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

Query-1:

No, you cannot use .update() method to update a ManyToManyField.

Django's .update() method does not support ManyToManyField.

As per the docs from the section on updating multiple objects at once:

You can only set non-relation fields and ForeignKey fields using this method. To update a non-relation field, provide the new value as a constant. To update ForeignKey fields, set the new value to be the new model instance you want to point to.

Query-2:

If you want to delete all the objects of m2m table, you can use .delete() queryset method.

MyModel.objects.all().delete() # deletes all the objects

Another method is to execute the raw SQL directly. This method is faster than the previous one.

from django.db import connection
cursor = connection.cursor()
cursor.execute("TRUNCATE TABLE table_name")

Query-3:

To get the table name of a model, you can use db_table model Meta option.

my_model_object._meta.db_table # gives the db table name