Mongodb find specific comment within array of objects in post collection - node.js

Question

i store comments in post collection like this:
...
const postSchema = new mongoose.Schema(
{
body: {
type: String,
},
userId: {
type: String,
required: true,
},
likes: {
type: Array,
default: [],
},
img: {
type: String,
default: null,
},
comments: [
{
body: {
type: String,
required: true,
},
userId: {
type: String,
required: true,
},
postId: {
type: String,
required: true,
},
},
{ timestamps: true },
],
},
{ timestamps: true }
);
...
i created this put route to update comment:
app.put("/update-comment", (req, res) => {
posts.updateComment(req, res);
});
updateComment function:
const updateComment = async (req, res) => {
try {
const post = await Post.findById(req.body.postId);
const comment = await post.comments.map((commentObj) => {
return commentObj.find({ _id: req.body.commentId });
});
await comment.updateOne({ $set: req.body });
res.status(200).json(comment);
} catch (err) {
res.status(500).json(err);
}
};
it finds the post by postId and simply loop the comments array to find the comment object with the comment id provided, i tried this route with postman providing the following json body:
{
"postId":"6242a4c75bce78154824fc8f",
"commentId":"6242ac32a61fd275ed13846b",
"body":"my first comment updated"
}
but it doesn't work, it returns 500 internal error, if i replaced the code with this:
try {
const post = await Post.findById(req.body.postId);
const comment = post.comments;
res.status(200).json(comment);
} catch (err) {
res.status(500).json(err);
}
it will indeed return the comments within that post as an array of objects, i don't know what's wrong, i made sure the postId and commentId provided by the json body is correct, what's the problem?