On Sun, 2009-01-11 at 00:11 -0800, juice wrote:
> > > I then figured it may run into a loop of saving the same model, so i
> > > was going to use signals but ran into the same issue that it would
> > > still need to be in the save function.
> >
> > Are you talking about the infinite loop problem here? I don't understand
> > this paragraph.
>
> Yes sir, after talking with webology, he also pointed out it would end
> up in an infinite loop. So i went looking into signals.
I think you may have thrown out the baby with the bathwater there. All
you should have to do is check if the location you retrieve is the same
as the current one and, if so, don't do the update. Like this:
def save(self, *args, **kwargs):
oa = Article.objects.filter(location=self.location)
if oa and oa[0] != self:
oa = oa(location=0)
oa.save()
super(Article, self).save(*args, **kwargs)
I've fixed a couple of other problems with your initial code. In
particular, if you're just inserting stuff into the normal save path,
you need to be able to handle the force_update and force_insert
arguments to save. Simplest way (since you don't care what the arguments
are) is to just pass through *args and **kwargs like I've done above.
You could even fine tune this a little bit by using a more specific
queryset (excluding the "self" element) and even using the update()
method. Behold the power of a fully operational Death Star ... er ...
here's a different way of writing it, I mean:
def save(self, *args, **kwargs):
Article.objects.filter(location=self.location).
exclude(pk=self.pk).update(location=0)
super(Article, self).save(*args, **kwargs)
Without testing it, I think that should work correctly even when self.pk
is None (i.e. when you haven't saved for the first time). If not, you
might need to not pass in the exclude() bit if self.pk is None, but test
that out.
> So with the help there and here, i moved onto signals.py. By trial and
> error, I hope to get going, but have run into a roadblock.
>
> If in the signals.py I put "from stories.models import Article", i
> receive ImportError: cannot import name Article. Now my reasoning
> behind this maybe wrong as well, so a little explanation there. I want
> to import the model so I can do my query on all objects to find the
> previous one with the old location...( or I think that is how I should
> handle it)
Since you don't show the code, and since my crystal ball is in for
repairs this year, it's hard to tell what is wrong with your code. :-)
My guess would be circular imports, which can be solved by not importing
Article directly, but by writing
from stories import models as story_models
def my_signal_handler(....):
story_models.Article.objects.filter(...) # etc...
I tend to import models from applications as something like
<app-name>_models as a habit these days, but you can drop the "as..."
bit if you're only importing that one application model file there.
See http://groups.google.com/group/django-users/msg/a9ab126db3341fd3 for
an explanation I wrote last week about this type of thing.
Still, signals feel like overkill for this situation. You've found the
infinite loop case, so just walk around it in the code. Don't break out
an entirely different shaped hammer.
Regards,
Malcolm
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