Ein Knoten kann kein Kind eines seiner Nachkommen in django MPTT

Question

hier ist die models.py

class Category(MPTTModel): 
      title = models.CharField(max_length =120) 
      name = models.CharField(max_length=120) 
      parent = models.ForeignKey('self' , null = True , blank = True ,  verbose_name='parent category', related_name='categories') 
      description = models.TextField(null=True , blank=True) 
      active = models.BooleanField(default=True) 
      slug = models.SlugField(blank=True) 
      timestamp = models.DateTimeField(auto_now_add=True , auto_now=False) 


      def get_absolute_url(self): 
        return reverse('categories', kwargs={'path': self.get_path()}) 



class Product(MPTTModel): 
      brand = models.ForeignKey(Brand , related_name='products') 
      category = models.ForeignKey('Category', verbose_name='categories', related_name='products' , default='') 
      parent = models.ForeignKey('self' , related_name = 'children' , null=True , blank=True) 
      title = models.CharField(max_length=500) 
      gender = models.CharField(max_length=10 , choices=GENDER_CHOICES) 
      SKU = models.CharField(max_length=255 , blank=True , unique=True) 
      description = models.TextField(max_length = 500 ,blank=True ,null=True) 
      price = models.IntegerField() 
      color = models.CharField(max_length=120) 
      discount = models.IntegerField(blank=True ,null =True) 
      active = models.BooleanField(default=True) 
      is_related = models.BooleanField(default=False) 
      is_combo = models.BooleanField(default=False) 
      is_verified = models.BooleanField(default=False) 
      in_stock = models.BooleanField(default=False) 
      slug = models.SlugField(max_length=255 , blank=True , unique=True) 
      timestamp = models.DateTimeField(auto_now_add=True,auto_now=False) 

      objects = ProductManager() 

      class Meta: 
        unique_together = ('SKU', 'slug', 'category', 'brand') 

      def __unicode__(self): 
       return self.title 

gemacht werden, wenn ich versuche, ein Produkt mit einigen Eltern, um es diesem Fehler wirft

A node may not be made a child of any of its descendants. 

hier ist die Zurückverfolgungs

Traceback: 

     File "C:\Python27\lib\site-packages\django\core\handlers\base.py" in get_response 
      132.      response = wrapped_callback(request, *callback_args, **callback_kwargs) 
     File "C:\Python27\lib\site-packages\django\contrib\admin\options.py" in wrapper 
      616.     return self.admin_site.admin_view(view)(*args, **kwargs) 
     File "C:\Python27\lib\site-packages\django\utils\decorators.py" in _wrapped_view 
      110.      response = view_func(request, *args, **kwargs) 
     File "C:\Python27\lib\site-packages\django\views\decorators\cache.py" in _wrapped_view_func 
      57.   response = view_func(request, *args, **kwargs) 
     File "C:\Python27\lib\site-packages\django\contrib\admin\sites.py" in inner 
      233.    return view(request, *args, **kwargs) 
     File "C:\Python27\lib\site-packages\django\contrib\admin\options.py" in add_view 
      1516.   return self.changeform_view(request, None, form_url, extra_context) 
     File "C:\Python27\lib\site-packages\django\utils\decorators.py" in _wrapper 
      34.    return bound_func(*args, **kwargs) 
     File "C:\Python27\lib\site-packages\django\utils\decorators.py" in _wrapped_view 
      110.      response = view_func(request, *args, **kwargs) 
     File "C:\Python27\lib\site-packages\django\utils\decorators.py" in bound_func 
      30.     return func.__get__(self, type(self))(*args2, **kwargs2) 
     File "C:\Python27\lib\site-packages\django\utils\decorators.py" in inner 
      145.      return func(*args, **kwargs) 
     File "C:\Python27\lib\site-packages\django\contrib\admin\options.py" in changeform_view 
      1467.     self.save_model(request, new_object, form, not add) 
     File "C:\Python27\lib\site-packages\django\contrib\admin\options.py" in save_model 
      1078.   obj.save() 
     File "C:\Python27\lib\site-packages\mptt\models.py" in save 
      973.    super(MPTTModel, self).save(*args, **kwargs) 
     File "C:\Python27\lib\site-packages\django\db\models\base.py" in save 
      710.      force_update=force_update, update_fields=update_fields) 
     File "C:\Python27\lib\site-packages\django\db\models\base.py" in save_base 
      747.         update_fields=update_fields, raw=raw, using=using) 
     File "C:\Python27\lib\site-packages\django\dispatch\dispatcher.py" in send 
      201.    response = receiver(signal=self, sender=sender, **named) 
     File "C:\Users\lenovo\Desktop\Grooved2\grooved\src\products\models.py" in product_post_save_receiver 
      403.   instance.save() 
     File "C:\Python27\lib\site-packages\mptt\models.py" in save 
      918.         self, parent, 'last-child', save=False) 
     File "C:\Python27\lib\site-packages\mptt\managers.py" in _move_node 
      576.      self._move_root_node(node, target, position) 
     File "C:\Python27\lib\site-packages\mptt\managers.py" in _move_root_node 
      1190.    raise InvalidMove(_('A node may not be made a child of any of its descendants.')) 

     Exception Type: InvalidMove at /admin/products/product/add/ 
     Exception Value: A node may not be made a child of any of its descendants. 

wie kann ich den oben problem.thanks im Voraus

lösen

Answer 1

Es hängt davon ab, welche Version von django-mptt Sie verwenden. Meine Lösung wäre:

class Category(MPTTModel): 
    # Other Fields 
    parent = TreeForeignKey(
      'self', null=True, blank=True, related_name='children', 
      verbose_name=pgettext_lazy('Category field', 'parent')) 

oder

from mptt.managers import TreeManager 
class Category(MPTTModel): 
    # Other Fields 
    parent = models.ForeignKey(
     'self', null=True, blank=True, related_name='children', 
     verbose_name=pgettext_lazy('Category field', 'parent')) 
    objects = Manager() 
    tree = TreeManager()