初始化Form的时候formdata的数据全都丢失了。比如本来是SSS的变成了S
wtforms.Form.__init__(self, formdata, obj, prefix, **kwargs)


class PostForm(Form):
title = wtforms.TextField(u'Title', validators=[validators.Required()])
content = wtforms.TextAreaField(u'Content',
validators=[validators.Required()])

python菜鸟，求前辈解答，感激不尽。google没找到答案。