From 3a93cbbed9c2f32936536f8ef0dc62e7947eb08e Mon Sep 17 00:00:00 2001
From: Muhammad Faraz  Maqsood <faraz.maqsood@a006-01130.home>
Date: Mon, 19 Aug 2024 23:53:21 +0500
Subject: [PATCH 1/7] feat: implement comment APIs - these call are
 implemented:     /comments/:comment_id DELETE (deletes parent/child comment) 
    /comments/:comment_id GET (get parent comment)     /comments/:comment_id
 POST (created child comment)     /comments/:comment_id PUT (updates
 parent/child comment)

---
 forum/models/comments.py          |  52 ++++++++--
 forum/serializers/comments_api.py |  77 +++++++++++++++
 forum/serializers/contents.py     |   2 +-
 forum/urls.py                     |  13 ++-
 forum/utils.py                    |   4 +
 forum/views/comments.py           | 152 ++++++++++++++++++++++++++++++
 6 files changed, 289 insertions(+), 11 deletions(-)
 create mode 100644 forum/serializers/comments_api.py
 create mode 100644 forum/views/comments.py

diff --git a/forum/models/comments.py b/forum/models/comments.py
index a804442c..957e9d68 100644
--- a/forum/models/comments.py
+++ b/forum/models/comments.py
@@ -7,6 +7,7 @@
 
 from bson import ObjectId
 
+from forum.models.users import Users
 from forum.models.contents import Contents
 
 
@@ -21,9 +22,10 @@ def insert(  # type: ignore  # pylint: disable=arguments-renamed
         self,
         body: str,
         course_id: str,
-        comment_thread_id: str,
+        parent_id: str,
         author_id: str,
-        author_username: str,
+        comment_thread_id: str = None,
+        author_username: str = None,
         anonymous: bool = False,
         anonymous_to_peers: bool = False,
         depth: int = 0,
@@ -44,13 +46,18 @@ def insert(  # type: ignore  # pylint: disable=arguments-renamed
         Returns:
             str: The ID of the inserted document.
         """
-        date = datetime.now()
+        date = datetime.now().strftime("%Y-%m-%dT%H:%M:%SZ")
+        comment = Contents().get(parent_id)
+        parent_child_count = comment.get("child_count")
+        if not comment_thread_id:
+            comment_thread_id = comment.get("comment_thread_id")
+
         comment_data = {
             "votes": self.get_votes_dict(up=[], down=[]),
             "visible": True,
             "abuse_flaggers": [],
             "historical_abuse_flaggers": [],
-            "parent_ids": [],
+            "parent_ids": [ObjectId(parent_id)] if parent_id else [],
             "at_position_list": [],
             "body": body,
             "course_id": course_id,
@@ -58,15 +65,20 @@ def insert(  # type: ignore  # pylint: disable=arguments-renamed
             "endorsed": False,
             "anonymous": anonymous,
             "anonymous_to_peers": anonymous_to_peers,
+            "parent_id": ObjectId(parent_id),
             "author_id": author_id,
             "comment_thread_id": ObjectId(comment_thread_id),
             "child_count": 0,
             "depth": depth,
-            "author_username": author_username,
+            "author_username": author_username or self.get_author_username(author_id),
             "created_at": date,
             "updated_at": date,
         }
         result = self._collection.insert_one(comment_data)
+        self._collection.update_one(
+            {"_id": ObjectId(parent_id)},
+            {"$set": {"child_count": parent_child_count + 1}},
+        )
         return str(result.inserted_id)
 
     def update(  # type: ignore
@@ -86,6 +98,12 @@ def update(  # type: ignore
         endorsed: Optional[bool] = None,
         child_count: Optional[int] = None,
         depth: Optional[int] = None,
+        closed: Optional[bool] = None,
+        edit_history: Optional[list[dict[str, Any]]] = [],
+        original_body: Optional[str] = None,
+        editing_user_id: Optional[str] = None,
+        edit_reason_code: Optional[str] = None,
+        endorsement_user_id: Optional[str] = None,
     ) -> int:
         """
         Updates a comment document in the database.
@@ -125,15 +143,35 @@ def update(  # type: ignore
             ("endorsed", endorsed),
             ("child_count", child_count),
             ("depth", depth),
+            ("closed", closed),
         ]
         update_data: Dict[str, Any] = {
             field: value for field, value in fields if value is not None
         }
+        if endorsed and endorsement_user_id:
+            update_data["endorsement"] = {
+                "user_id": endorsement_user_id,
+                "time": datetime.now().strftime("%Y-%m-%dT%H:%M:%SZ"),
+            }
 
-        date = datetime.now()
-        update_data["updated_at"] = date
+        if editing_user_id:
+            edit_history.append(
+                {
+                    "original_body": original_body,
+                    "reason_code": edit_reason_code,
+                    "editor_username": self.get_author_username(editing_user_id),
+                    "created_at": datetime.now().strftime("%Y-%m-%dT%H:%M:%SZ"),
+                }
+            )
+            update_data["edit_history"] = edit_history
+
+        update_data["updated_at"] = datetime.now().strftime("%Y-%m-%dT%H:%M:%SZ")
         result = self._collection.update_one(
             {"_id": ObjectId(comment_id)},
             {"$set": update_data},
         )
         return result.modified_count
+
+    def get_author_username(self, author_id):
+        user = Users().get(author_id)
+        return user.get("username")
diff --git a/forum/serializers/comments_api.py b/forum/serializers/comments_api.py
new file mode 100644
index 00000000..d1c1dea6
--- /dev/null
+++ b/forum/serializers/comments_api.py
@@ -0,0 +1,77 @@
+"""
+Serializer for the comment data.
+"""
+
+from rest_framework import serializers
+
+from forum.models.comments import Comment
+from forum.serializers.contents import EditHistorySerializer
+from forum.serializers.votes import VoteSummarySerializer
+
+
+class EndorsementSerializer(serializers.Serializer):
+    user_id = serializers.IntegerField()
+    time = serializers.DateTimeField(format="%Y-%m-%dT%H:%M:%SZ")
+
+
+class CommentsAPICommonSerializer(serializers.Serializer):
+    """
+    Serializer for handling user comment api calls.
+    """
+
+    id = serializers.CharField()
+    user_id = serializers.CharField()
+    thread_id = serializers.CharField()
+    username = serializers.CharField()
+    parent_id = serializers.CharField()
+    endorsed = serializers.BooleanField(default=False)
+    anonymous = serializers.BooleanField(default=False)
+    anonymous_to_peers = serializers.BooleanField(default=False)
+    closed = serializers.BooleanField(default=False)
+    body = serializers.CharField()
+    course_id = serializers.CharField()
+    parent_id = serializers.CharField(default=None, allow_null=True)
+    commentable_id = serializers.CharField(default="course")
+    created_at = serializers.DateTimeField(format="%Y-%m-%dT%H:%M:%SZ")
+    updated_at = serializers.DateTimeField(format="%Y-%m-%dT%H:%M:%SZ")
+    depth = serializers.IntegerField(default=0)
+    abuse_flaggers = serializers.ListField(
+        child=serializers.CharField(), allow_null=True
+    )
+    at_position_list = serializers.ListField(allow_null=True)
+    type = serializers.CharField()
+    child_count = serializers.IntegerField(default=0)
+    votes = VoteSummarySerializer()
+    edit_history = EditHistorySerializer(default=[], many=True)
+    sk = serializers.SerializerMethodField()
+    endorsement = EndorsementSerializer(default=None, required=False, allow_null=True)
+
+    def get_sk(self, obj):
+        is_child = True if obj.get("parent_id") else False
+        if is_child:
+            return "{parent_id}-{id}".format(
+                parent_id=obj.get("parent_id"), id=obj.get("_id")
+            )
+        else:
+            return "{id}".format(id=obj.get("_id"))
+
+
+class CommentsAPIGetSerializer(CommentsAPICommonSerializer):
+    """
+    Serializer for handling user comment get api calls.
+    """
+
+    def __init__(self, *args, **kwargs):
+        super().__init__(*args, **kwargs)
+        self.fields.pop("sk", None)
+
+
+class CommentsAPIPostAndDeleteSerializer(CommentsAPICommonSerializer):
+    """
+    Serializer for handling user comment post and delete api calls.
+    """
+
+    def __init__(self, *args, **kwargs):
+        super().__init__(*args, **kwargs)
+        self.fields.pop("sk", None)
+        self.fields.pop("endorsement", None)
diff --git a/forum/serializers/contents.py b/forum/serializers/contents.py
index 741b5ced..b893feab 100644
--- a/forum/serializers/contents.py
+++ b/forum/serializers/contents.py
@@ -21,7 +21,7 @@ class EditHistorySerializer(serializers.Serializer):  # type: ignore
     original_body = serializers.CharField()
     reason_code = serializers.CharField(allow_null=True, default=None)
     editor_username = serializers.CharField()
-    created_at = serializers.DateTimeField()
+    created_at = serializers.DateTimeField(format="%Y-%m-%dT%H:%M:%SZ")
 
