Method to_python

django/db/models/fields/__init__.py:1637–1688

(self, value)

        return "DateTimeField"

    def to_python(self, value):
        if value is None:
            return value
        if isinstance(value, datetime.datetime):
            return value
        if isinstance(value, datetime.date):
            value = datetime.datetime(value.year, value.month, value.day)
            if settings.USE_TZ:
                # For backwards compatibility, interpret naive datetimes in
                # local time. This won't work during DST change, but we can't
                # do much about it, so we let the exceptions percolate up the
                # call stack.
                try:
                    name = f"{self.model.__name__}.{self.name}"
                except AttributeError:
                    name = "(unbound)"
                warnings.warn(
                    f"DateTimeField {name} received a naive datetime ({value}) while "
                    "time zone support is active.",
                    RuntimeWarning,
                )
                default_timezone = timezone.get_default_timezone()
                value = timezone.make_aware(value, default_timezone)
            return value

        try:
            parsed = parse_datetime(value)
            if parsed is not None:
                return parsed
        except ValueError:
            raise exceptions.ValidationError(
                self.error_messages["invalid_datetime"],
                code="invalid_datetime",
                params={"value": value},
            )

        try:
            parsed = parse_date(value)
            if parsed is not None:
                return datetime.datetime(parsed.year, parsed.month, parsed.day)
        except ValueError:
            raise exceptions.ValidationError(
                self.error_messages["invalid_date"],
                code="invalid_date",
                params={"value": value},
            )

        raise exceptions.ValidationError(
            self.error_messages["invalid"],
            code="invalid",
            params={"value": value},
        )

    def pre_save(self, model_instance, add):
        if self.auto_now or (self.auto_now_add and add):