old_contents: from django.db import models
  
  
  class PostQuerySet(models.QuerySet):
      def search(self, query):
          return self.filter(title__contains=query)
  
  
  class PostManager(models.Manager):
      def get_queryset(self):
          return PostQuerySet(self.model, using=self._db)
  
      def search(self, query):
          return self.get_queryset().search(query)
  
  
  class TimeStampedModel(models.Model):
      create_time = models.DateTimeField(auto_now_add=True)
  
      class Meta:
          abstract = True
  
new_contents: from django.db import models
  
  
  class PostQuerySet(models.QuerySet):
      def search(self, query):
          return self.filter(title__contains=query)
  
      def remain(self):
          return self.filter(is_deleted=False)
  
      def get_from_board(self, board):
          return self.filter(board=board)
  
  
  class PostManager(models.Manager):
      def get_queryset(self):
          return PostQuerySet(self.model, using=self._db)
  
      def search(self, query):
          return self.get_queryset().search(query)
  
      def remain(self):
          return self.get_queryset().remain()
  
      def get_from_board(self, board):
          return self.get_queryset().get_from_board(board)
  
  
  class TimeStampedModel(models.Model):
      create_time = models.DateTimeField(auto_now_add=True)
  
      class Meta:
          abstract = True
  
subject: Add PostManager and PostQuerySet