问题:Django将自定义表单参数传递给Formset

这在Django 1.9中用form_kwargs修复

我有一个看起来像这样的Django表单:

class ServiceForm(forms.Form):
    option = forms.ModelChoiceField(queryset=ServiceOption.objects.none())
    rate = forms.DecimalField(widget=custom_widgets.SmallField())
    units = forms.IntegerField(min_value=1, widget=custom_widgets.SmallField())

    def __init__(self, *args, **kwargs):
        affiliate = kwargs.pop('affiliate')
        super(ServiceForm, self).__init__(*args, **kwargs)
        self.fields["option"].queryset = ServiceOption.objects.filter(affiliate=affiliate)

我称这种形式是这样的:

form = ServiceForm(affiliate=request.affiliate)

request.affiliate登录用户在哪里。这按预期工作。

我的问题是我现在想将此单一表单转换为表单集。我不知道的是在创建表单集时如何将会员信息传递给各个表单。根据文档来制作一个表单集,我需要做这样的事情:

ServiceFormSet = forms.formsets.formset_factory(ServiceForm, extra=3)

然后我需要这样创建它:

formset = ServiceFormSet()

现在如何以这种方式将affiliate = request.affiliate传递给各个表单?

This was fixed in Django 1.9 with form_kwargs.

I have a Django Form that looks like this:

class ServiceForm(forms.Form):
    option = forms.ModelChoiceField(queryset=ServiceOption.objects.none())
    rate = forms.DecimalField(widget=custom_widgets.SmallField())
    units = forms.IntegerField(min_value=1, widget=custom_widgets.SmallField())

    def __init__(self, *args, **kwargs):
        affiliate = kwargs.pop('affiliate')
        super(ServiceForm, self).__init__(*args, **kwargs)
        self.fields["option"].queryset = ServiceOption.objects.filter(affiliate=affiliate)

I call this form with something like this:

form = ServiceForm(affiliate=request.affiliate)

Where request.affiliate is the logged in user. This works as intended.

My problem is that I now want to turn this single form into a formset. What I can’t figure out is how I can pass the affiliate information to the individual forms when creating the formset. According to the docs to make a formset out of this I need to do something like this:

ServiceFormSet = forms.formsets.formset_factory(ServiceForm, extra=3)

And then I need to create it like this:

formset = ServiceFormSet()

Now how can I pass affiliate=request.affiliate to the individual forms this way?


回答 0

我会用functools.partialfunctools.wraps

from functools import partial, wraps
from django.forms.formsets import formset_factory

ServiceFormSet = formset_factory(wraps(ServiceForm)(partial(ServiceForm, affiliate=request.affiliate)), extra=3)

我认为这是最干净的方法,并且不会以任何方式影响ServiceForm(即,使子类难以继承)。

I would use functools.partial and functools.wraps:

from functools import partial, wraps
from django.forms.formsets import formset_factory

ServiceFormSet = formset_factory(wraps(ServiceForm)(partial(ServiceForm, affiliate=request.affiliate)), extra=3)

I think this is the cleanest approach, and doesn’t affect ServiceForm in any way (i.e. by making it difficult to subclass).


回答 1

正式文件方式

Django 2.0:

ArticleFormSet = formset_factory(MyArticleForm)
formset = ArticleFormSet(form_kwargs={'user': request.user})

https://docs.djangoproject.com/zh-CN/2.0/topics/forms/formsets/#passing-custom-parameters-to-formset-forms

Official Document Way

Django 2.0:

ArticleFormSet = formset_factory(MyArticleForm)
formset = ArticleFormSet(form_kwargs={'user': request.user})

https://docs.djangoproject.com/en/2.0/topics/forms/formsets/#passing-custom-parameters-to-formset-forms


回答 2

我将在一个函数中动态构建表单类,以便它可以通过闭包访问关联:

def make_service_form(affiliate):
    class ServiceForm(forms.Form):
        option = forms.ModelChoiceField(
                queryset=ServiceOption.objects.filter(affiliate=affiliate))
        rate = forms.DecimalField(widget=custom_widgets.SmallField())
        units = forms.IntegerField(min_value=1, 
                widget=custom_widgets.SmallField())
    return ServiceForm

另外,您不必在选项字段中重写查询集。缺点是子类化有点时髦。(任何子类都必须以类似的方式创建。)

编辑:

为了回应评论,您可以在使用类名的任何地方调用此函数:

def view(request):
    affiliate = get_object_or_404(id=request.GET.get('id'))
    formset_cls = formset_factory(make_service_form(affiliate))
    formset = formset_cls(request.POST)
    ...

