Mongoose add an object to nested array of objects in the database using push method

Question

in this function i find the post by post id then find a specific comment within this post by comment id, then i check if the nested array of objects likes contains user id, if no then i push user id to likes array, otherwise i remove it, but it doesn't work as it doesn't add the user id to likes array, what's wrong?

const likeComment = async (req, res) => {
  try {
    const post = await Post.findById(req.body.postId);
    const comment = post.comments.find(
      (comment) => comment.id === req.body.commentId
    );
    if (comment.likes.includes(req.body.userId)) {
      var index = comment.likes.indexOf(req.body.userId);
      if (index !== -1) {
        comment.likes.splice(index, 1);
      }
      res.status(200).json("you disliked this comment");
    } else {
      comment.likes.push(req.body.userId);
      res.status(200).json("you liked this comment");
    }
  } catch (err) {
    console.log(err);
    res.status(500).json(err);
  }
};

Answer 1

the answer is i need to do post.save();