Added delete triggers to foreign keys

newsletters/models.py

@@ -18,11 +18,11 @@ class Attachment(models.Model):
 class Newsletter(models.Model):
     body = HTMLField()
     created = models.DateTimeField(auto_now_add=True)
-    creator = models.ForeignKey(User)
+    creator = models.ForeignKey(User, on_delete=models.DO_NOTHING)
     publish = models.DateTimeField(default=timezone.now)
     sent = models.BooleanField(default=False)
     subject = models.CharField(max_length=255)
-    attachments = models.ManyToManyField(Attachment)
+    attachments = models.ManyToManyField(Attachment, blank=True, null=True)
 
     def __str__(self):
         return self.subject