> Den 19. dec. 2015 kl. 16.01 skrev Aymeric Augustin
> <aymeric.augus...@polytechnique.org>:
>
> To be fair, this has a lot to do with MySQL’s lax approach to storing data.
> There’s so many situations where it just throws data away happily that one
> can’t really expect to read back data written to MySQL.
>
> That said, this change in Django sets up this trap for unsuspecting users.
> Providing a way for users to declare which fields use the old format won't
> work because of pluggable apps: they cannot know what version of MySQL their
> users were running when they first created a given datetime column. The best
> solution may be to provide a conversion script to upgrade all datetime
> columns from the old to the new format.
One simple solution could be for Christiano to subclass the DateTimeField to
handle the microsecond precision explicitly. Something like this to strip:
class DateTimeFieldWithPrecision(DateTimeField):
def __init__(self, *args, **kwargs):
self.precision = kwargs.get('precision', 6)
assert 0 <= self.precision <= 6
super().__init__(*args, **kwargs)
def pre_save(self, model_instance, add):
dt = getattr(model_instance, self.attname)
dt.replace(microsecond=int(dt.microsecond/10**(6-self.precision)))
return dt
Erik
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