Ordering mptt tree using a field

Question

This is the original category model:

class Category(MPTTModel):
    name = models.CharField(max_length=50, unique=True)
    parent = TreeForeignKey('self', null=True, blank=True, related_name='children')

    def __unicode__(self):
        return self.name

    class MPTTMeta:
        order_insertion_by = ['name']

Then I needed to order the category, so I altered it like the following:

class Category(MPTTModel):
    name = models.CharField(max_length=50, unique=True)
    order = models.SmallIntegerField() <<<<<<<<<
    parent = TreeForeignKey('self', null=True, blank=True, related_name='children')

    def __unicode__(self):
        return self.name

    class MPTTMeta:
        order_insertion_by = ['order'] <<<<<<<<<

And I changed the Django admin declaration from:

admin.site.register(Category, MPTTModelAdmin)

To:

class CategoryAdmin(MPTTModelAdmin):
    list_display = ('name', 'order')
    list_editable = ('order',)


admin.site.register(Category, CategoryAdmin)

Then everything fall apart after making a few edits from the admin control panel. I can't describe exactly what happened but it seems the lft, rght, level and parent_id where messed up by these changes.

Am I using order_insertion_by in the wrong context? Is it for something else? I tried to search the docs but didn't get a useful answer.

Answer 1

I faced this problem. The problem is not in the package django-mptt, and in the framework Django, more precisely in the admin. Perhaps this is due to several administrators working simultaneously. While only one solution - to abandon the list_editable in admin class or write a script with the same field order for Ajax.

In order to restore the tree, use rebuld method: Category.tree.rebuild()