add message and comment

announcement/models.py

@@ -1,7 +1,6 @@
 from django.db import models
 
 from account.models import User
-from submission.models import Submission
 from utils.models import RichTextField
 
 
@@ -19,15 +18,3 @@ class Announcement(models.Model):
     class Meta:
         db_table = "announcement"
         ordering = ("-top", "-create_time",)
-
-
-class Message(models.Model):
-    sender = models.ForeignKey(User, on_delete=models.CASCADE, related_name="sender")
-    recipient = models.ForeignKey(User, on_delete=models.CASCADE, related_name="recipient")
-    submission = models.ForeignKey(Submission, on_delete=models.CASCADE)
-    message = RichTextField()
-    create_time = models.DateTimeField(auto_now_add=True)
-
-    class Meta:
-        db_table = "message"
-        ordering = ("-create_time",)