On Wed, Feb 15, 2012 at 12:37 AM, Marc Aymerich <glicer...@gmail.com> wrote: > On Tue, Feb 14, 2012 at 8:02 PM, Jeff Blaine <cjbla...@gmail.com> wrote: >> Hi all, >> >> I'm having trouble detecting changes that happen to a M2M field behind the >> scenes: as a result of one of the *referenced objects being deleted* >> >> I'm using Django 1.3.1 with PostgreSQL 8 >> >> Let's say we have the following simple proof of concept models: >> >> class Topping(models.Model): >> name = models.CharField() >> >> class Pizza(models.Model): >> name = models.CharField() >> toppings = models.ManyToManyField(Topping, null=true, blank=true) >> >> And this data established using those models: >> >> TOPPING >> id=1, name="Pepperoni"> Register a post_delete signal for Topping? How >> do I refer to or find the >> id=2, name="Onion" >> id=3, name="Mushroom" >> >> PIZZA >> id=1, name="foopizza" >> toppings=1,2,3 >> >> Known Facts: >> >> 1. Deleting any Topping object (for example, deleting id=1, >> name="Pepperoni") also removes it from foopizza.toppings. Good. >> 2. No m2m_changed signal is sent when 1 (above happens). BAD. >> >> How do I tie into "topping *object* was deleted (no longer for sale), >> perform custom code on ALL Pizza objects that referenced it" ? >> >> Register a post_delete signal for Topping? How do I refer to or find the >> Pizza objects that referred to it? >> > > You can introspect topping model looking for pizza m2m relation-like: > take a look at Topping._meta attribute, and then send a custom signal > for each related objects when a topping is deleted.
Check this out ;) https://docs.djangoproject.com/en/dev/ref/signals/#m2m-changed -- Marc -- You received this message because you are subscribed to the Google Groups "Django users" group. To post to this group, send email to django-users@googlegroups.com. To unsubscribe from this group, send email to django-users+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/django-users?hl=en.
