Hey Victor, I can think that a trivial way (I am not sure if it is the best) to do that is to overwrite the save() method of your model:
class MyModel(models.Model):
title = models.CharField(max_length=100)
only_me = models.Boolean(default=False)
def save(self):
if self.only_me:
only_me_true = MyModel.objects.filter(only_me=True)
for obj in only_me_true:
obj.only_me = False
obj.save()
MyModel.save(self)
I would go for that solution. It is easy to implement, it seems clean and it
is easy to test as well.
Cheers dude!
Gabriel de Carvalho Nogueira Reis
Software Developer
+44 7907 823942
On Sat, Jan 16, 2010 at 12:22 AM, Victor Loureiro Lima <
victorloureirol...@gmail.com> 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?
>
> Thanks in Advance,
> Victor Lima
>
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