feat: added soft delete functionality #10

Alam-2U · 2026-01-12T10:24:11Z

Description

Implements soft delete functionality for discussion threads, responses, and comments using the is_deleted flag instead of permanently deleting records.
This enables safe deletion and restoration of discussion content while preserving existing data.

Changes Made

Added soft delete and restore functionality for threads, responses, and comments.
Introduced support to view deleted content in the Learner tab using a new Active / Deleted filter.
Implemented restore actions for deleted threads, responses, and comments.
Added deleted count tracking and support for sorting by deleted count in the Learner tab.
Implemented bulk delete and bulk restore actions for discussion content.
Ensured nested responses and comments are handled correctly during delete and restore operations.
Added API support to fetch deleted content for moderation workflows.

Note:
Features listed above (except soft delete itself) are available only to Staff, Admins, Moderators, and TAs.

JIRA Tickets

COSMO2-742 – Link
COSMO2-769 – Link
COSMO2-783 – Link
COSMO2-793 – Link

Related Pull Requests

Merge checklist:
Check off if complete or not applicable:

Version bumped
Documentation updated (not only docstrings)
Fixup commits are squashed away
Unit tests added/updated

Copilot

Pull request overview

This PR implements soft delete functionality for discussion threads, responses, and comments using an is_deleted flag. Instead of permanently removing records, content is marked as deleted and can be restored later. The implementation includes deleted content tracking in user statistics, filtering capabilities, and bulk restore operations for privileged users.

Changes:

Added soft delete fields (is_deleted, deleted_at, deleted_by) to threads and comments with database migration
Implemented soft delete and restore operations across MySQL and MongoDB backends with stat tracking
Added API endpoints to view and restore deleted content, plus filtering support in search and user queries

Reviewed changes

Copilot reviewed 19 out of 19 changed files in this pull request and generated 23 comments.

Show a summary per file

File	Description
forum/init.py	Version bumped to 0.4.0
forum/migrations/0006_comment_deleted_at_comment_deleted_by_and_more.py	Database migration adding soft delete fields to Comment and CommentThread models
forum/backends/mysql/models.py	Added soft delete fields and updated comment_count to exclude deleted comments
forum/backends/mysql/api.py	Implemented soft delete/restore logic, stat tracking, and deleted content queries for MySQL
forum/backends/mongodb/threads.py	Added soft delete/restore methods and deleted content queries for threads
forum/backends/mongodb/comments.py	Modified delete method to support soft delete mode and added restore functionality
forum/backends/mongodb/api.py	Implemented soft delete orchestration, stat updates, and deleted content filtering
forum/backends/backend.py	Added abstract methods for deleted content retrieval
forum/serializers/contents.py	Added serializer fields for soft delete metadata
forum/api/threads.py	Updated delete_thread to use soft delete and added restore endpoints
forum/api/comments.py	Updated delete_comment to use soft delete and added restore endpoints
forum/api/users.py	Added show_deleted parameter for viewing deleted threads in user stats
forum/api/search.py	Added is_deleted parameter to search functionality
forum/api/init.py	Exported new deleted content retrieval functions
forum/views/comments.py	Updated documentation for delete endpoint
tests/test_views/test_threads.py	Updated assertions to check for soft delete instead of hard delete
tests/test_views/test_comments.py	Updated assertions and added documentation about soft delete behavior
tests/test_backends/test_mongodb/test_comments.py	Updated expected return values for delete method
tests/e2e/test_users.py	Added deleted content stats and updated test assertions

Comments suppressed due to low confidence (1)

forum/api/init.py:95

The restore_comment, restore_user_deleted_comments, restore_thread, and restore_user_deleted_threads functions are imported but not included in the all list. This means they won't be exported when someone does "from forum.api import *". Either add them to all or remove the unused imports if they're meant to be internal-only functions.

