Django ModelChoiceField, validation for dynamic queryset

Question

I have this current form:

class PersonForm(forms.Form):                                                                                           
    article = forms.CharField(required=False)
    workshop = forms.ModelChoiceField(queryset=Program.objects.none(),
                                      empty_label="----",
                                      required=False,
                                      label='Atelier')

    def __init__(self, *args, **kwargs):                                                                                    
        super(PersonForm, self).__init__(*args, **kwargs)
        article = self.initial.get('article', None)
        if article:
            a = Article.objects.get(pk=article)
            if a.workshop:
                self.fields['workshop'].queryset = Program.objects.filter(event=a.event, workshop=True)
                self.fields['workshop'].required = True
                self.helper.layout.insert(4, Row1Field('workshop',))

The queryset used to retrieve all the workshops is dynamic, so the queryset attribute inside the ModelChoiceField is set to Program.objects.none() , and the dynamic queryset is done inside the form's __init__ method

Everything is working fine: all the values displayed for workshop inside the select are ok. But when I post the form, there is a validation error: 'Select a valid choice. This choice is not among available choices.' 'Select a valid choice. This choice is not among available choices.'

Is there something I'm missing?

Answer 1

Depending on the code that is instantiating the form upon post, initial may not be passed. You could try:

article = self.initial.get('article', None) or self.data.get('article', None)

This will get the pk from your form POST data.