     def create(self, validated_data: Dict[str, Any]) -> Any:
         """Raise NotImplementedError"""
diff --git a/forum/urls.py b/forum/urls.py
index 24721c35..fec31a3d 100644
--- a/forum/urls.py
+++ b/forum/urls.py
@@ -8,9 +8,10 @@
 from forum.views.pins import PinThreadAPIView, UnpinThreadAPIView
 from forum.views.proxy import ForumProxyAPIView
 from forum.views.votes import CommentVoteView, ThreadVoteView
+from forum.views.comments import CommentsAPIView
 
 api_patterns = [
-    # Thread APIs
+    # thread votes APIs
     path(
         "threads/<str:thread_id>/votes",
         ThreadVoteView.as_view(),
@@ -21,7 +22,7 @@
         CommentVoteView.as_view(),
         name="comment-vote",
     ),
-    # Comment APIs
+    # abuse comment/thread APIs
     path(
         "comments/<str:comment_id>/abuse_<str:action>",
         CommentFlagAPIView.as_view(),
@@ -32,13 +33,19 @@
         ThreadFlagAPIView.as_view(),
         name="thread-flags-api",
     ),
-    # Pin/Unpin thread APIs
+    # pin/unpin thread APIs
     path("threads/<str:thread_id>/pin", PinThreadAPIView.as_view(), name="pin-thread"),
     path(
         "threads/<str:thread_id>/unpin",
         UnpinThreadAPIView.as_view(),
         name="unpin-thread",
     ),
+    # comments APIs
+    path(
+        "comments/<str:comment_id>",
+        CommentsAPIView.as_view(),
+        name="comments-api",
+    ),
     # Proxy view for various API endpoints
     path(
         "<path:suffix>",
diff --git a/forum/utils.py b/forum/utils.py
index b4fa9359..2e4056f3 100644
--- a/forum/utils.py
+++ b/forum/utils.py
@@ -40,3 +40,7 @@ def handle_proxy_requests(request: HttpRequest, suffix: str, method: str) -> Res
         headers=request_headers,
         timeout=5.0,
     )
+
+
+def str_to_bool(value: str) -> bool:
+    return value.lower() in ("true", "1")
diff --git a/forum/views/comments.py b/forum/views/comments.py
new file mode 100644
index 00000000..e33d2d8b
--- /dev/null
+++ b/forum/views/comments.py
@@ -0,0 +1,152 @@
+"""Forum Comments API Views."""
+
+import logging
+from typing import Any
+
+from django.core.exceptions import ObjectDoesNotExist
+from rest_framework import status
+from rest_framework.permissions import AllowAny
+from rest_framework.request import Request
+from rest_framework.response import Response
+from rest_framework.serializers import ValidationError
+from rest_framework.views import APIView
+
+from forum.models import Comment
+from forum.serializers.comments_api import (
+    CommentsAPIGetSerializer,
+    CommentsAPIPostAndDeleteSerializer,
+)
+from forum.utils import str_to_bool
+
+log = logging.getLogger(__name__)
+
+
+class CommentsAPIView(APIView):
+    """
+    API View to handle GET, POST, PUT, and DELETE requests for comments.
+    """
+
+    permission_classes = (AllowAny,)
+
+    def get(self, request: Request, comment_id: str = None) -> Response:
+        """
+        Retrieves a parent comment.
+        For chile comments, below API is called that return all child comments in children field
+        url: http://localhost:8000/forum/api/v2/threads/66ab94950dead7001deb947a
+        """
+        try:
+            comment = Comment().get(comment_id)
+            if not comment:
+                raise ObjectDoesNotExist
+        except ObjectDoesNotExist:
+            return Response(
+                {"error": "Comment does not exist"}, status=status.HTTP_404_NOT_FOUND
+            )
+        data = self._prepare_response("get", comment)
+        return Response(data, status=status.HTTP_200_OK)
+
+    def post(self, request: Request, comment_id: str = None) -> Response:
+        """
+        Creates a new child comment.
+        For parent comment below API is called.
+        url: http://localhost:8000/forum/api/v2/threads/66ab94950dead7001deb947a/comments
+        """
+        data = request.data
+        # TODO validations
+        new_comment_id = Comment().insert(
+            body=data.get("body"),
+            course_id=data.get("course_id"),
+            anonymous=data.get("anonymous", False),
+            anonymous_to_peers=data.get("anonymous_to_peers", False),
+            author_id=data.get("user_id"),
+            parent_id=comment_id,
+            depth=1,
+        )
+        comment = Comment().get(new_comment_id)
+        data = self._prepare_response("post", comment)
+
+        return Response(data, status=status.HTTP_200_OK)
+
+    def put(self, request: Request, comment_id: str) -> Response:
+        """
+        Update an existing child and parent comment.
+        """
+        try:
+            comment = Comment().get(comment_id)
+            if not comment:
+                raise ObjectDoesNotExist
+        except ObjectDoesNotExist:
+            return Response(
+                {"error": "Comment does not exist"}, status=status.HTTP_404_NOT_FOUND
+            )
+
+        data = request.POST.dict()
+        update_comment_data: dict[str, Any] = {
+            "body": data.get("body", comment.get("body", "")),
+            "anonymous": str_to_bool(data.get("anonymous", False)),
+            "anonymous_to_peers": str_to_bool(data.get("anonymous_to_peers", False)),
+            "course_id": data.get("course_id", ""),
+            "closed": str_to_bool(data.get("closed", False)),
+            "author_id": data.get("user_id"),
+            "endorsed": str_to_bool(data.get("endorsed", False)),
+        }
+        if "editing_user_id" in data:
+            update_comment_data["editing_user_id"] = data.get("editing_user_id")
+
+        if "edit_reason_code" in data:
+            update_comment_data["edit_reason_code"] = data.get("edit_reason_code")
+
+        if "endorsement_user_id" in data:
+            update_comment_data["endorsement_user_id"] = data.get("endorsement_user_id")
+
+        update_comment_data["edit_history"] = comment.get("edit_history", [])
+        update_comment_data["original_body"] = comment.get("body")
+
+        Comment().update(comment_id, **update_comment_data)
+        updated_comment = Comment().get(comment_id)
+        data = self._prepare_response("put", updated_comment)
+
+        return Response(data, status=status.HTTP_200_OK)
+
+    def delete(self, request: Request, comment_id: str) -> Response:
+        """
+        Delete a comment.
+        """
+        try:
+            comment = Comment().get(comment_id)
+            if not comment:
+                raise ObjectDoesNotExist
+        except ObjectDoesNotExist:
+            return Response(
+                {"error": "Comment does not exist"}, status=status.HTTP_404_NOT_FOUND
+            )
+        data = self._prepare_response("delete", comment)
+        Comment().delete(comment_id)
+
+        return Response(data, status=status.HTTP_200_OK)
+
+    def _prepare_response(self, method, comment):
+        comment_data = {
+            **comment,
+            "id": str(comment.get("_id")),
+            "user_id": comment.get("author_id"),
+            "thread_id": str(comment.get("comment_thread_id")),
+            "username": comment.get("author_username"),
+            "parent_id": str(comment.get("parent_id")),
+            "type": comment.get("_type").lower(),
+        }
+        if method == "get":
+            serializer = CommentsAPIGetSerializer(data=comment_data)
+        elif method == "post":
+            serializer = CommentsAPIPostAndDeleteSerializer(data=comment_data)
+        elif method == "put":
+            if comment.get("parent_id"):
+                serializer = CommentsAPIPostAndDeleteSerializer(data=comment_data)
+            else:
+                serializer = CommentsAPIGetSerializer(data=comment_data)
+        else:
+            serializer = CommentsAPIPostAndDeleteSerializer(data=comment_data)
+        if not serializer.is_valid():
+            raise ValidationError(serializer.errors)
+
+        return serializer.data

