Recursion error calling a function using a post-save signal

Question

I have a Category model, where the ForeignKey is to self.

class Category(SEO, MetaData):
    parent = models.ForeignKey('self', blank=True, null=True, verbose_name='parent category', on_delete=models.CASCADE)
    path = ArrayField(models.IntegerField(), blank=True, null=True)

I introduced the path field, to avoid recursion in widget, and do it model, because is not often done.

I use a post_save signal to ssave the path:

def _recurse_for_parent(cat_obj, path=None):
    # path at the beginning don't exist and need to be initialized
    if not path:
        path = []
    if cat_obj.parent is not None:
        _recurse_for_parent(cat_obj.parent, path)
    return path


def save_path(sender, instance, **kwargs):
    if instance.parent_id:
        instance.children = _recurse_for_parent(instance.parent)
        instance.save()



post_save.connect(save_path, sender=Category)

My issue is that I get the "maximum recursion depth error" and I don't see why, because I use the condition:

cat_obj.parent is not None:

Answer 1

I found the error in def save_path I call instance.save(), which will trigger the post_save signal.

Because post_save signal calls save_path and save path calls save which trigger post_save, I'm entering in an infinite loop.

I solved by moving my logic to the save method.