Django: model has two ManyToMany relations through intermediate model

Question

So I am new to Django, and want to describe the scenario: there are a bunch of Persons, and there are a bunch of Items, and a person passes I

Answer 1

What you're describing sounds reasonable enough. There may be a technical reason why that's disallowed; one semantic reason is that each ManyToManyField implies the creation of a new table, and there can't be two tables with the same name (i.e. represented by the same class).

One alternative approach (shorter and more DRY) would be this:

class Person(models.Model): 
    name = models.CharField(max_length=127, blank=False)
    to_users = models.ManyToManyField(
        'self', 
        symmetrical=False, 
        related_name='from_users',
        through='Event', 
        through_fields=('from_user', 'to_user'),
    )

class Event(models.Model):
    item = models.ForeignKey(Item, related_name='events')
    from_user = models.ForeignKey(Person, related_name='events_as_giver')
    to_user = models.ForeignKey(Person, related_name='events_as_receiver')

The table structure is the same but the descriptors are different. Accessing related people is a bit easier but accessing related items is a bit harder (for example, instead of person.out_items.all() you would say Item.objects.filter(events__from_user=person).distinct()).