def formfield(self, **kwargs):
        """Gets the form field associated with this field.

        Because this is a slug field which is automatically
        populated, it should be hidden from the form.
        """

        defaults = {
            'form_class': forms.CharField,
            'required': False
        }

        defaults.update(kwargs)

        form_field = super().formfield(**defaults)
        form_field.widget = forms.HiddenInput()

        return form_field