Django Forms: Hidden model field?

Question

I\'ve got a Form. I want to include a hidden field that returns a model. I\'ll set it\'s value in the view; I just need it to be posted along to the next page.

Answer 1

A hidden field that returns a model? So a model instance ID?

The forms.HiddenInput widget should do the trick, whether on a FK field or CharField you put a model instance ID in.

class MyForm(forms.Form):
    hidden_2 = forms.CharField(widget=forms.HiddenInput())
    hidden_css = forms.CharField(widget=forms.MostWidgets(attrs={'style': 'display:none;'}))

I suppose the fastest way to get this working is

class MyForm(forms.Form):
    model_instance = forms.ModelChoiceField(queryset=MyModel.objects.all(), widget=forms.HiddenInput())

form = MyForm({'model_instance': '1'})
form.cleaned_data['model_instance']

But I don't like the idea of supplying MyModel.objects.all() if you're going to specify one item anyways.

It seems like to avoid that behavior, you'd have to override the form __init__ with a smaller QuerySet.

I think I prefer the old fashioned way:

class MyForm(forms.Form):
    model_instance = forms.CharField(widget=forms.HiddenInput())

    def clean_model_instance(self):
        data = self.cleaned_data['model_instance']
        if not data:
            raise forms.ValidationError()
        try:
            instance = MyModel.objects.get(id=data)
        except MyModel.DoesNotExist:
            raise forms.ValidationError()
        return instance