__all__ = [
    "create_child_comment",
    "create_parent_comment",
    "create_subscription",
    "create_thread",
    "create_user",
    "delete_comment",
    "delete_comment_vote",
    "delete_subscription",
    "delete_thread",
    "delete_thread_vote",
    "get_commentables_stats",
    "get_course_id_by_comment",
    "get_course_id_by_thread",
    "get_parent_comment",
    "get_thread",
    "get_thread_subscriptions",
    "get_user",
    "get_user_active_threads",
    "get_user_comments",
    "get_user_course_stats",
    "get_user_subscriptions",
    "get_user_threads",
    "get_deleted_comments_for_course",
    "get_deleted_threads_for_course",
    "mark_thread_as_read",
    "pin_thread",
    "retire_user",
    "search_threads",
    "unpin_thread",
    "update_comment",
    "update_comment_flag",
    "update_comment_votes",
    "update_thread",
    "update_thread_flag",
    "update_thread_votes",
    "update_user",
    "update_username",
    "update_users_in_course",
]

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Copilot · 2026-01-13T06:43:19Z

forum/backends/mongodb/api.py

+                # Update existing fields and add new fields if they don't exist
+                for k, v in kwargs.items():
+                    course_stat[k] = course_stat.get(k, 0) + v


The update_stats_for_course method in MongoDB has been modified to add new fields to course_stats if they don't exist (line 44: course_stat.get(k, 0)). However, this means that for legacy users with existing course_stats that don't have deleted_threads, deleted_responses, or deleted_replies fields, these will be initialized to 0 on the first update. This is correct, but consider whether a data migration is needed to ensure all existing course_stats have these fields set to 0 explicitly for consistency.

Copilot · 2026-01-13T06:43:20Z

forum/backends/mysql/api.py

+
+        # IMPORTANT: Restore replies (children) FIRST, then responses (parents)
+        # This prevents double-counting replies when both parent and children are restored
+
+        # First, restore all replies (comments with a parent)
+        replies = [c for c in deleted_comments if c.parent is not None]
+        for comment in replies:
+            if cls.restore_comment(str(comment.pk), restored_by=restored_by):
+                count += 1
+
+        # Then, restore all responses (comments without a parent)
+        responses = [c for c in deleted_comments if c.parent is None]
+        for comment in responses:
+            if cls.restore_comment(str(comment.pk), restored_by=restored_by):
+                count += 1
+
+        return count


The restore_user_deleted_comments method processes replies first, then responses. However, the comment states this prevents double-counting when both parent and children are restored. The logic here seems flawed: if a child reply is restored first (incrementing replies by 1), and then its parent response is restored, the parent restoration will count the child as "still deleted" (which it's not anymore after the first restore). This could lead to incorrect stats. Consider restoring parents first, or tracking which children have already been restored.

Copilot · 2026-01-13T06:43:20Z

forum/api/users.py

    backend = get_backend(course_id)()
    sort_criterion = backend.get_user_sort_criterion(sort_key)
-    exclude_from_stats = ["_id", "course_id"]
+    exclude_from_stats = ["_id", "course_id", "deleted_count"]


The exclude_from_stats list now includes "deleted_count" which means this computed field won't be returned in the user stats API. However, deleted_count is computed in the to_dict method (line 88-90 in models.py) and appears to be a useful stat. Consider whether this exclusion is intentional or if deleted_count should be exposed to API consumers.

Suggested change

exclude_from_stats = ["_id", "course_id", "deleted_count"]

exclude_from_stats = ["_id", "course_id"]

Copilot · 2026-01-13T06:43:21Z

forum/backends/mongodb/comments.py

+            # Hard delete: permanently remove
+            result = self._collection.delete_one({"_id": ObjectId(_id)})
+            result_count = result.deleted_count
+        if mode == "hard":


In the MongoDB delete method, there's duplicate logic checking mode == "hard" on line 302 and 289. The check on line 302 for updating parent child_count only happens in hard mode, but this logic block could be consolidated with the hard delete block above it (lines 299-301) to reduce code duplication and improve readability.

