Why is a ManyToMany reference automatically added to the model when a record is created?

Question

Django

Good day to all.

I have a problem with auto-adding a link when creating records in a model.
Model (slightly shortened - removed some of the fields so as not to lose the focus of the question):

class Marathon(models.Model):
    name = models.CharField(
        _("Name"),
        max_length=100,
    )
    creator = models.ForeignKey(
        "users.User",
        on_delete=models.CASCADE,
        related_name="owner",
        related_query_name="marathon_owner",
        verbose_name=_("Marathon creator"),
    )
    avatar = models.ForeignKey(
        "marathons.MarathonAvatar",
        verbose_name=_("Marathon avatar"),
        related_name="marathon",
        on_delete=models.SET_NULL,
        blank=True,
        null=True,
    )
    participants = models.ManyToManyField(
        "users.User",
        related_name="marathon",
        related_query_name="marathon_participants",
        verbose_name=_("Marathon participants"),
        blank=True,
    )

When a user creates a record, the user automatically becomes bound to the creator field (part of the code from the view):

request_data = self.request.POST
request_data._mutable = True
request_data['creator'] = request.user.id
serialization = self.serializer_class(data=request_data, context={'request': request})

But why is the same user automatically added to the participants field of the model? How to avoid it?

Answer 1

Try putting symmetrical=False in the ManyToManyField field