class Message(models.Model): 
  src_user = models.ForeignKey(User,related_name='src_users',) 
  dst_user = models.ForeignKey(User,related_name='dst_users',) 
  dst_read = models.BooleanField(default=False) 
  src_delete = models.BooleanField(default=False) 
  dst_delete = models.BooleanField(default=False) 
  subject = models.CharField(maxlength=255) 
  content = models.TextField(maxlength=5000) 
  time = models.DateTimeField(default=datetime.now)