From 774d25e75f37e09aae90a449c30d499b4c1cc37f Mon Sep 17 00:00:00 2001
From: Muhammad Faraz  Maqsood <faraz.maqsood@a006-01130.home>
Date: Tue, 20 Aug 2024 11:54:53 +0500
Subject: [PATCH 2/7] feat: handle edge cases and code refactoring - handle
 child_count of parent comment in case of child comment deletion - simplify
 code and use one serializer

---
 forum/models/comments.py          |  31 +++++--
 forum/serializers/comments_api.py |  30 ++-----
 forum/views/comments.py           | 144 +++++++++++++++++++-----------
 3 files changed, 125 insertions(+), 80 deletions(-)

diff --git a/forum/models/comments.py b/forum/models/comments.py
index c4943e67..8e645d36 100644
--- a/forum/models/comments.py
+++ b/forum/models/comments.py
@@ -45,10 +45,10 @@ def insert(
             str: The ID of the inserted document.
         """
         date = datetime.now().strftime("%Y-%m-%dT%H:%M:%SZ")
-        comment = BaseContents().get(parent_id)
-        parent_child_count = comment.get("child_count")
+        parent_comment = self.get(parent_id)
+        parent_child_count = parent_comment.get("child_count")
         if not comment_thread_id:
-            comment_thread_id = comment.get("comment_thread_id")
+            comment_thread_id = parent_comment.get("comment_thread_id")
 
         comment_data = {
             "votes": self.get_votes_dict(up=[], down=[]),
@@ -73,10 +73,7 @@ def insert(
             "updated_at": date,
         }
         result = self._collection.insert_one(comment_data)
-        self._collection.update_one(
-            {"_id": ObjectId(parent_id)},
-            {"$set": {"child_count": parent_child_count + 1}},
-        )
+        self.update(parent_id, child_count=parent_child_count + 1)
         return str(result.inserted_id)
 
     def update(
@@ -170,6 +167,26 @@ def update(
         )
         return result.modified_count
 
+    def delete(self, _id: str) -> int:
+        """
+        Deletes a comment from the database based on the id.
+
+        Args:
+            _id: The ID of the comment.
+
+        Returns:
+            The number of comments deleted.
+        """
+        comment = self.get(_id)
+        parent_comment_id = comment.get("parent_id")
+        parent_comment = parent_comment_id and self.get(parent_comment_id)
+        result = self._collection.delete_one({"_id": ObjectId(_id)})
+        if parent_comment:
+            self.update(
+                parent_comment_id, child_count=parent_comment.get("child_count") - 1
+            )
+        return result.deleted_count
+
     def get_author_username(self, author_id):
         user = Users().get(author_id)
         return user.get("username")
diff --git a/forum/serializers/comments_api.py b/forum/serializers/comments_api.py
index d1c1dea6..dbd08dd8 100644
--- a/forum/serializers/comments_api.py
+++ b/forum/serializers/comments_api.py
@@ -14,7 +14,7 @@ class EndorsementSerializer(serializers.Serializer):
     time = serializers.DateTimeField(format="%Y-%m-%dT%H:%M:%SZ")
 
 
-class CommentsAPICommonSerializer(serializers.Serializer):
+class CommentsAPISerializer(serializers.Serializer):
     """
     Serializer for handling user comment api calls.
     """
@@ -46,6 +46,13 @@ class CommentsAPICommonSerializer(serializers.Serializer):
     sk = serializers.SerializerMethodField()
     endorsement = EndorsementSerializer(default=None, required=False, allow_null=True)
 
+    def __init__(self, *args, **kwargs):
+        exclude_fields = kwargs.pop("exclude_fields", None)
+        super().__init__(*args, **kwargs)
+        if exclude_fields:
+            for field in exclude_fields:
+                self.fields.pop(field, None)
+
     def get_sk(self, obj):
         is_child = True if obj.get("parent_id") else False
         if is_child:
@@ -54,24 +61,3 @@ def get_sk(self, obj):
             )
         else:
             return "{id}".format(id=obj.get("_id"))
-
-
-class CommentsAPIGetSerializer(CommentsAPICommonSerializer):
-    """
-    Serializer for handling user comment get api calls.
-    """
-
-    def __init__(self, *args, **kwargs):
-        super().__init__(*args, **kwargs)
-        self.fields.pop("sk", None)
-
-
-class CommentsAPIPostAndDeleteSerializer(CommentsAPICommonSerializer):
-    """
-    Serializer for handling user comment post and delete api calls.
-    """
-
-    def __init__(self, *args, **kwargs):
-        super().__init__(*args, **kwargs)
-        self.fields.pop("sk", None)
-        self.fields.pop("endorsement", None)
diff --git a/forum/views/comments.py b/forum/views/comments.py
index e33d2d8b..416c2bb1 100644
--- a/forum/views/comments.py
+++ b/forum/views/comments.py
@@ -1,6 +1,5 @@
 """Forum Comments API Views."""
 
-import logging
 from typing import Any
 
 from django.core.exceptions import ObjectDoesNotExist
@@ -12,14 +11,9 @@
 from rest_framework.views import APIView
 
 from forum.models import Comment
-from forum.serializers.comments_api import (
-    CommentsAPIGetSerializer,
-    CommentsAPIPostAndDeleteSerializer,
-)
+from forum.serializers.comments_api import CommentsAPISerializer
 from forum.utils import str_to_bool
 
-log = logging.getLogger(__name__)
-
 
 class CommentsAPIView(APIView):
     """
@@ -28,21 +22,41 @@ class CommentsAPIView(APIView):
 
     permission_classes = (AllowAny,)
 
+    def _validate_comment(self, comment_id):
+        """
+        Validates the comment if it exists or not.
+
+        Parameters:
+            comment_id: The ID of the comment.
+        Response:
+            comment object for the given comment_id.
+        """
+        comment = Comment().get(comment_id)
+        if not comment:
+            raise ObjectDoesNotExist
+        return comment
+
     def get(self, request: Request, comment_id: str = None) -> Response:
         """
         Retrieves a parent comment.
         For chile comments, below API is called that return all child comments in children field
         url: http://localhost:8000/forum/api/v2/threads/66ab94950dead7001deb947a
+
+        Parameters:
+            request (Request): The incoming request.
+            comment_id: The ID of the comment.
+        Body:
+            Empty.
+        Response:
+            The details of the comment for the given comment_id.
         """
         try:
-            comment = Comment().get(comment_id)
-            if not comment:
-                raise ObjectDoesNotExist
+            comment = self._validate_comment(comment_id)
         except ObjectDoesNotExist:
             return Response(
                 {"error": "Comment does not exist"}, status=status.HTTP_404_NOT_FOUND
             )
-        data = self._prepare_response("get", comment)
+        data = self._prepare_response(comment, exclude_fields=["sk"])
         return Response(data, status=status.HTTP_200_OK)
 