I would build the form class dynamically in a function, so that it has access to the affiliate via closure:

def make_service_form(affiliate):
    class ServiceForm(forms.Form):
        option = forms.ModelChoiceField(
                queryset=ServiceOption.objects.filter(affiliate=affiliate))
        rate = forms.DecimalField(widget=custom_widgets.SmallField())
        units = forms.IntegerField(min_value=1, 
                widget=custom_widgets.SmallField())
    return ServiceForm

As a bonus, you don’t have to rewrite the queryset in the option field. The downside is that subclassing is a little funky. (Any subclass has to be made in a similar way.)

edit:

In response to a comment, you can call this function about any place you would use the class name:

def view(request):
    affiliate = get_object_or_404(id=request.GET.get('id'))
    formset_cls = formset_factory(make_service_form(affiliate))
    formset = formset_cls(request.POST)
    ...

回答 3

这是对我有效的Django 1.7:

from django.utils.functional import curry    

lols = {'lols':'lols'}
formset = modelformset_factory(MyModel, form=myForm, extra=0)
formset.form = staticmethod(curry(MyForm, lols=lols))
return formset

#form.py
class MyForm(forms.ModelForm):

    def __init__(self, lols, *args, **kwargs):

希望它能对某人有所帮助,花了我足够长的时间才能弄清楚;)

This is what worked for me, Django 1.7:

from django.utils.functional import curry    

lols = {'lols':'lols'}
formset = modelformset_factory(MyModel, form=myForm, extra=0)
formset.form = staticmethod(curry(MyForm, lols=lols))
return formset

#form.py
class MyForm(forms.ModelForm):

    def __init__(self, lols, *args, **kwargs):

Hope it helps someone, took me long enough to figure it out ;)


回答 4

我喜欢闭包解决方案,因为它更“干净”,并且使用了更多的Python语言(因此对+1表示响应),但Django表单也具有可用于过滤表单集中的查询集的回调机制。

它也没有记录,我认为这表明Django开发人员可能不太喜欢它。

因此,您基本上创建了相同的表单集,但添加了回调:

ServiceFormSet = forms.formsets.formset_factory(
    ServiceForm, extra=3, formfield_callback=Callback('option', affiliate).cb)

这将创建一个如下所示的类的实例:

class Callback(object):
    def __init__(self, field_name, aff):
        self._field_name = field_name
        self._aff = aff
    def cb(self, field, **kwargs):
        nf = field.formfield(**kwargs)
        if field.name == self._field_name:  # this is 'options' field
            nf.queryset = ServiceOption.objects.filter(affiliate=self._aff)
        return nf

这应该给您大致的想法。使回调成为这样的对象方法要稍微复杂一些,但是与执行简单的函数回调相比,它具有更多的灵活性。

I like the closure solution for being “cleaner” and more Pythonic (so +1 to mmarshall answer) but Django forms also have a callback mechanism you can use for filtering querysets in formsets.

It’s also not documented, which I think is an indicator the Django devs might not like it as much.

So you basically create your formset the same but add the callback:

ServiceFormSet = forms.formsets.formset_factory(
    ServiceForm, extra=3, formfield_callback=Callback('option', affiliate).cb)

This is creating an instance of a class that looks like this:

class Callback(object):
    def __init__(self, field_name, aff):
        self._field_name = field_name
        self._aff = aff
    def cb(self, field, **kwargs):
        nf = field.formfield(**kwargs)
        if field.name == self._field_name:  # this is 'options' field
            nf.queryset = ServiceOption.objects.filter(affiliate=self._aff)
        return nf

This should give you the general idea. It’s a little more complex making the callback an object method like this, but gives you a little more flexibility as opposed to doing a simple function callback.


回答 5

我想将其作为对卡尔·迈耶斯答案的评论,但由于这需要要点,因此我将其放在此处。我花了2个小时才弄清楚,所以希望对您有所帮助。

有关使用inlineformset_factory的注释。

我自己使用了该解决方案,并且效果很好,直到我使用inlineformset_factory对其进行了尝试。我正在运行Django 1.0.2,并遇到了一些奇怪的KeyError异常。我升级到最新的后备箱,并且可以直接使用。

我现在可以像这样使用它:

BookFormSet = inlineformset_factory(Author, Book, form=BookForm)
BookFormSet.form = staticmethod(curry(BookForm, user=request.user))

I wanted to place this as a comment to Carl Meyers answer, but since that requires points I just placed it here. This took me 2 hours to figure out so I hope it will help someone.

A note about using the inlineformset_factory.

I used that solution my self and it worked perfect, until I tried it with the inlineformset_factory. I was running Django 1.0.2 and got some strange KeyError exception. I upgraded to latest trunk and it worked direct.

