old_contents: from django.db import models
  
  # Create your models here.
  class ItemPrefix(models.Model):
      itemprefix_name = models.CharField()
      itemprefix_flat_strength = models.IntegerField(default=0)
  class ItemType(models.Model):
      itemtype_name = models.CharField()
  class Item(models.Model):
      item_level = models.IntegerField(default=0)
      item_type = models.ForeignKey('ItemType')
      item_prefixes = models.ManyToManyField(ItemPrefix)
  
new_contents: from django.db import models
  
  # Create your models here.
  class ItemPrefix(models.Model):
      itemprefix_name = models.CharField(max_length=64)
      itemprefix_flat_strength = models.IntegerField(default=0)
  class ItemType(models.Model):
      itemtype_name = models.CharField(max_length=64)
  class Item(models.Model):
      item_level = models.IntegerField(default=0)
      item_type = models.ForeignKey('ItemType')
      item_prefixes = models.ManyToManyField(ItemPrefix)
  
subject: Update models.py