     def post(self, request: Request, comment_id: str = None) -> Response:
@@ -50,6 +64,18 @@ def post(self, request: Request, comment_id: str = None) -> Response:
         Creates a new child comment.
         For parent comment below API is called.
         url: http://localhost:8000/forum/api/v2/threads/66ab94950dead7001deb947a/comments
+
+        Parameters:
+            request (Request): The incoming request.
+            comment_id: The ID of the parent comment for creating it's child comment.
+        Body:
+            body: The content of the comment.
+            course_id: The Id of the respective course.
+            user_id: The requesting user id.
+            anonymous: anonymous flag(True or False).
+            anonymous_to_peers: anonymous to peers flag(True or False).
+        Response:
+            The details of the comment that is created.
         """
         data = request.data
         # TODO validations
@@ -63,69 +89,93 @@ def post(self, request: Request, comment_id: str = None) -> Response:
             depth=1,
         )
         comment = Comment().get(new_comment_id)
-        data = self._prepare_response("post", comment)
+        data = self._prepare_response(comment, exclude_fields=["endorsement", "sk"])
 
         return Response(data, status=status.HTTP_200_OK)
 
     def put(self, request: Request, comment_id: str) -> Response:
         """
-        Update an existing child and parent comment.
+        Updates an existing child/parent comment.
+
+        Parameters:
+            request (Request): The incoming request.
+            comment_id: The ID of the comment to be edited.
+        Body:
+            fields to be updated.
+        Response:
+            The details of the comment that is updated.
         """
         try:
-            comment = Comment().get(comment_id)
-            if not comment:
-                raise ObjectDoesNotExist
+            comment = self._validate_comment(comment_id)
         except ObjectDoesNotExist:
             return Response(
                 {"error": "Comment does not exist"}, status=status.HTTP_404_NOT_FOUND
             )
 
         data = request.POST.dict()
+        fields = [
+            ("body", data.get("body")),
+            ("course_id", data.get("course_id")),
+            ("anonymous", str_to_bool(data.get("anonymous", False))),
+            ("anonymous_to_peers", str_to_bool(data.get("anonymous_to_peers", False))),
+            ("closed", str_to_bool(data.get("closed", False))),
+            ("endorsed", str_to_bool(data.get("endorsed", False))),
+            ("author_id", data.get("user_id")),
+            ("editing_user_id", data.get("editing_user_id")),
+            ("edit_reason_code", data.get("edit_reason_code")),
+            ("endorsement_user_id", data.get("endorsement_user_id")),
+        ]
         update_comment_data: dict[str, Any] = {
-            "body": data.get("body", comment.get("body", "")),
-            "anonymous": str_to_bool(data.get("anonymous", False)),
-            "anonymous_to_peers": str_to_bool(data.get("anonymous_to_peers", False)),
-            "course_id": data.get("course_id", ""),
-            "closed": str_to_bool(data.get("closed", False)),
-            "author_id": data.get("user_id"),
-            "endorsed": str_to_bool(data.get("endorsed", False)),
+            field: value for field, value in fields if value is not None
         }
-        if "editing_user_id" in data:
-            update_comment_data["editing_user_id"] = data.get("editing_user_id")
-
-        if "edit_reason_code" in data:
-            update_comment_data["edit_reason_code"] = data.get("edit_reason_code")
-
-        if "endorsement_user_id" in data:
-            update_comment_data["endorsement_user_id"] = data.get("endorsement_user_id")
-
         update_comment_data["edit_history"] = comment.get("edit_history", [])
         update_comment_data["original_body"] = comment.get("body")
 
         Comment().update(comment_id, **update_comment_data)
         updated_comment = Comment().get(comment_id)
-        data = self._prepare_response("put", updated_comment)
+        data = self._prepare_response(
+            updated_comment,
+            exclude_fields=(
+                ["endorsement", "sk"] if updated_comment.get("parent_id") else ["sk"]
+            ),
+        )
 
         return Response(data, status=status.HTTP_200_OK)
 
     def delete(self, request: Request, comment_id: str) -> Response:
         """
-        Delete a comment.
+        Deletes a comment.
+
+        Parameters:
+            request (Request): The incoming request.
+            comment_id: The ID of the comment to be deleted.
+        Body:
+            Empty.
+        Response:
+            The details of the comment that is deleted.
         """
         try:
-            comment = Comment().get(comment_id)
-            if not comment:
-                raise ObjectDoesNotExist
+            comment = self._validate_comment(comment_id)
         except ObjectDoesNotExist:
             return Response(
                 {"error": "Comment does not exist"}, status=status.HTTP_404_NOT_FOUND
             )
-        data = self._prepare_response("delete", comment)
+        data = self._prepare_response(comment, exclude_fields=["endorsement", "sk"])
         Comment().delete(comment_id)
 
         return Response(data, status=status.HTTP_200_OK)
 
-    def _prepare_response(self, method, comment):
+    def _prepare_response(self, comment, exclude_fields=[]):
+        """
+        Return serialized validated data.
+
+        Parameters:
+            comment: The comment details that needs to be serialized.
+            exclude_fields: Any fields that need to be excluded from response.
+
+        Response:
+            serialized validated data of the comment.
+        """
         comment_data = {
             **comment,
             "id": str(comment.get("_id")),
@@ -135,18 +185,10 @@ def _prepare_response(self, method, comment):
             "parent_id": str(comment.get("parent_id")),
             "type": comment.get("_type").lower(),
         }
-        if method == "get":
-            serializer = CommentsAPIGetSerializer(data=comment_data)
-        elif method == "post":
-            serializer = CommentsAPIPostAndDeleteSerializer(data=comment_data)
-        elif method == "put":
-            if comment.get("parent_id"):
-                serializer = CommentsAPIPostAndDeleteSerializer(data=comment_data)
-            else:
-                serializer = CommentsAPIGetSerializer(data=comment_data)
-        else:
-            serializer = CommentsAPIPostAndDeleteSerializer(data=comment_data)
+        serializer = CommentsAPISerializer(
+            data=comment_data, exclude_fields=exclude_fields
+        )
         if not serializer.is_valid():
             raise ValidationError(serializer.errors)
 
-        return serializer.data
+        return serializer.validated_data

From 05cbb6210746be9b3c4ac0eac58ae0904d7c9fae Mon Sep 17 00:00:00 2001
From: Muhammad Faraz  Maqsood <faraz.maqsood@a006-01130.home>
Date: Tue, 20 Aug 2024 13:25:55 +0500
Subject: [PATCH 3/7] fix: resolved quality checks - resolved quality checks -
 fixed Comments models insert method definition

---
 forum/models/comments.py          | 34 ++++++++++--------
 forum/serializers/comments_api.py | 42 +++++++++++++++++-----
 forum/utils.py                    |  1 +
 forum/views/comments.py           | 58 ++++++++++++++++++++-----------
 4 files changed, 91 insertions(+), 44 deletions(-)

diff --git a/forum/models/comments.py b/forum/models/comments.py
index 8e645d36..de0e96ea 100644
--- a/forum/models/comments.py
+++ b/forum/models/comments.py
@@ -20,10 +20,10 @@ def insert(
         self,
         body: str,
         course_id: str,
-        parent_id: str,
         author_id: str,
-        comment_thread_id: str = None,
-        author_username: str = None,
+        parent_id: Optional[str] = None,
+        comment_thread_id: Optional[str] = None,
+        author_username: Optional[str] = None,
         anonymous: bool = False,
         anonymous_to_peers: bool = False,
         depth: int = 0,
@@ -45,9 +45,9 @@ def insert(
             str: The ID of the inserted document.
         """
         date = datetime.now().strftime("%Y-%m-%dT%H:%M:%SZ")
-        parent_comment = self.get(parent_id)
-        parent_child_count = parent_comment.get("child_count")
-        if not comment_thread_id:
+        parent_comment = parent_id and self.get(parent_id)
+        parent_child_count = parent_comment and parent_comment.get("child_count")
+        if parent_comment and not comment_thread_id:
             comment_thread_id = parent_comment.get("comment_thread_id")
 
