Django:关键字参数"initial"的多个值 [英] Django: multiple values for keyword argument 'initial'

问题描述

在Django上，我得到了此追溯:

On Django I'm getting this traceback:

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'

对于基于此代码的代码，请创建一个Django表单以保存两个模型:

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 __()的签名未更改.而且，更奇怪的是，Django更详细的回溯显示，对于回溯中的每个步骤， argv 总是 ， {} ，所以我我什至不知道错误来自哪一点追溯.

As you can see, the signature of __init__() is not changed. Also, more strangely, Django's more detailed traceback shows that for each step in the traceback, the argv is always, {}, so I'm not even sure at what point of the traceback the error comes from.

推荐答案

对于ModelForm， __ init __ 函数签名不正确.

The __init__ function signature is incorrect for a ModelForm.

来自 BaseModelForm的Django来源您可以看到函数签名是:

From the Django source for BaseModelForm you can see that the function signature is:

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那样在第一个位置使用未命名的参数实例化您的表单，那么您将最终遇到此错误.

So if anyone instantiates your form with an unnamed argument in the first position as Django does, then you'll end up with this error.

我建议像这样重写您的 __ init __ :

I'd suggest rewriting your __init__ like this:

 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))

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