How to modify form choices from class?

I have form class:

class Form(forms.ModelForm):
    id = forms.ModelChoiceField(queryset=Option.objects.all(), widget=forms.HiddenInput())
    category = forms.ModelChoiceField(queryset=Category.objects.all())

    class Meta:
        model = Option
        fields = ('id', 'category')

    def choices(self, ext_data):
        # something with extdata...
        choices = [('1','one')]
        category = forms.ModelChoiceField(queryset=choices)

but this:

my_form.choices(something)

is n开发者_运维问答ot working. Why?

I must implement this in class because i have one view and many different forms. Each form have specific choices function.

First, queryset must be a queryset, not a list, since you're using ModelChoiceField. Second, to reference the category form field use self.fields['category']. Your function should thus look something like this:

def choices(self, ext_data):  
    #I'm not sure what ext_data is, but I suspect it's something to filter the Categories
    self.fields['category'].queryset = Category.objects.filter(something=ext_data)

    #If ext_data itself is a queryset you can use it directly:
    self.fields['category'].queryset = ext_data

For clarification, a queryset is what you get when you use Model.objects.filter(xxx) or any other filtering action on your model.

Try to use init:

class MessageAdminForm(forms.ModelForm):
    def __init__(self, *arg, **kwargs):
        super(MessageAdminForm, self).__init__(*args, **kwargs)

        # set choices this way
        self.fields['field'].choices = [(g.id, g) for g in something]