         comment_data = {
@@ -73,7 +73,8 @@ def insert(
             "updated_at": date,
         }
         result = self._collection.insert_one(comment_data)
-        self.update(parent_id, child_count=parent_child_count + 1)
+        if parent_id and parent_child_count:
+            self.update(parent_id, child_count=parent_child_count + 1)
         return str(result.inserted_id)
 
     def update(
@@ -94,7 +95,7 @@ def update(
         child_count: Optional[int] = None,
         depth: Optional[int] = None,
         closed: Optional[bool] = None,
-        edit_history: Optional[list[dict[str, Any]]] = [],
+        edit_history: Optional[list[dict[str, Any]]] = None,
         original_body: Optional[str] = None,
         editing_user_id: Optional[str] = None,
         edit_reason_code: Optional[str] = None,
@@ -150,6 +151,7 @@ def update(
             }
 
         if editing_user_id:
+            edit_history = [] if edit_history is None else edit_history
             edit_history.append(
                 {
                     "original_body": original_body,
@@ -178,15 +180,17 @@ def delete(self, _id: str) -> int:
             The number of comments deleted.
         """
         comment = self.get(_id)
-        parent_comment_id = comment.get("parent_id")
+        parent_comment_id = comment and comment.get("parent_id")
         parent_comment = parent_comment_id and self.get(parent_comment_id)
+        parent_comment_child_count = parent_comment and parent_comment.get(
+            "child_count"
+        )
         result = self._collection.delete_one({"_id": ObjectId(_id)})
-        if parent_comment:
-            self.update(
-                parent_comment_id, child_count=parent_comment.get("child_count") - 1
-            )
+        if parent_comment_id and parent_comment_child_count:
+            self.update(parent_comment_id, child_count=parent_comment_child_count - 1)
         return result.deleted_count
 
-    def get_author_username(self, author_id):
+    def get_author_username(self, author_id: str) -> str | None:
+        """Return username for the respective author_id(user_id)"""
         user = Users().get(author_id)
-        return user.get("username")
+        return user.get("username") if user else None
diff --git a/forum/serializers/comments_api.py b/forum/serializers/comments_api.py
index dbd08dd8..b34fc29e 100644
--- a/forum/serializers/comments_api.py
+++ b/forum/serializers/comments_api.py
@@ -2,19 +2,36 @@
 Serializer for the comment data.
 """
 
+from typing import Any
+
 from rest_framework import serializers
 
-from forum.models.comments import Comment
 from forum.serializers.contents import EditHistorySerializer
 from forum.serializers.votes import VoteSummarySerializer
 
 
-class EndorsementSerializer(serializers.Serializer):
-    user_id = serializers.IntegerField()
+class EndorsementSerializer(serializers.Serializer[dict[str, Any]]):
+    """
+    Serializer for handling endorsement of a comment
+
+    Attributes:
+        user_id (str): The endorsement user id.
+        time (datetime): The timestamp of when the user has endorsed the comment.
+    """
+
+    user_id = serializers.CharField()
     time = serializers.DateTimeField(format="%Y-%m-%dT%H:%M:%SZ")
 
+    def create(self, validated_data: dict[str, Any]) -> Any:
+        """Raise NotImplementedError"""
+        raise NotImplementedError
+
+    def update(self, instance: Any, validated_data: dict[str, Any]) -> Any:
+        """Raise NotImplementedError"""
+        raise NotImplementedError
+
 
-class CommentsAPISerializer(serializers.Serializer):
+class CommentsAPISerializer(serializers.Serializer[dict[str, Any]]):
     """
     Serializer for handling user comment api calls.
     """
@@ -46,18 +63,27 @@ class CommentsAPISerializer(serializers.Serializer):
     sk = serializers.SerializerMethodField()
     endorsement = EndorsementSerializer(default=None, required=False, allow_null=True)
 
-    def __init__(self, *args, **kwargs):
+    def __init__(self, *args: Any, **kwargs: Any) -> None:
         exclude_fields = kwargs.pop("exclude_fields", None)
         super().__init__(*args, **kwargs)
         if exclude_fields:
             for field in exclude_fields:
                 self.fields.pop(field, None)
 
-    def get_sk(self, obj):
-        is_child = True if obj.get("parent_id") else False
-        if is_child:
+    def get_sk(self, obj: dict[str, Any]) -> str:
+        """Return sk field"""
+        is_child = obj.get("parent_id")
+        if is_child is not None:
             return "{parent_id}-{id}".format(
                 parent_id=obj.get("parent_id"), id=obj.get("_id")
             )
         else:
             return "{id}".format(id=obj.get("_id"))
+
+    def create(self, validated_data: dict[str, Any]) -> Any:
+        """Raise NotImplementedError"""
+        raise NotImplementedError
+
+    def update(self, instance: Any, validated_data: dict[str, Any]) -> Any:
+        """Raise NotImplementedError"""
+        raise NotImplementedError
diff --git a/forum/utils.py b/forum/utils.py
index 2e4056f3..6c4782f9 100644
--- a/forum/utils.py
+++ b/forum/utils.py
@@ -43,4 +43,5 @@ def handle_proxy_requests(request: HttpRequest, suffix: str, method: str) -> Res
 
 
 def str_to_bool(value: str) -> bool:
+    """Convert str to bool."""
     return value.lower() in ("true", "1")
diff --git a/forum/views/comments.py b/forum/views/comments.py
index 416c2bb1..355ad6ce 100644
--- a/forum/views/comments.py
+++ b/forum/views/comments.py
@@ -1,6 +1,6 @@
 """Forum Comments API Views."""
 
-from typing import Any
+from typing import Any, Optional
 
 from django.core.exceptions import ObjectDoesNotExist
 from rest_framework import status
@@ -22,7 +22,7 @@ class CommentsAPIView(APIView):
 
     permission_classes = (AllowAny,)
 
-    def _validate_comment(self, comment_id):
+    def _validate_comment(self, comment_id: str) -> dict[str, Any]:
         """
         Validates the comment if it exists or not.
 
@@ -36,7 +36,7 @@ def _validate_comment(self, comment_id):
             raise ObjectDoesNotExist
         return comment
 
-    def get(self, request: Request, comment_id: str = None) -> Response:
+    def get(self, request: Request, comment_id: str) -> Response:
         """
         Retrieves a parent comment.
         For chile comments, below API is called that return all child comments in children field
@@ -59,7 +59,7 @@ def get(self, request: Request, comment_id: str = None) -> Response:
         data = self._prepare_response(comment, exclude_fields=["sk"])
         return Response(data, status=status.HTTP_200_OK)
 
-    def post(self, request: Request, comment_id: str = None) -> Response:
+    def post(self, request: Request, comment_id: str) -> Response:
         """
         Creates a new child comment.
         For parent comment below API is called.
@@ -80,16 +80,22 @@ def post(self, request: Request, comment_id: str = None) -> Response:
         data = request.data
         # TODO validations
         new_comment_id = Comment().insert(
-            body=data.get("body"),
-            course_id=data.get("course_id"),
+            body=data["body"],
+            course_id=data["course_id"],
             anonymous=data.get("anonymous", False),
             anonymous_to_peers=data.get("anonymous_to_peers", False),
-            author_id=data.get("user_id"),
+            author_id=data["user_id"],
             parent_id=comment_id,
             depth=1,
         )
         comment = Comment().get(new_comment_id)
-        data = self._prepare_response(comment, exclude_fields=["endorsement", "sk"])
+        try:
+            if comment:
+                data = self._prepare_response(
+                    comment, exclude_fields=["endorsement", "sk"]
+                )
+        except ValidationError as e:
+            return Response(e, status=status.HTTP_400_BAD_REQUEST)
 
         return Response(data, status=status.HTTP_200_OK)
 
