من مدل را طبق استاد برنامه نوشتم الان python manage.py میخواهم اجرا کنم خطا می‌دهد و با کامنت کردن مدل مون python manage.pyاجرا میشه

attribute_type = models.PositiveSmallIntegerField(default=INTEGER,choices=ATTRIBUTE_TYPES_FIELDS)

این را خطا میده

class Product(models.Model):
    product_Type = models.ForeignKey(ProductType, on_delete=models.PROTECT, related_name='products_types')
    upc = models.BigIntegerField(unique=True)
    title = models.CharField(max_length=32)
    description = models.TextField(blank=True)
    Category = models.ForeignKey(Category, on_delete=models.PROTECT, related_name='products_cat')
    brand = models.ForeignKey(Category, on_delete=models.PROTECT, related_name='products_brand')
def __str__(self):
    return self.title

def __str__(self):
    return self.title
class ProductAttributeValue(models.Model):
    product = models.ForeignKey(Product, on_delete=models.CASCADE, related_name='attribute_values')
    value = models.CharField(max_length=48)
    attribute = models.ForeignKey(ProductAttribute, on_delete=models.PROTECT, related_name='values')
    def __str__(self):
        return f"{self.product}({self.attribute}):{self.value}"

این دو کلاس ام مشکل داره چون این‌ها را کامنت میکنم اجرا میشه

python manage.py

خطا در ترمینال چاپ میکنه

Traceback (most recent call last):
 File "/home/mahdiyousfi/Academy/venv/lib/python3.10/site-packages/django/db/models/fields/related.py", line 798, in __init__
  to._meta.model_name
AttributeError: 'ForeignKey' object has no attribute '_meta'
During handling of the above exception, another exception occurred:
Traceback (most recent call last):
 File "/home/mahdiyousfi/Academy/academy/manage.py", line 22, in 
  main()
 File "/home/mahdiyousfi/Academy/academy/manage.py", line 18, in main
  execute_from_command_line(sys.argv)
 File "/home/mahdiyousfi/Academy/venv/lib/python3.10/site-packages/django/core/management/__init__.py", line 419, in execute_from_command_line
  utility.execute()
 File "/home/mahdiyousfi/Academy/venv/lib/python3.10/site-packages/django/core/management/__init__.py", line 395, in execute
  django.setup()
 File "/home/mahdiyousfi/Academy/venv/lib/python3.10/site-packages/django/__init__.py", line 24, in setup
  apps.populate(settings.INSTALLED_APPS)
 File "/home/mahdiyousfi/Academy/venv/lib/python3.10/site-packages/django/apps/registry.py", line 114, in populate
  app_config.import_models()
 File "/home/mahdiyousfi/Academy/venv/lib/python3.10/site-packages/django/apps/config.py", line 301, in import_models
  self.models_module = import_module(models_module_name)
 File "/usr/lib/python3.10/importlib/__init__.py", line 126, in import_module
  return _bootstrap._gcd_import(name[level:], package, level)
 File "", line 1050, in _gcd_import
 File "", line 1027, in _find_and_load
 File "", line 1006, in _find_and_load_unlocked
 File "", line 688, in _load_unlocked
 File "", line 883, in exec_module
 File "", line 241, in _call_with_frames_removed
 File "/home/mahdiyousfi/Academy/academy/catalogue/models.py", line 49, in 
  class Product(models.Model):
 File "/home/mahdiyousfi/Academy/academy/catalogue/models.py", line 56, in Product
  brand = models.ForeignKey(Category, on_delete=models.PROTECT, related_name='products_brand')
 File "/home/mahdiyousfi/Academy/venv/lib/python3.10/site-packages/django/db/models/fields/related.py", line 800, in __init__
  assert isinstance(to, str), (
AssertionError: ForeignKey() is invalid. First parameter to ForeignKey must be either a model, a model name, or the string 'self'