'NoneType' object has no attribute 'tree_id'

[robslotboom]

Updating a root elements fiels which is the "order_insertion_by" raises:

'NoneType' object has no attribute 'tree_id'

I solved this bij adding two lines of code.

def _make_sibling_of_root_node(self, node, target, position):
    ...
    elif position == 'right':
        if target_tree_id > tree_id:
            new_tree_id = target_tree_id
            lower_bound, upper_bound = tree_id, target_tree_id
            shift = -1
        else:
            right_sibling = target.get_next_sibling()
            if node == right_sibling:
                return
            # Addition
            if not right_sibling:
                return
            # end of addition
            new_tree_id = getattr(right_sibling, self.tree_id_attr)
            lower_bound, upper_bound = new_tree_id, tree_id
            shift = 1

[matthiask]

Thank you for the report! Do you have some additional details such as the model itself? Will probably be a big help for constructing a test case.

[mullakhmetov]

I got the same error.
Environment: python 2.7.10, Django 1.9.1, django-mptt 0.8.4

# models.py
class Foo(MPTTModel):
    test = models.CharField(max_length=5)
    parent = TreeForeignKey('self', null=True, blank=True)

[matthiask]

Nice, now I can reproduce this, even without order_insertion_by.

It seems that setting parent_id does not reset parent in any way, resp. parent isn't dynamically loaded from the database just because the underlying id field has some value.

(As you have seen assigning parent directly works fine.)

[matthiask]

Additional testing reveals that this works:

f1 = Foo.objects.create()
f2 = Foo.objects.create()
f2.parent_id = f1.id
del f2._parent_cache  # Remove cached value of "None"
f2.save()