# Add a class to a form widget # Modify the default queryset of a foreign key fields

forms.py

def __init__(self, website, *args, **kwargs):
        self.website = website
        super(PageForm, self).__init__(*args, **kwargs)
        # Modify the default queryset of a foreign key fields
        self.fields["page_layout"].queryset = Layout.objects.filter(website=website)
        # Add a class to a form widget
        self.fields['page_layout'].widget.attrs['class'] = 'nc-popup-select'
        self.old_url = self.instance.url