title: In what model should I add the ManyToManyField?
body: <p>I read the <a href="https://docs.djangoproject.com/en/dev/ref/models/fields/#ref-manytomany" rel="noreferrer">documentation about many-to-many relationships</a> and the <a href="https://docs.djangoproject.com/en/dev/topics/db/examples/many_to_many/" rel="noreferrer">examples</a>. What I could not find is a hint on where to put the <em>ManyToManyField</em>. In my case I have an extended user model <em>Client</em> and a model <em>Pizza</em>. Every client may mark one or more pizzas as favourites. Those are my two models:</p>
  
  <pre><code>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()
  </code></pre>
  
  <p><strong>In what model should I add the ManyToManyField?</strong> Does it matter?</p>
  
  <p>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 <em>ManyToManyField</em> in the <em>Client</em> class.</p>