On Jan 15, 2010, at 4:22 PM, Victor Loureiro Lima wrote:
> Here is the deal:
>
> class MyModel ( models.Model ):
> title = models.CharField( max_length = 100 )
> only_me = models.BooleanField( default = False )
>
> Question: Whats the proper way to guarantee that no matter how many
> MyModel's are available in the database, only one of them
> will have the only_me set as True? To further clarify things: In the admin,
> whenever I check the only_me checkbox, and save my model, all other models of
> this class will have to have its own only_me field set to false.
>
> As far as I know, there is no other way of doing this unless I iterate over
> all MyModel' s objects and uncheck them if they are checked, save them, then
> afterwards check the model that I am actually saving setting the only_me
> field to True.
>
> I tried doing this on the actual save() of the model, no success. Everytime
> I called save on iterated objects, I, of course, got the maximum recursive
> depth error thrown at me.
> Fair enough, I quickly thought about signals, hooking my function to
> post_save(), however I inevitabilly stumbled upon the same
> problem: When I called save() on the iterated objects the post_save signal
> got sent, I would step again in the same function, thus
> no cookie for me.
> I jumped over to overriding AdminForm' s save() method, so that I would
> iterate there on the models unchecking them if necessary, and them returning
> the proper object, but I stopped that and I said to myself that I must be
> doing something really stupid, so Im coming to you guys: What would the
> propper way of doing this?
>
def save(self, force_insert=False, force_update=False):
if self.only_me is True:
# if this is the new default, set others to False
MyModel.objects.exclude(pk=self.pk).update(only_me=False)
super(MyModel, self).save(force_insert, force_update) # Call the "real"
save() method.
--
Eric Chamberlain, Founder
RF.com - http://RF.com/
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