SeparatedValuesField for Django

list_field.py

class SeparatedValuesField(models.TextField):
    """
    Usage:
        class Foo(models.Model):
            bar = SeparatedValuesField()

        _list = [1, '2', date.today()]
        obj = Foo.objects.create(bar=_list)
        assert obj.bar == _list
    """

    __metaclass__ = models.SubfieldBase

    def __init__(self, *args, **kwargs):
        self.token = kwargs.pop('token', ',')
        self.date_format = kwargs.pop('date_format', "%d/%m/%Y")
        super(SeparatedValuesField, self).__init__(*args, **kwargs)

    def to_python(self, value):
        dt_str = lambda dt: datetime.strptime(dt, self.date_format).date()
        if not value:
            return
        if isinstance(value, list):
            return value
        _list = []
        for x in value.split(self.token):
            try:
                _list.append(dt_str(x))
            except ValueError:
                if x.isdigit():
                    _list.append(int(x))
                else:
                    _list.append(x)
        return _list

    def get_db_prep_value(self, value, connection, prepared=False):
        if not value:
            return
        _list = []
        for _str in value:
            if isinstance(_str, date):
                _str = _str.strftime(self.date_format)
            elif _str is None:
                _str = ''
            _list.append(unicode(_str))

        return self.token.join(_list)

    def value_to_string(self, obj):
        value = self._get_val_from_obj(obj)
        return self.get_db_prep_value(value)