mixbacks.py

from django import forms
from localflavor.us.forms import USPSSelect


class NoDefaultSelect(forms.Select):
    def render_options(self, selected_choices):
        opts = super().render_options(selected_choices)
        if selected_choices:
            opts = "<option disabled selected value style='display:none;'></option>\n" + opts
        return opts


class NoDefaultUSPSSelect(USPSSelect, NoDefaultSelect):
    pass