Suggested change

if mode == "hard":

Copilot · 2026-01-13T06:43:21Z

forum/backends/mongodb/api.py

+        # Add soft delete filtering
+        kwargs["is_deleted"] = {"$ne": True}
+        contents = list(Contents().get_list(**kwargs))
+
+        # Get all thread IDs mentioned in comments
+        comment_thread_ids = set()
+        for content in contents:
+            if content.get("_type") == "Comment" and content.get("comment_thread_id"):
+                comment_thread_ids.add(content["comment_thread_id"])
+


The get_contents method now adds "is_deleted": {"$ne": True} filtering to exclude soft deleted content. However, it also collects comment_thread_ids but doesn't use them (lines 1873-1876). This unused variable and logic should be removed or the filtering should be completed to also exclude comments whose threads are deleted.

Suggested change

# Add soft delete filtering

kwargs["is_deleted"] = {"$ne": True}

contents = list(Contents().get_list(**kwargs))

# Get all thread IDs mentioned in comments

comment_thread_ids = set()

for content in contents:

if content.get("_type") == "Comment" and content.get("comment_thread_id"):

comment_thread_ids.add(content["comment_thread_id"])

# Add soft delete filtering for contents themselves

kwargs["is_deleted"] = {"$ne": True}

contents = list(Contents().get_list(**kwargs))

# Exclude comments whose threads have been soft-deleted

comment_thread_ids: set[Any] = set()

for content in contents:

if content.get("_type") == "Comment" and content.get("comment_thread_id"):

comment_thread_ids.add(content["comment_thread_id"])

if comment_thread_ids:

deleted_threads = CommentThread().get_list(

_id={"$in": list(comment_thread_ids)},

is_deleted=True,

)

deleted_thread_ids = {thread["_id"] for thread in deleted_threads}

if deleted_thread_ids:

contents = [

content

for content in contents

if not (

content.get("_type") == "Comment"

and content.get("comment_thread_id") in deleted_thread_ids

)

]

Copilot · 2026-01-13T06:43:24Z

forum/backends/mongodb/api.py

    def get_thread(thread_id: str) -> dict[str, Any] | None:
        """Get thread from id."""
        thread = CommentThread().get(thread_id)


The get_thread method in MongoDB API no longer checks if thread is None before returning it. This means None will be returned for non-existent threads, which is correct, but the removed check was present for a reason. Verify that all callers of this method handle None correctly, especially since this is a behavior change.

Suggested change

def get_thread(thread_id: str) -> dict[str, Any] | None:

"""Get thread from id."""

thread = CommentThread().get(thread_id)

def get_thread(thread_id: str) -> dict[str, Any]:

"""Get thread from id."""

thread = CommentThread().get(thread_id)

if thread is None:

raise ObjectDoesNotExist(f"Thread with id {thread_id} does not exist")

Copilot · 2026-01-13T06:43:24Z

forum/backends/mongodb/comments.py

        )

        return result.modified_count



The delete method signature has changed but the type annotation shows 'type: ignore[override]'. This indicates the method signature doesn't match the parent class. Consider updating the parent class method signature in the abstract base to match, or document why the override is necessary.

Suggested change

# NOTE:

# The signature of this method intentionally differs from BaseContents.delete.

# Comments support both soft and hard deletion as well as cascading deletes of

# child comments, so we need extra parameters (mode, deleted_by) and a tuple

# return value (parent and child deletion counts). The abstract base cannot be

# broadened without impacting other backends, so we keep this override and

# explicitly ignore the type-checker override warning.

Copilot · 2026-01-13T06:43:25Z

forum/backends/mysql/api.py

+        # Count deleted content
+        deleted_threads = threads.filter(is_deleted=True).count()
+        deleted_responses = responses.filter(is_deleted=True).count()
+        deleted_replies = replies.filter(is_deleted=True).count()
+
        stats, _ = CourseStat.objects.get_or_create(user=author, course_id=course_id)
-        stats.threads = threads.count()
-        stats.responses = responses.count()
-        stats.replies = replies.count()
+        stats.threads = threads.count() - deleted_threads
+        stats.responses = responses.count() - deleted_responses
+        stats.replies = replies.count() - deleted_replies
+        stats.deleted_threads = deleted_threads
+        stats.deleted_responses = deleted_responses
+        stats.deleted_replies = deleted_replies