@@ -116,10 +122,13 @@ def put(self, request: Request, comment_id: str) -> Response:
         fields = [
             ("body", data.get("body")),
             ("course_id", data.get("course_id")),
-            ("anonymous", str_to_bool(data.get("anonymous", False))),
-            ("anonymous_to_peers", str_to_bool(data.get("anonymous_to_peers", False))),
-            ("closed", str_to_bool(data.get("closed", False))),
-            ("endorsed", str_to_bool(data.get("endorsed", False))),
+            ("anonymous", str_to_bool(data.get("anonymous", "False"))),
+            (
+                "anonymous_to_peers",
+                str_to_bool(data.get("anonymous_to_peers", "False")),
+            ),
+            ("closed", str_to_bool(data.get("closed", "False"))),
+            ("endorsed", str_to_bool(data.get("endorsed", "False"))),
             ("author_id", data.get("user_id")),
             ("editing_user_id", data.get("editing_user_id")),
             ("edit_reason_code", data.get("edit_reason_code")),
@@ -133,13 +142,18 @@ def put(self, request: Request, comment_id: str) -> Response:
 
         Comment().update(comment_id, **update_comment_data)
         updated_comment = Comment().get(comment_id)
-        data = self._prepare_response(
-            updated_comment,
-            exclude_fields=(
-                ["endorsement", "sk"] if updated_comment.get("parent_id") else ["sk"]
-            ),
-        )
-
+        try:
+            if updated_comment:
+                data = self._prepare_response(
+                    updated_comment,
+                    exclude_fields=(
+                        ["endorsement", "sk"]
+                        if updated_comment.get("parent_id")
+                        else ["sk"]
+                    ),
+                )
+        except ValidationError as e:
+            return Response(e, status=status.HTTP_400_BAD_REQUEST)
         return Response(data, status=status.HTTP_200_OK)
 
     def delete(self, request: Request, comment_id: str) -> Response:
@@ -165,7 +179,9 @@ def delete(self, request: Request, comment_id: str) -> Response:
 
         return Response(data, status=status.HTTP_200_OK)
 
-    def _prepare_response(self, comment, exclude_fields=[]):
+    def _prepare_response(
+        self, comment: dict[str, Any], exclude_fields: Optional[list[str]] = None
+    ) -> dict[str, Any]:
         """
         Return serialized validated data.
 
@@ -183,7 +199,7 @@ def _prepare_response(self, comment, exclude_fields=[]):
             "thread_id": str(comment.get("comment_thread_id")),
             "username": comment.get("author_username"),
             "parent_id": str(comment.get("parent_id")),
-            "type": comment.get("_type").lower(),
+            "type": str(comment.get("_type", "")).lower(),
         }
         serializer = CommentsAPISerializer(
             data=comment_data, exclude_fields=exclude_fields

From 8a534a5c063a5a11c628dc776f3d5f3959c21145 Mon Sep 17 00:00:00 2001
From: Muhammad Faraz  Maqsood <faraz.maqsood@a006-01130.home>
Date: Tue, 20 Aug 2024 13:34:02 +0500
Subject: [PATCH 4/7] fix: previous tests for comments model

---
 tests/test_models/test_comments.py | 18 +++++++++++++++---
 1 file changed, 15 insertions(+), 3 deletions(-)

diff --git a/tests/test_models/test_comments.py b/tests/test_models/test_comments.py
index 48ba9b7d..aab39378 100644
--- a/tests/test_models/test_comments.py
+++ b/tests/test_models/test_comments.py
@@ -43,13 +43,25 @@ def test_list() -> None:
     author_username = "edly"
 
     Comment().insert(
-        "<p>Comment 1</p>", course_id, thread_id, author_id, author_username
+        "<p>Comment 1</p>",
+        course_id,
+        author_id,
+        comment_thread_id=thread_id,
+        author_username=author_username,
     )
     Comment().insert(
-        "<p>Comment 2</p>", course_id, thread_id, author_id, author_username
+        "<p>Comment 2</p>",
+        course_id,
+        author_id,
+        comment_thread_id=thread_id,
+        author_username=author_username,
     )
     Comment().insert(
-        "<p>Comment 3</p>", course_id, thread_id, author_id, author_username
+        "<p>Comment 3</p>",
+        course_id,
+        author_id,
+        comment_thread_id=thread_id,
+        author_username=author_username,
     )
 
     comments_list = Comment().list()

From 8490cc6c7692b4e7b059ff53367b9fd70ba94be1 Mon Sep 17 00:00:00 2001
From: Muhammad Faraz  Maqsood <faraz.maqsood@a006-01130.home>
Date: Tue, 20 Aug 2024 16:55:47 +0500
Subject: [PATCH 5/7] chore: remove comment

---
 forum/views/comments.py | 1 -
 1 file changed, 1 deletion(-)

diff --git a/forum/views/comments.py b/forum/views/comments.py
index 355ad6ce..42992f4f 100644
--- a/forum/views/comments.py
+++ b/forum/views/comments.py
@@ -78,7 +78,6 @@ def post(self, request: Request, comment_id: str) -> Response:
             The details of the comment that is created.
         """
         data = request.data
-        # TODO validations
         new_comment_id = Comment().insert(
             body=data["body"],
             course_id=data["course_id"],

From 4355c207662ebb44812df49e3927c1c83cb91f2d Mon Sep 17 00:00:00 2001
From: Muhammad Faraz  Maqsood <faraz.maqsood@a006-01130.home>
Date: Tue, 20 Aug 2024 17:13:08 +0500
Subject: [PATCH 6/7] fix: flags api tests as comments model is changed

---
 tests/test_views/test_flags.py | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/tests/test_views/test_flags.py b/tests/test_views/test_flags.py
index 7de3adbd..d7cd8913 100644
--- a/tests/test_views/test_flags.py
+++ b/tests/test_views/test_flags.py
@@ -56,9 +56,9 @@ def test_comment_flag_api(api_client: APIClient) -> None:
     comment_id = Comment().insert(
         "<p>Comment 1</p>",
         course_id,
-        comment_thread_id,
         author_id,
-        author_username,
+        comment_thread_id=comment_thread_id,
+        author_username=author_username,
         abuse_flaggers=[],
         historical_abuse_flaggers=[],
     )

From b42c710063d82177a6e897a70ddf13d2975eb6d2 Mon Sep 17 00:00:00 2001
From: Muhammad Faraz  Maqsood <faraz.maqsood@a006-01130.home>
Date: Tue, 20 Aug 2024 19:35:17 +0500
Subject: [PATCH 7/7] feat: use single serializer for comments - make changes
 to the previous comments serializers - resolved comments - fixed adding
 childs count if it was zero before

---
 forum/models/comments.py          | 20 +++----
 forum/serializers/comment.py      | 45 ++++++++++++++-
 forum/serializers/comments_api.py | 89 ------------------------------
 forum/serializers/contents.py     | 10 ++--
 forum/views/comments.py           | 92 ++++++++++++++++++++-----------
 5 files changed, 119 insertions(+), 137 deletions(-)
 delete mode 100644 forum/serializers/comments_api.py

diff --git a/forum/models/comments.py b/forum/models/comments.py
index 720957e8..fbb5f56c 100644
--- a/forum/models/comments.py
+++ b/forum/models/comments.py
@@ -55,19 +55,17 @@ def insert(
         Returns:
             str: The ID of the inserted document.
         """
-        date = datetime.now().strftime("%Y-%m-%dT%H:%M:%SZ")
         parent_comment = parent_id and self.get(parent_id)
-        parent_child_count = parent_comment and parent_comment.get("child_count")
+        parent_child_count = parent_comment and parent_comment.get("child_count") or 0
         if parent_comment and not comment_thread_id:
             comment_thread_id = parent_comment.get("comment_thread_id")
 
