In what model should I add the ManyToManyField?

Question

I read the documentation about many-to-many relationships and the examples. What I could not find is a hint on where to put the ManyToManyField. In my case I have an extended user model Client and a model Pizza. Every client may mark one or more pizzas as favourites. Those are my two models:

from django.db import models
from django.contrib.auth.models import User

class Client(models.Model):
    user = models.OneToOneField(User)
    #? favourite_pizza = models.ManyToManyField()

class Pizza(models.Model):
    name = models.CharField(max_length=255)
    #? favourite_pizza = models.ManyToManyField()

In what model should I add the ManyToManyField? Does it matter?

PS The important information is how many favourite pizzas a client has (and which). It is less important how many clients marked a pizza as a favourite (and who). Consequently I would chose to put the ManyToManyField in the Client class.

Answer 1

From the Django documentation:

Generally, ManyToManyField instances should go in the object that’s going to be edited on a form.

Answer 2

Technically it does not matter. The question is from which model-side you will query the database.