Django: inlineformset_factory, passing parameters/variables

Question

I am fairly new with django and I am having a problem and would like to request some assistance.

I am getting an error with passing my custom param to my form that says

KeyError at /someurl
'my_arg'

    Request Method: GET
    Request URL:    http://localhost:8000/
    Django Version: 1.8.2
    Exception Type: KeyError
    Exception Value: 'my_arg'
    Exception Location: ..../forms.py in __init__, line 108(points at 'my_arg = kwargs.pop('my_arg')' line)
    Python Executable:  C:\Python27\python.exe
    Python Version: 2.7.10
    Python Path:    
    ['C:\\Users\\lolwat\\Desktop\\ITSWEBSITE',
     'C:\\Windows\\system32\\python27.zip',
     'C:\\Python27\\DLLs',
     'C:\\Python27\\lib',
     'C:\\Python27\\lib\\plat-win',
     'C:\\Python27\\lib\\lib-tk',
     'C:\\Python27',
     'C:\\Python27\\lib\\site-packages']

It also say this at the error page:

Error during template rendering
    ...
    {% for field in form %}
    ...

This is my form:

class BaseFormSet(BaseInlineFormSet):
    def __init__(self, *args, **kwargs):
    self.my_arg = kwargs.pop("my_arg")
    super(BaseFormSet, self).__init__(*args, **kwargs)

class SomeForm(ModelForm):
    ...
    def __init__(self, *args, **kwargs):
        my_arg = kwargs.pop('my_arg')
        super(SomeForm, self).__init__(*args, **kwargs)

And my views:

myformset = inlineformset_factory(modelA, modelB, formset = BaseFormSet, form=SomeForm, extra=1, can_delete=True)

def someview(request, obj_id):
    var1 = get_object_or_404(SomeModel, id = obj_id)
    somevalue = var1.ModelFieldValue
    form = myformset (request.POST, my_arg=somevalue)
    if request.method == 'POST':
        ...
    else:
        form = myformset(instance = myinstance, my_arg=somevalue)

     return render(....)

What I am doing wrong or am I doing it right? Many thanks.

UPDATE

I tried using myformset.form = staticmethod(curry(SomeForm, my_arg=somevalue))

And my views look like this:

from django.utils.functional import curry

myformset = inlineformset_factory(modelA, modelB, formset = BaseFormSet, form=SomeForm, extra=1, can_delete=True)

def someview(request, obj_id):
    var1 = get_object_or_404(SomeModel, id = obj_id)
    somevalue = var1.ModelFieldValue
    myformset.form = staticmethod(curry(SomeForm, my_arg=somevalue))
    form = myformset (request.POST, my_arg=somevalue)
    if request.method == 'POST':
        ...
    else:
        form = myformset(instance = myinstance, my_arg=somevalue)

     return render(....)

And It's working, I am using the my_arg to filter the SomeForm's ModelChoiceField queryset via __init__ and my form looks like this:

class SomeForm(ModelForm):
   MyField = ModelChoiceField(queryset=SomeModel.objects.none())
    def __init__(self, *args, **kwargs):
        my_arg = kwargs.pop('my_arg', None)
        super(SomeForm, self).__init__(*args, **kwargs)
        self.fields['MyField'].queryset = SomeModel.objects.filter(fkey = my_arg)

And upon save I get <DjangoObject> is not JSON serializable error

Answer 1

You get this error because your inner form SomeForm does not receive my_arg as a parameter in kwargs . And because you use kwargs.pop('my_arg') without a default value -> you get a KeyError . If you use .pop with a default value provided ( kwargs.pop('my_arg', None) ) you wont get a KeyError .

If you really need to pass my_arg to your inner SomeForm take a look at this questions: here , here and here

UPDATE:

As far as I can see, you need my_arg to filter queryset of a field. Well you don't need to this at inner_form.__init__ , but after constructing all forms inside your formset.__init__ method.

Something like this:

class BaseFormSet(BaseInlineFormSet):
    def __init__(self, *args, **kwargs):
        my_arg = kwargs.pop("my_arg")
        super(BaseFormSet, self).__init__(*args, **kwargs)
        for form in self.forms:
            form.fields['my_field'].queryset = SomeModel.objects.filter(fkey = my_arg)