+        date = datetime.now()
         comment_data = {
             "votes": self.get_votes_dict(up=[], down=[]),
             "visible": visible,
-            "abuse_flaggers": [] if abuse_flaggers is None else abuse_flaggers,
-            "historical_abuse_flaggers": (
-                [] if historical_abuse_flaggers is None else historical_abuse_flaggers
-            ),
+            "abuse_flaggers": abuse_flaggers or [],
+            "historical_abuse_flaggers": historical_abuse_flaggers or [],
             "parent_ids": [ObjectId(parent_id)] if parent_id else [],
             "at_position_list": [],
             "body": body,
@@ -86,7 +84,7 @@ def insert(
             "updated_at": date,
         }
         result = self._collection.insert_one(comment_data)
-        if parent_id and parent_child_count:
+        if parent_id:
             self.update(parent_id, child_count=parent_child_count + 1)
         return str(result.inserted_id)
 
@@ -163,7 +161,7 @@ def update(
         if endorsed and endorsement_user_id:
             update_data["endorsement"] = {
                 "user_id": endorsement_user_id,
-                "time": datetime.now().strftime("%Y-%m-%dT%H:%M:%SZ"),
+                "time": datetime.now(),
             }
 
         if editing_user_id:
@@ -173,12 +171,12 @@ def update(
                     "original_body": original_body,
                     "reason_code": edit_reason_code,
                     "editor_username": self.get_author_username(editing_user_id),
-                    "created_at": datetime.now().strftime("%Y-%m-%dT%H:%M:%SZ"),
+                    "created_at": datetime.now(),
                 }
             )
             update_data["edit_history"] = edit_history
 
-        update_data["updated_at"] = datetime.now().strftime("%Y-%m-%dT%H:%M:%SZ")
+        update_data["updated_at"] = datetime.now()
         result = self._collection.update_one(
             {"_id": ObjectId(comment_id)},
             {"$set": update_data},
@@ -199,7 +197,7 @@ def delete(self, _id: str) -> int:
         parent_comment_id = comment and comment.get("parent_id")
         parent_comment = parent_comment_id and self.get(parent_comment_id)
         parent_comment_child_count = parent_comment and parent_comment.get(
-            "child_count"
+            "child_count",
         )
         result = self._collection.delete_one({"_id": ObjectId(_id)})
         if parent_comment_id and parent_comment_child_count:
diff --git a/forum/serializers/comment.py b/forum/serializers/comment.py
index 2e1558fb..697a0b6e 100644
--- a/forum/serializers/comment.py
+++ b/forum/serializers/comment.py
@@ -7,6 +7,28 @@
 from rest_framework import serializers
 
 from forum.serializers.contents import UserContentSerializer
+from forum.serializers.custom_datetime import CustomDateTimeField
+
+
+class EndorsementSerializer(serializers.Serializer[dict[str, Any]]):
+    """
+    Serializer for handling endorsement of a comment
+
+    Attributes:
+        user_id (str): The endorsement user id.
+        time (datetime): The timestamp of when the user has endorsed the comment.
+    """
+
+    user_id = serializers.CharField()
+    time = CustomDateTimeField()
+
+    def create(self, validated_data: dict[str, Any]) -> Any:
+        """Raise NotImplementedError"""
+        raise NotImplementedError
+
+    def update(self, instance: Any, validated_data: dict[str, Any]) -> Any:
+        """Raise NotImplementedError"""
+        raise NotImplementedError
 
 
 class UserCommentSerializer(UserContentSerializer):
@@ -21,13 +43,34 @@ class UserCommentSerializer(UserContentSerializer):
         thread_id (str): The ID of the thread the comment belongs to.
         parent_id (str or None): The ID of the parent comment, if any.
         child_count (int): The number of child comments nested under this comment.
+        sk (str or None): sk field, has ids data in it.
+        endorsement: saves endorsement data.
     """
 
     endorsed = serializers.BooleanField(default=False)
     depth = serializers.IntegerField(default=0)
     thread_id = serializers.CharField()
-    parent_id = serializers.CharField(default=None)
+    parent_id = serializers.CharField(default=None, allow_null=True)
     child_count = serializers.IntegerField(default=0)
+    sk = serializers.SerializerMethodField()
+    endorsement = EndorsementSerializer(default=None, required=False, allow_null=True)
+
+    def __init__(self, *args: Any, **kwargs: Any) -> None:
+        exclude_fields = kwargs.pop("exclude_fields", None)
+        super().__init__(*args, **kwargs)
+        if exclude_fields:
+            for field in exclude_fields:
+                self.fields.pop(field, None)
+
+    def get_sk(self, obj: dict[str, Any]) -> str:
+        """Return sk field"""
+        is_child = obj.get("parent_id")
+        if is_child is not None:
+            return "{parent_id}-{id}".format(
+                parent_id=obj.get("parent_id"), id=obj.get("_id")
+            )
+        else:
+            return "{id}".format(id=obj.get("_id"))
 
     def create(self, validated_data: Dict[str, Any]) -> Any:
         """Raise NotImplementedError"""
diff --git a/forum/serializers/comments_api.py b/forum/serializers/comments_api.py
deleted file mode 100644
index b34fc29e..00000000
--- a/forum/serializers/comments_api.py
+++ /dev/null
@@ -1,89 +0,0 @@
-"""
-Serializer for the comment data.
-"""
-
-from typing import Any
-
-from rest_framework import serializers
-
-from forum.serializers.contents import EditHistorySerializer
-from forum.serializers.votes import VoteSummarySerializer
-
-
-class EndorsementSerializer(serializers.Serializer[dict[str, Any]]):
-    """
-    Serializer for handling endorsement of a comment
-
-    Attributes:
-        user_id (str): The endorsement user id.
-        time (datetime): The timestamp of when the user has endorsed the comment.
-    """
-
-    user_id = serializers.CharField()
-    time = serializers.DateTimeField(format="%Y-%m-%dT%H:%M:%SZ")
-
-    def create(self, validated_data: dict[str, Any]) -> Any:
-        """Raise NotImplementedError"""
-        raise NotImplementedError
-
-    def update(self, instance: Any, validated_data: dict[str, Any]) -> Any:
-        """Raise NotImplementedError"""
-        raise NotImplementedError
-
-
-class CommentsAPISerializer(serializers.Serializer[dict[str, Any]]):
-    """
-    Serializer for handling user comment api calls.
-    """
-
-    id = serializers.CharField()
-    user_id = serializers.CharField()
-    thread_id = serializers.CharField()
-    username = serializers.CharField()
-    parent_id = serializers.CharField()
-    endorsed = serializers.BooleanField(default=False)
-    anonymous = serializers.BooleanField(default=False)
-    anonymous_to_peers = serializers.BooleanField(default=False)
-    closed = serializers.BooleanField(default=False)
-    body = serializers.CharField()
-    course_id = serializers.CharField()
-    parent_id = serializers.CharField(default=None, allow_null=True)
-    commentable_id = serializers.CharField(default="course")
-    created_at = serializers.DateTimeField(format="%Y-%m-%dT%H:%M:%SZ")
-    updated_at = serializers.DateTimeField(format="%Y-%m-%dT%H:%M:%SZ")
-    depth = serializers.IntegerField(default=0)
-    abuse_flaggers = serializers.ListField(
-        child=serializers.CharField(), allow_null=True
-    )
-    at_position_list = serializers.ListField(allow_null=True)
-    type = serializers.CharField()
-    child_count = serializers.IntegerField(default=0)
-    votes = VoteSummarySerializer()
-    edit_history = EditHistorySerializer(default=[], many=True)
-    sk = serializers.SerializerMethodField()
-    endorsement = EndorsementSerializer(default=None, required=False, allow_null=True)
-
-    def __init__(self, *args: Any, **kwargs: Any) -> None:
-        exclude_fields = kwargs.pop("exclude_fields", None)
-        super().__init__(*args, **kwargs)
-        if exclude_fields:
-            for field in exclude_fields:
-                self.fields.pop(field, None)
-
-    def get_sk(self, obj: dict[str, Any]) -> str:
-        """Return sk field"""
-        is_child = obj.get("parent_id")
-        if is_child is not None:
-            return "{parent_id}-{id}".format(
-                parent_id=obj.get("parent_id"), id=obj.get("_id")
-            )
-        else:
-            return "{id}".format(id=obj.get("_id"))
-
-    def create(self, validated_data: dict[str, Any]) -> Any:
-        """Raise NotImplementedError"""
-        raise NotImplementedError
-
-    def update(self, instance: Any, validated_data: dict[str, Any]) -> Any:
-        """Raise NotImplementedError"""
-        raise NotImplementedError
diff --git a/forum/serializers/contents.py b/forum/serializers/contents.py
index 0652243e..22ebf14d 100644
--- a/forum/serializers/contents.py
+++ b/forum/serializers/contents.py
@@ -126,14 +126,16 @@ class UserContentSerializer(serializers.Serializer[dict[str, Any]]):
     course_id = serializers.CharField()
     anonymous = serializers.BooleanField(default=False)
     anonymous_to_peers = serializers.BooleanField(default=False)
-    created_at = CustomDateTimeField()
-    updated_at = CustomDateTimeField()
-    at_position_list = serializers.ListField(default=[])
+    created_at = CustomDateTimeField(allow_null=True)
+    updated_at = CustomDateTimeField(allow_null=True)
+    at_position_list = serializers.ListField(allow_null=True)
     user_id = serializers.CharField(source="author_id")
     username = serializers.CharField(source="author_username")
     commentable_id = serializers.CharField(default="course")
     votes = VoteSummarySerializer()
-    abuse_flaggers = serializers.ListField(default=[])
+    abuse_flaggers = serializers.ListField(
+        child=serializers.CharField(), allow_null=True
+    )
     edit_history = EditHistorySerializer(default=[], many=True)
     closed = serializers.BooleanField(default=False)
     type = serializers.CharField()
diff --git a/forum/views/comments.py b/forum/views/comments.py
index 42992f4f..d470f575 100644
--- a/forum/views/comments.py
+++ b/forum/views/comments.py
@@ -11,7 +11,7 @@
 from rest_framework.views import APIView
 
