Why not simple fetch `old version` of object from database and compare its
fields. For example:
def save(self, *args, **kwargs):
if self._get_pk_val():
old = self.__class__.objects.get(pk=self._get_pk_val()
for field in self.__class__._meta.fields:
old_value = field._get_val_from_obj(old)
current_value = field._get_val_from_obj(self)
if old_value != current_value:
#do something fun here
super(self.__class__, self).save(*args, **kwargs)
On Mon, Nov 10, 2008 at 22:03, Tim <[EMAIL PROTECTED]> wrote:
>
> Basically, I want to be able to do something if the value of a field
> changes in a model.
>
> c = Category.objects.get(pk=1)
> c.name = "New Name"
> c.save()
>
> At any point (when the model is saved, when the value is set, etc.) is
> it possible to compare the old and new value? The first thought that
> popped into my head was something like this. I know this exact code
> isn't possible, it's just an example of what I'm trying to do.
>
> class Category(models.Models):
>
> def save(self):
> if self.name.old_value != self.name.value:
> do something fun here
> super(Category, self).save()
>
> If something like this isn't built in to Django, I was thinking of
> writing a custom field and overwriting __set__() to store the old
> value somewhere, since that seems to be the only place that would have
> access to the new and old value.
>
> Any thoughts on whether that's the best method?
>
> >
>
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