python - Django:关键字参数 'initial' 的多个值

Question

在 Django 上我得到了这个回溯:

File "/Users/eeytan/ddragon/lib/python2.7/site-packages/django/core/handlers/base.py" in get_response
  115.                         response = callback(request, *callback_args, **callback_kwargs)
File "/Users/eeytan/ddragon/lib/python2.7/site-packages/django/contrib/admin/options.py" in wrapper
  372.                 return self.admin_site.admin_view(view)(*args, **kwargs)
File "/Users/eeytan/ddragon/lib/python2.7/site-packages/django/utils/decorators.py" in _wrapped_view
  91.                     response = view_func(request, *args, **kwargs)
File "/Users/eeytan/ddragon/lib/python2.7/site-packages/django/views/decorators/cache.py" in _wrapped_view_func
  89.         response = view_func(request, *args, **kwargs)
File "/Users/eeytan/ddragon/lib/python2.7/site-packages/django/contrib/admin/sites.py" in inner
  202.             return view(request, *args, **kwargs)
File "/Users/eeytan/ddragon/lib/python2.7/site-packages/django/utils/decorators.py" in _wrapper
  25.             return bound_func(*args, **kwargs)
File "/Users/eeytan/ddragon/lib/python2.7/site-packages/django/utils/decorators.py" in _wrapped_view
  91.                     response = view_func(request, *args, **kwargs)
File "/Users/eeytan/ddragon/lib/python2.7/site-packages/django/utils/decorators.py" in bound_func
  21.                 return func(self, *args2, **kwargs2)
File "/Users/eeytan/ddragon/lib/python2.7/site-packages/django/db/transaction.py" in inner
  223.                 return func(*args, **kwargs)
File "/Users/eeytan/ddragon/lib/python2.7/site-packages/django/contrib/admin/options.py" in change_view
  1085.             form = ModelForm(request.POST, request.FILES, instance=obj)

Exception Type: TypeError at /admin/dragon_portal/parentprofile/1/
Exception Value: __init__() got multiple values for keyword argument 'instance'

此代码基于 Creating one Django Form to save two models :

class ParentCreationForm(UserCreationForm):
    first_name  = forms.CharField(max_length=100)
    last_name   = forms.CharField(max_length=100)
    email       = forms.EmailField()
    #ice_contact = forms.CharField(max_length=100)
    #notes       = HTMLField()

    def __init__(self, instance=None, *args, **kwargs):
        _fields = ('username', 'first_name', 'last_name', 'email', 'password')
        _initial = model_to_dict(instance.dragonuser, _fields) \
            if instance is not None else {}
        kwargs['initial'] = _initial
        super(ParentCreationForm, self).__init__(instance=instance, *args, **kwargs)
        self.fields.update(fields_for_model(DragonUser, _fields))

如您所见，__init__() 的签名没有更改。另外，更奇怪的是，Django 更详细的回溯显示，对于回溯中的每一步，argv 都是always，{}，所以我'我什至不确定错误来自回溯的哪个点。

Answer 1

__init__ 函数签名对于 ModelForm 来说不正确。

来自Django source for BaseModelForm你可以看到函数签名是:

def __init__(self, data=None, files=None, auto_id='id_%s', prefix=None,
                 initial=None, error_class=ErrorList, label_suffix=None,
                 empty_permitted=False, instance=None):

因此，如果有人像 Django 一样在第一个位置使用未命名参数实例化您的表单，那么您最终会遇到此错误。

我建议像这样重写你的__init__:

 def __init__(self, *args, **kwargs):
        instance = kwargs.get('instance')
        _fields = ('username', 'first_name', 'last_name', 'email', 'password')
        _initial = model_to_dict(instance.dragonuser, _fields) \
            if instance is not None else {}
        kwargs['initial'] = _initial
        super(ParentCreationForm, self).__init__(*args, **kwargs)
        self.fields.update(fields_for_model(DragonUser, _fields))