Python [Django]如何解决以下错误（在views.py中）？

在使用django站点运行Howtoango第九章中给出的代码时，我在views.py中遇到以下错误：

Environment:
Request Method: POST
Request URL: http://127.0.0.1:8000/rango/register/

Django Version: 1.7
Python Version: 2.7.8
Installed Applications:
('django.contrib.admin',
 'django.contrib.auth',
 'django.contrib.contenttypes',
 'django.contrib.sessions',
 'django.contrib.messages',
 'django.contrib.staticfiles',
 'rango')
Installed Middleware:
('django.contrib.sessions.middleware.SessionMiddleware',
 'django.middleware.common.CommonMiddleware',
 'django.middleware.csrf.CsrfViewMiddleware',
 'django.contrib.auth.middleware.AuthenticationMiddleware',
 'django.contrib.auth.middleware.SessionAuthenticationMiddleware',
 'django.contrib.messages.middleware.MessageMiddleware',
 'django.middleware.clickjacking.XFrameOptionsMiddleware')


Traceback:
File "C:\Users\Blue\Anaconda\lib\site-packages\django\core\handlers\base.py"        in get_response
  111.                     response = wrapped_callback(request,      *callback_args, **callback_kwargs)
File "C:\Users\Blue\code\tango_with_django_project\rango\views.py" in     register
  78.         user_form=UserForm(data=request.POST)

Exception Type: TypeError at /rango/register/
Exception Value: this constructor takes no arguments

用户表单代码：

class UserForm:
password=forms.CharField(widget=forms.PasswordInput())
class Meta:
    model=User
    fields=('username','email','password')

！！！！

---

不知道如何解决此错误请帮助

您应该从

ModelForm

继承

UserForm

：

class UserForm(forms.ModelForm):
    ...

---

请显示

用户表单的代码。