How to use findByIdAndUpdate on mongodb? - node.js

Question

I am a noobie in coding and I am having an issue with how to use properly MongoDB. I have a parent object classroom containing an array of objects - comments. I am trying to update the content of 1 selected comment.
originally I updated the state of the whole "classroom" in the react and passed all the data and $set {req.body} in findByIdAndUpdate.
I want to achieve the same result if I only pass to my axios request classId, commentId and comment data and not whole classroom / all comments
I tried to filter selected comment out of the array of comments and concat updated comment, but that did not work. Clearly, I have any idea what is going on and docs don't make it any easier for me to understand.
my classroom schema:
var ClassroomSchema = new Schema({
title: String,
teacher: String,
info: String,
image_url: String,
comments: [Comment.schema]
});
comment schema:
var CommentSchema = new Schema()
CommentSchema.add({
content: String,
comments: [CommentSchema],
created_at: {
type: Date,
default: Date.now
}
});
original solution:
function update(req, res){
Comment.findById(req.params.comment_id, function(err, comment) {
if(err) res.send(err)
comment.content = req.body.content;
comment.save();
console.log(req.body.comments)
Classroom.findByIdAndUpdate(req.params.classroom_id,
{$set: req.body}, function(err, classroom){
if (err) {
console.log(err);
res.send(err);
} else {
commentToUpdate = req.body.commentData;
res.json(classroom);
}
});
});
}
my current failing atempt:
function update(req, res){
console.log('update => req.body: ', req.body);
console.log('req.params', req.params)
Comment.findById(req.params.comment_id, function(err, comment) {
if(err) res.send(err)
comment.content = req.body.content;
comment.save();
console.log('comment: ', comment);
Classroom.findById(req.params.classroom_id, function(err, classroom) {
console.log('CLASSROOM findByIdAndUpdate classroom: ', classroom)
// console.log('reg.body: ', req.body)
if (err) {
console.warn('Error updating comment', err);
res.send(err);
} else {
// commentToUpdate = req.body.commentData;
old_comments = classroom.comments;
console.log('comments: ', old_comments);
Classroom.findByIdAndUpdate(req.params.classroom_id,
{$set:
{ comments: old_comments.filter(comt._id !== comment._id).concat(comment)}
}, function(err, updatedClassroom) {
if (err) {
console.warn(err);
} else {
res.json(updatedClassroom);
}
});
}
});
});
}

Answer 1

haven't tested, but try this.
function update(req, res) {
Classroom.update(
{ _id: req.params.classroom_id, "comments._id": req.params.comment_id },
{ $set: { "comments.$.content": req.body.content } },
function(err) {
..
}
);
}