How to .update m2m field in django

Question

I have:

class MyUser(Model):
    today_ref_viewed_ips = ManyToManyField(
        UniqAddress, 
        related_name='today_viewed_users', 
        verbose_name="Adresses visited referal link today")
    ...

On some croned daily request I do:

for u in MyUser.objects.all():
    u.today_ref_viewed_ips.clear()

Can it be done on DB server with update?

MyUser.objects.all().update(...)

---

Ok, I can't update, thanks. But only thing I need is to TRUNCATE m2m internal table, is it possible to perform from django? How to know it's name whithout mysql's console "SHOW TABLES"?

Answer 1

If you want to update the m2m fields only and do not want to delete the m2m objects you can use the following:

#if you have **list of pk** for new m2m objects

today_ref_pk = [1,2,3]
u = MyUser.objects.get(pk=1)
u.today_ref_viewed_ips.clear()
u.today_ref_viewed_ips.add(*today_ref_pk)

for django >=1.11 documentation:

# if you have the **list of objects** for new m2m and you dont have the 
# issue of race condition, you can do the following:

today_ref_objs = [obj1, obj2, obj3]
u = MyUser.objects.get(pk=1)
u.today_ref_viewed_ips.set(today_ref_objs, clear=True)