Error accesing reverse manytomany field from user to onetoone related model-CodePudding

Im having trouble with a model classs which has a onetoone relation with the User model, this the conflictive part:

class UserInteraction(models.Model):
    user = models.OneToOneField(User, related_name="interactions", on_delete=models.CASCADE)

    users_follows = models.ManyToManyField('self', through='UserFollow', blank=True, symmetrical=False, related_name='user_follows')
    users_likes = models.ManyToManyField('self', through='UserLike', blank=True, symmetrical=False, related_name='user_likes')

When I try to get the follows/likes by doing user.interactions.user_follows or user.interactions.user_likes I get the following error:

In [18]: u = User.objects.get(id=1)

In [19]: u.interactions.users_likes.all()
---------------------------------------------------------------------------
AttributeError                            Traceback (most recent call last)
Input In [19], in <module>
----> 1 u.interactions.users_likes.all()

File ~\...\django\db\models\fields\related_descriptors.py:536, in ReverseManyToOneDescriptor.__get__(self, instance, cls)
    533 if instance is None:
    534     return self
--> 536 return self.related_manager_cls(instance)

File ~\...\django\db\models\fields\related_descriptors.py:826, in create_forward_many_to_many_manager.<locals>.ManyRelatedManager.__init__(self, instance)
    824     self.prefetch_cache_name = rel.field.name
    825     self.source_field_name = rel.field.m2m_field_name()
--> 826     self.target_field_name = rel.field.m2m_reverse_field_name()
    827     self.symmetrical = rel.symmetrical
    828 else:

File ~\...\django\db\models\fields\related.py:1598, in ManyToManyField._get_m2m_reverse_attr(self, related, attr)
   1596             setattr(self, cache_attr, getattr(f, attr))
   1597             break
-> 1598 return getattr(self, cache_attr)

AttributeError: 'ManyToManyField' object has no attribute '_m2m_reverse_name_cache'

Here is the follower and like models used for through in the fk:

class UserFollow(TimeStampBase):
    follower = models.ForeignKey(User, on_delete=models.CASCADE, related_name='follower')
    followed = models.ForeignKey(User, on_delete=models.CASCADE, related_name='followed')

    class Meta:
        constraints = [
            models.UniqueConstraint(
                name="%(app_label)s_%(class)s_unique_relationships",
                fields=["followed", "follower"],
            ),
            models.CheckConstraint(
                name="%(app_label)s_%(class)s_prevent_self_follow",
                check=~models.Q(follower=models.F("followed")),
            ),
        ]

    def __str__(self):
        return f'{self.follower} follows {self.followed}'


class UserLike(TimeStampBase):
    liker = models.ForeignKey(User, on_delete=models.CASCADE, related_name='liker')
    liked = models.ForeignKey(User, on_delete=models.CASCADE, related_name='liked')

    class Meta:
        constraints = [
            models.UniqueConstraint(
                name="%(app_label)s_%(class)s_unique_relationships",
                fields=["liked", "liker"],
            ),
            models.CheckConstraint(
                name="%(app_label)s_%(class)s_prevent_self_follow",
                check=~models.Q(liker=models.F("liked")),
            ),
        ]

    def __str__(self):
        return f'{self.liker} likes {self.liked}'

In the admin everything works fine, what im doing wrong?

CodePudding user response：

The ForeignKey fields in through models need to reference the model that contains the ManyToManyField and not the model in the OneToOneField - UserInteraction and not User

class UserFollow(TimeStampBase):
    follower = models.ForeignKey(UserInteraction, on_delete=models.CASCADE, related_name='follower')
    followed = models.ForeignKey(UserInteraction, on_delete=models.CASCADE, related_name='followed')
    ...

class UserLike(TimeStampBase):
    liker = models.ForeignKey(UserInteraction, on_delete=models.CASCADE, related_name='liker')
    liked = models.ForeignKey(UserInteraction, on_delete=models.CASCADE, related_name='liked')
    ...