The build_course_stats method rebuilds stats by counting all content (including deleted) and then subtracting deleted counts. This approach is correct for rebuilding stats from scratch. However, the stats could become out of sync if content is directly modified in the database without going through the API layer. Consider adding database constraints or triggers to maintain consistency, or document that stats should be periodically rebuilt.

Copilot · 2026-01-13T06:43:25Z

forum/api/comments.py

+    # Update stats based on what was actually deleted
+    if responses_deleted > 0:
+        # A response (parent comment) was deleted
+        backend.update_stats_for_course(
+            author_id,
+            comment_course_id,
+            responses=-responses_deleted,
+            deleted_responses=responses_deleted,
+            replies=-replies_deleted,
+            deleted_replies=replies_deleted,
+        )
    else:
-        backend.update_stats_for_course(author_id, comment_course_id, responses=-1)
+        # Only a reply was deleted (no response)
+        backend.update_stats_for_course(
+            author_id,
+            comment_course_id,
+            replies=-replies_deleted,
+            deleted_replies=replies_deleted,
+        )


The delete_comment function updates stats for all comments regardless of whether they are anonymous. However, in the restore_comment and delete_thread functions, stats are only updated when content is not anonymous (checking anonymous or anonymous_to_peers flags). This inconsistency means that deleting anonymous content will incorrectly update stats, but restoring it won't restore those stats, leading to stat drift. The delete_comment function should check if the comment is anonymous before updating stats.

Copilot · 2026-01-13T06:43:25Z

forum/views/comments.py

            comment_id: The ID of the comment to be deleted.
        Body:
-            Empty.
+            deleted_by: Optional ID of the user performing the delete (defaults to authenticated user).


The documentation on line 145 states that deleted_by is an optional parameter in the request body, but there's no visible code change to extract this parameter from the request and pass it to the delete_comment function. This means the deleted_by tracking feature won't work through the API unless the view implementation is updated.

This was referenced Jan 12, 2026

feat: added soft delete functionality edx/frontend-app-discussions#14

Merged

feat: added soft delete functionality edx/edx-platform#83

Merged

feat: added soft delete functionality

c06b4e2

Alam-2U force-pushed the Cosmo2-793 branch from 0d3d40b to c06b4e2 Compare January 13, 2026 06:31

Alam-2U marked this pull request as ready for review January 13, 2026 06:35

Copilot AI review requested due to automatic review settings January 13, 2026 06:35

Copilot started reviewing on behalf of Alam-2U January 13, 2026 06:36 View session

Copilot AI reviewed Jan 13, 2026

View reviewed changes

Alam-2U requested a review from mraman-2U January 14, 2026 09:24

mraman-2U approved these changes Jan 14, 2026

View reviewed changes

Alam-2U merged commit 9d492b4 into master Jan 14, 2026
19 checks passed

Alam-2U deleted the Cosmo2-793 branch January 14, 2026 09:35

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feat: added soft delete functionality #10

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Alam-2U commented Jan 12, 2026 •

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	exclude_from_stats = ["_id", "course_id", "deleted_count"]
	exclude_from_stats = ["_id", "course_id"]

+    # NOTE:
+    # The signature of this method intentionally differs from BaseContents.delete.
+    # Comments support both soft and hard deletion as well as cascading deletes of
+    # child comments, so we need extra parameters (mode, deleted_by) and a tuple
+    # return value (parent and child deletion counts). The abstract base cannot be
+    # broadened without impacting other backends, so we keep this override and
+    # explicitly ignore the type-checker override warning.

feat: added soft delete functionality #10

feat: added soft delete functionality #10

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Alam-2U commented Jan 12, 2026 •

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