 from forum.models import Comment
-from forum.serializers.comments_api import CommentsAPISerializer
+from forum.serializers.comment import UserCommentSerializer
 from forum.utils import str_to_bool
 
 
@@ -54,9 +54,13 @@ def get(self, request: Request, comment_id: str) -> Response:
             comment = self._validate_comment(comment_id)
         except ObjectDoesNotExist:
             return Response(
-                {"error": "Comment does not exist"}, status=status.HTTP_404_NOT_FOUND
+                {"error": "Comment does not exist"},
+                status=status.HTTP_404_NOT_FOUND,
             )
-        data = self._prepare_response(comment, exclude_fields=["sk"])
+        data = self._prepare_response(
+            comment,
+            exclude_fields=["sk"],
+        )
         return Response(data, status=status.HTTP_200_OK)
 
     def post(self, request: Request, comment_id: str) -> Response:
@@ -78,6 +82,14 @@ def post(self, request: Request, comment_id: str) -> Response:
             The details of the comment that is created.
         """
         data = request.data
+        fields_to_validate = ["body", "course_id", "user_id"]
+        for field in fields_to_validate:
+            if field not in data:
+                return Response(
+                    f"{field} is missing.",
+                    status=status.HTTP_400_BAD_REQUEST,
+                )
+
         new_comment_id = Comment().insert(
             body=data["body"],
             course_id=data["course_id"],
@@ -91,10 +103,14 @@ def post(self, request: Request, comment_id: str) -> Response:
         try:
             if comment:
                 data = self._prepare_response(
-                    comment, exclude_fields=["endorsement", "sk"]
+                    comment,
+                    exclude_fields=["endorsement", "sk"],
                 )
-        except ValidationError as e:
-            return Response(e, status=status.HTTP_400_BAD_REQUEST)
+        except ValidationError as error:
+            return Response(
+                error,
+                status=status.HTTP_400_BAD_REQUEST,
+            )
 
         return Response(data, status=status.HTTP_200_OK)
 
@@ -114,28 +130,12 @@ def put(self, request: Request, comment_id: str) -> Response:
             comment = self._validate_comment(comment_id)
         except ObjectDoesNotExist:
             return Response(
-                {"error": "Comment does not exist"}, status=status.HTTP_404_NOT_FOUND
+                {"error": "Comment does not exist"},
+                status=status.HTTP_404_NOT_FOUND,
             )
 
         data = request.POST.dict()
-        fields = [
-            ("body", data.get("body")),
-            ("course_id", data.get("course_id")),
-            ("anonymous", str_to_bool(data.get("anonymous", "False"))),
-            (
-                "anonymous_to_peers",
-                str_to_bool(data.get("anonymous_to_peers", "False")),
-            ),
-            ("closed", str_to_bool(data.get("closed", "False"))),
-            ("endorsed", str_to_bool(data.get("endorsed", "False"))),
-            ("author_id", data.get("user_id")),
-            ("editing_user_id", data.get("editing_user_id")),
-            ("edit_reason_code", data.get("edit_reason_code")),
-            ("endorsement_user_id", data.get("endorsement_user_id")),
-        ]
-        update_comment_data: dict[str, Any] = {
-            field: value for field, value in fields if value is not None
-        }
+        update_comment_data: dict[str, Any] = self._get_update_comment_data(data)
         update_comment_data["edit_history"] = comment.get("edit_history", [])
         update_comment_data["original_body"] = comment.get("body")
 
@@ -151,8 +151,11 @@ def put(self, request: Request, comment_id: str) -> Response:
                         else ["sk"]
                     ),
                 )
-        except ValidationError as e:
-            return Response(e, status=status.HTTP_400_BAD_REQUEST)
+        except ValidationError as error:
+            return Response(
+                error,
+                status=status.HTTP_400_BAD_REQUEST,
+            )
         return Response(data, status=status.HTTP_200_OK)
 
     def delete(self, request: Request, comment_id: str) -> Response:
@@ -171,9 +174,13 @@ def delete(self, request: Request, comment_id: str) -> Response:
             comment = self._validate_comment(comment_id)
         except ObjectDoesNotExist:
             return Response(
-                {"error": "Comment does not exist"}, status=status.HTTP_404_NOT_FOUND
+                {"error": "Comment does not exist"},
+                status=status.HTTP_404_NOT_FOUND,
             )
-        data = self._prepare_response(comment, exclude_fields=["endorsement", "sk"])
+        data = self._prepare_response(
+            comment,
+            exclude_fields=["endorsement", "sk"],
+        )
         Comment().delete(comment_id)
 
         return Response(data, status=status.HTTP_200_OK)
@@ -200,10 +207,31 @@ def _prepare_response(
             "parent_id": str(comment.get("parent_id")),
             "type": str(comment.get("_type", "")).lower(),
         }
-        serializer = CommentsAPISerializer(
-            data=comment_data, exclude_fields=exclude_fields
+        serializer = UserCommentSerializer(
+            data=comment_data,
+            exclude_fields=exclude_fields,
         )
         if not serializer.is_valid():
             raise ValidationError(serializer.errors)
 
-        return serializer.validated_data
+        return serializer.data
+
+    def _get_update_comment_data(self, data: dict[str, Any]) -> dict[str, Any]:
+        """convert request data to a dict excluding empty data"""
+
+        fields = [
+            ("body", data.get("body")),
+            ("course_id", data.get("course_id")),
+            ("anonymous", str_to_bool(data.get("anonymous", "False"))),
+            (
+                "anonymous_to_peers",
+                str_to_bool(data.get("anonymous_to_peers", "False")),
+            ),
+            ("closed", str_to_bool(data.get("closed", "False"))),
+            ("endorsed", str_to_bool(data.get("endorsed", "False"))),
+            ("author_id", data.get("user_id")),
+            ("editing_user_id", data.get("editing_user_id")),
+            ("edit_reason_code", data.get("edit_reason_code")),
+            ("endorsement_user_id", data.get("endorsement_user_id")),
+        ]
+        return {field: value for field, value in fields if value is not None}