I can now use it similar to this:

BookFormSet = inlineformset_factory(Author, Book, form=BookForm)
BookFormSet.form = staticmethod(curry(BookForm, user=request.user))

回答 6

从2012年8月14日星期二23:44:46 +0200提交e091c18f50266097f648efc7cac2503968e9d217开始,已接受的解决方案不再起作用。

当前版本的django.forms.models.modelform_factory()函数使用“类型构造技术”,在传递的表单上调用type()函数以获取元类类型,然后使用结果来构造其类对象即时输入::

# Instatiate type(form) in order to use the same metaclass as form.
return type(form)(class_name, (form,), form_class_attrs)

这意味着即使是一个curryed或partial对象,而不是一种形式的传递,也可以说是“导致鸭子咬你”:它会使用ModelFormClass对象的构造参数调用函数,并返回错误消息:

function() argument 1 must be code, not str

为了解决这个问题,我编写了一个生成器函数,该函数使用闭包返回指定为第一个参数的任何类的子类,然后在使用生成器函数的调用中提供的kwargs进行调用super.__init__之后update调用:

def class_gen_with_kwarg(cls, **additionalkwargs):
  """class generator for subclasses with additional 'stored' parameters (in a closure)
     This is required to use a formset_factory with a form that need additional 
     initialization parameters (see http://stackoverflow.com/questions/622982/django-passing-custom-form-parameters-to-formset)
  """
  class ClassWithKwargs(cls):
      def __init__(self, *args, **kwargs):
          kwargs.update(additionalkwargs)
          super(ClassWithKwargs, self).__init__(*args, **kwargs)
  return ClassWithKwargs

然后在您的代码中将表单工厂称为::

MyFormSet = inlineformset_factory(ParentModel, Model,form = class_gen_with_kwarg(MyForm, user=self.request.user))

注意事项:

  • 至少到目前为止,这很少接受测试
  • 提供的参数可能会冲突并覆盖那些将使用构造函数返回的对象的代码所使用的参数

As of commit e091c18f50266097f648efc7cac2503968e9d217 on Tue Aug 14 23:44:46 2012 +0200 the accepted solution can’t work anymore.

The current version of django.forms.models.modelform_factory() function uses a “type construction technique”, calling the type() function on the passed form to get the metaclass type, then using the result to construct a class-object of its type on the fly::

# Instatiate type(form) in order to use the same metaclass as form.
return type(form)(class_name, (form,), form_class_attrs)

This means even a curryed or partial object passed instead of a form “causes the duck to bite you” so to speak: it’ll call a function with the construction parameters of a ModelFormClass object, returning the error message::

function() argument 1 must be code, not str

To work around this I wrote a generator function that uses a closure to return a subclass of any class specified as first parameter, that then calls super.__init__ after updateing the kwargs with the ones supplied on the generator function’s call::

def class_gen_with_kwarg(cls, **additionalkwargs):
  """class generator for subclasses with additional 'stored' parameters (in a closure)
     This is required to use a formset_factory with a form that need additional 
     initialization parameters (see http://stackoverflow.com/questions/622982/django-passing-custom-form-parameters-to-formset)
  """
  class ClassWithKwargs(cls):
      def __init__(self, *args, **kwargs):
          kwargs.update(additionalkwargs)
          super(ClassWithKwargs, self).__init__(*args, **kwargs)
  return ClassWithKwargs

Then in your code you’ll call the form factory as::

MyFormSet = inlineformset_factory(ParentModel, Model,form = class_gen_with_kwarg(MyForm, user=self.request.user))

caveats:

  • this received very little testing, at least for now
  • supplied parameters could clash and overwrite those used by whatever code will use the object returned by the constructor

回答 7

卡尔·迈耶的解决方案看起来非常优雅。我尝试为modelformsets实现它。我的印象是我无法在类中调用静态方法,但是以下操作莫名其妙地起作用:

class MyModel(models.Model):
  myField = models.CharField(max_length=10)

class MyForm(ModelForm):
  _request = None
  class Meta:
    model = MyModel

    def __init__(self,*args,**kwargs):      
      self._request = kwargs.pop('request', None)
      super(MyForm,self).__init__(*args,**kwargs)

class MyFormsetBase(BaseModelFormSet):
  _request = None

def __init__(self,*args,**kwargs):
  self._request = kwargs.pop('request', None)
  subFormClass = self.form
  self.form = curry(subFormClass,request=self._request)
  super(MyFormsetBase,self).__init__(*args,**kwargs)

MyFormset =  modelformset_factory(MyModel,formset=MyFormsetBase,extra=1,max_num=10,can_delete=True)
MyFormset.form = staticmethod(curry(MyForm,request=MyFormsetBase._request))

在我看来,如果我做这样的事情:

formset = MyFormset(request.POST,queryset=MyModel.objects.all(),request=request)

然后,“ request”关键字传播到我的表单集中的所有成员表单。我很高兴,但我不知道为什么这样做有效-似乎错了。有什么建议?

