Yes No boolean field for

fields.py

from django import forms

class YesNoNullBooleanSelect(forms.Select):
    """
    A Select Widget intended to be used with YesNoBooleanField.
    """

    def value_from_datadict(self, data, files, name):
        value = data.get(name, None)
        return {u'2': True,
                True: True,
                'True': True,
                'yes': True,
                u'3': False,
                'False': False,
                'no': False,
                False: False}.get(value, None)

class YesNoBooleanField(forms.NullBooleanField):
    """
    A field whose valid values are None, True and False. Invalid values are
    cleaned to None.
    """
    widget = YesNoNullBooleanSelect

    def to_python(self, value):
        if value in (True, 'True', '1', 'yes'):
            return True
        elif value in (False, 'False', '0', 'no'):
            return False
        else:
            return None