fix: Preserve author_username and retired_username during MongoDB to …

forum/backends/mysql/api.py

@@ -1223,12 +1223,16 @@ def retire_all_content(
         comments = Comment.objects.filter(author__pk=user_id)
         for comment in comments:
             comment.body = RETIRED_BODY
+            comment.retired_username = username
+            comment.author_username = username
             comment.save()
 
         comment_threads = CommentThread.objects.filter(author__pk=user_id)
         for comment_thread in comment_threads:
             comment_thread.body = RETIRED_BODY
             comment_thread.title = RETIRED_TITLE
+            comment_thread.retired_username = username
+            comment_thread.author_username = username
             comment_thread.save()
 
     @staticmethod
@@ -1949,6 +1953,10 @@ def replace_username_in_all_content(user_id: str, username: str) -> None:
             user = User.objects.get(pk=user_id)
             user.username = username
             user.save()
+
+            # Update author_username in all content
+            Comment.objects.filter(author=user).update(author_username=username)
+            CommentThread.objects.filter(author=user).update(author_username=username)
         except User.DoesNotExist as exc:
             raise ValueError("User does not exist") from exc
 

forum/backends/mysql/models.py

@@ -96,6 +96,18 @@ class Content(models.Model):
     author: models.ForeignKey[User, User] = models.ForeignKey(
         User, on_delete=models.CASCADE
     )
+    author_username: models.CharField[Optional[str], str] = models.CharField(
+        max_length=255,
+        null=True,
+        blank=True,
+        help_text="Username at time of posting, preserved for historical accuracy",
+    )
+    retired_username: models.CharField[Optional[str], str] = models.CharField(
+        max_length=255,
+        null=True,
+        blank=True,
+        help_text="Username to display if author account was retired",
+    )
     course_id: models.CharField[str, str] = models.CharField(max_length=255)
     body: models.TextField[str, str] = models.TextField()
     visible: models.BooleanField[bool, bool] = models.BooleanField(default=True)
@@ -184,6 +196,16 @@ def get_votes(self) -> dict[str, Any]:
             votes["count"] = votes["count"]
         return votes
 
+    def save(self, *args: Any, **kwargs: Any) -> None:
+        """Set author_username on creation if not already set."""
+        if not self.pk and not self.author_username:
+            # On creation, store the current username
+            if self.retired_username:
+                self.author_username = self.retired_username
+            elif self.author:
+                self.author_username = self.author.username
+        super().save(*args, **kwargs)
+
     def to_dict(self) -> dict[str, Any]:
         """Return a dictionary representation of the content."""
         raise NotImplementedError
@@ -288,7 +310,9 @@ def to_dict(self) -> dict[str, Any]:
             "closed_by_id": str(self.closed_by.pk) if self.closed_by else None,
             "close_reason_code": self.close_reason_code,
             "author_id": str(self.author.pk),
-            "author_username": self.author.username,
+            "author_username": self.author_username
+            or self.retired_username
+            or self.author.username,
             "updated_at": self.updated_at,
             "created_at": self.created_at,
             "last_activity_at": self.last_activity_at,
@@ -469,7 +493,9 @@ def to_dict(self) -> dict[str, Any]:
             "author_id": str(self.author.pk),
             "comment_thread_id": str(self.comment_thread.pk),
             "child_count": self.child_count,
-            "author_username": self.author.username,
+            "author_username": self.author_username
+            or self.retired_username
+            or self.author.username,
             "sk": str(self.pk),
             "updated_at": self.updated_at,
             "created_at": self.created_at,

forum/migration_helpers.py

@@ -91,13 +91,29 @@ def create_or_update_thread(thread_data: dict[str, Any]) -> None:
     author = get_user_or_none(thread_data["author_id"])
     if not author:
         return
+
+    # Preserve author_username from MongoDB (historical username)
+    author_username = thread_data.get("author_username")
+
+    # Preserve retired_username from MongoDB
+    retired_username = thread_data.get("retired_username")
+
+    # If author_username is not provided, use retired_username or fallback to current username
+    if not author_username:
+        if retired_username:
+            author_username = retired_username
+        else:
+            author_username = author.username
+
     mongo_thread_id = str(thread_data["_id"])
     mongo_content, _ = MongoContent.objects.get_or_create(
         mongo_id=mongo_thread_id,
     )
     if not mongo_content.content_object_id:
         thread = CommentThread.objects.create(
             author=author,
+            author_username=author_username,
+            retired_username=retired_username,
             course_id=thread_data["course_id"],
             title=get_trunc_title(thread_data.get("title", "")),
             body=thread_data["body"],
@@ -128,6 +144,20 @@ def create_or_update_comment(comment_data: dict[str, Any]) -> None:
     author = get_user_or_none(comment_data["author_id"])
     if not author:
         return
+
+    # Preserve author_username from MongoDB (historical username)
+    author_username = comment_data.get("author_username")
+
+    # Preserve retired_username from MongoDB
+    retired_username = comment_data.get("retired_username")
+
+    # If author_username is not provided, use retired_username or fallback to current username
+    if not author_username:
+        if retired_username:
+            author_username = retired_username
+        else:
+            author_username = author.username
+
     mongo_thread_id = str(comment_data["comment_thread_id"])
     mongo_thread = MongoContent.objects.filter(mongo_id=mongo_thread_id).first()
     if not mongo_thread:
@@ -169,6 +199,8 @@ def create_or_update_comment(comment_data: dict[str, Any]) -> None:
     if not mongo_comment.content_object_id:
         comment = Comment.objects.create(
             author=author,
+            author_username=author_username,
+            retired_username=retired_username,
             comment_thread=thread,
             parent=parent,
             course_id=comment_data["course_id"],

forum/migrations/0004_add_author_username_fields.py

@@ -0,0 +1,43 @@
+# Generated by Django 4.2 on 2024-10-24 13:36
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ("forum", "0003_alter_commentthread_title"),
+    ]
+
+    operations = [
+        migrations.AddField(
+            model_name="comment",
+            name="author_username",
+            field=models.CharField(
+                blank=True,
+                help_text="Username at time of posting, preserved for historical accuracy",
+                max_length=255,
+                null=True,
+            ),
+        ),
+        migrations.AddField(
+            model_name="commentthread",
+            name="author_username",
+            field=models.CharField(
+                blank=True,
+                help_text="Username at time of posting, preserved for historical accuracy",
+                max_length=255,
+                null=True,
+            ),
+        ),
+        migrations.AddField(
+            model_name="commentthread",
+            name="retired_username",
+            field=models.CharField(
+                blank=True,
+                help_text="Username to display if author account was retired",
+                max_length=255,
+                null=True,
+            ),
+        ),
+    ]