Carl Meyer’s solution looks very elegant. I tried implementing it for modelformsets. I was under the impression that I could not call staticmethods within a class, but the following inexplicably works:

class MyModel(models.Model):
  myField = models.CharField(max_length=10)

class MyForm(ModelForm):
  _request = None
  class Meta:
    model = MyModel

    def __init__(self,*args,**kwargs):      
      self._request = kwargs.pop('request', None)
      super(MyForm,self).__init__(*args,**kwargs)

class MyFormsetBase(BaseModelFormSet):
  _request = None

def __init__(self,*args,**kwargs):
  self._request = kwargs.pop('request', None)
  subFormClass = self.form
  self.form = curry(subFormClass,request=self._request)
  super(MyFormsetBase,self).__init__(*args,**kwargs)

MyFormset =  modelformset_factory(MyModel,formset=MyFormsetBase,extra=1,max_num=10,can_delete=True)
MyFormset.form = staticmethod(curry(MyForm,request=MyFormsetBase._request))

In my view, if I do something like this:

formset = MyFormset(request.POST,queryset=MyModel.objects.all(),request=request)

Then the “request” keyword gets propagated to all of the member forms of my formset. I’m pleased, but I have no idea why this is working – it seems wrong. Any suggestions?


回答 8

在看到这篇文章之前,我花了一些时间试图解决这个问题。

我想到的解决方案是闭包解决方案(这是我之前在Django模型表单中使用的解决方案)。

我如上所述尝试了curry()方法,但是我无法使它与Django 1.0一起使用,因此最终我恢复为闭包方法。

闭合方法非常简洁,唯一的奇怪之处是类定义嵌套在视图或其他函数中。我认为这对我来说似乎很奇怪,这是我以前的编程经验的遗忘,而且我认为具有动态语言背景的人也不会蒙上双眼!

I spent some time trying to figure out this problem before I saw this posting.

The solution I came up with was the closure solution (and it is a solution I’ve used before with Django model forms).

I tried the curry() method as described above, but I just couldn’t get it to work with Django 1.0 so in the end I reverted to the closure method.

The closure method is very neat and the only slight oddness is that the class definition is nested inside the view or another function. I think the fact that this looks odd to me is a hangup from my previous programming experience and I think someone with a background in more dynamic languages wouldn’t bat an eyelid!


回答 9

我不得不做类似的事情。这类似于curry解决方案:

def form_with_my_variable(myvar):
   class MyForm(ServiceForm):
     def __init__(self, myvar=myvar, *args, **kwargs):
       super(SeriveForm, self).__init__(myvar=myvar, *args, **kwargs)
   return MyForm

factory = inlineformset_factory(..., form=form_with_my_variable(myvar), ... )

I had to do a similar thing. This is similar to the curry solution:

def form_with_my_variable(myvar):
   class MyForm(ServiceForm):
     def __init__(self, myvar=myvar, *args, **kwargs):
       super(SeriveForm, self).__init__(myvar=myvar, *args, **kwargs)
   return MyForm

factory = inlineformset_factory(..., form=form_with_my_variable(myvar), ... )

回答 10

基于此答案,我找到了更清晰的解决方案:

class ServiceForm(forms.Form):
    option = forms.ModelChoiceField(
            queryset=ServiceOption.objects.filter(affiliate=self.affiliate))
    rate = forms.DecimalField(widget=custom_widgets.SmallField())
    units = forms.IntegerField(min_value=1, 
            widget=custom_widgets.SmallField())

    @staticmethod
    def make_service_form(affiliate):
        self.affiliate = affiliate
        return ServiceForm

并像这样运行它

formset_factory(form=ServiceForm.make_service_form(affiliate))

based on this answer I found more clear solution:

class ServiceForm(forms.Form):
    option = forms.ModelChoiceField(
            queryset=ServiceOption.objects.filter(affiliate=self.affiliate))
    rate = forms.DecimalField(widget=custom_widgets.SmallField())
    units = forms.IntegerField(min_value=1, 
            widget=custom_widgets.SmallField())

    @staticmethod
    def make_service_form(affiliate):
        self.affiliate = affiliate
        return ServiceForm

And run it in view like

formset_factory(form=ServiceForm.make_service_form(affiliate))

回答 11

我是这里的新手,因此无法添加评论。我希望这段代码也能工作:

ServiceFormSet = formset_factory(ServiceForm, extra=3)

ServiceFormSet.formset = staticmethod(curry(ServiceForm, affiliate=request.affiliate))

至于向BaseFormSet表单集(而不是表单)添加其他参数。

I’m a newbie here so I can’t add comment. I hope this code will work too:

ServiceFormSet = formset_factory(ServiceForm, extra=3)

ServiceFormSet.formset = staticmethod(curry(ServiceForm, affiliate=request.affiliate))

as for adding additional parameters to the formset’s BaseFormSet instead of form.


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