Find if User Exist in array mongodb and Nodejs - node.js

Question

I have this opportunity model that has this field likes, which is an array of users. How do I check first if the user exist already in that array and if they do I pull them and if they don't I push them back I am building a like creteria for posts
Here is my opportunity model
const mongoose = require("mongoose");
const OpportunityModel = new mongoose.Schema({
user: {
type: mongoose.Schema.Types.ObjectId,
ref: "User",
},
content: {
type: String,
required: true,
trim: true,
},
likes: [
{
type: mongoose.Schema.Types.ObjectId,
ref: "User",
},
],
image: [
{
type: Object,
},
],
share_with_thoughts: {
type: mongoose.Schema.Types.ObjectId,
ref: "Shares",
},
comments: {
type: mongoose.Schema.Types.ObjectId,
ref: "Comment",
},
is_opportunity_applied: [
{
type: mongoose.Schema.Types.ObjectId,
ref: "User",
},
],
});
const Opportunity = mongoose.model("Opportunity", OpportunityModel);
module.exports = Opportunity;
What I tried doing but did not work
const likeOrUnlikeOpportunity = expressAsyncHandler(async (req, res) => {
let userId = req.user._id;
let opportunityId = req.params.opportunityId;
let isUserExist = await Opportunity.find({
$and: [{ _id: opportunityId }, { likes: { $elemMatch: { $eq: userId } } }],
}).populate("user", "user_id user_name");
if (isUserExist.length > 0) {
const unliked = await Opportunity.findByIdAndUpdate(
opportunityId,
{
$pull: { users: userId },
},
{ new: true }
).populate("user", "user_id user_name");
if (!unliked) {
res.status(500).send({ ErrMessaage: "an error occured" });
} else {
res.status(200).json(unliked);
}
} else {
const added = await Opportunity.findByIdAndUpdate(
opportunityId,
{
$push: { users: userId },
},
{ new: true }
).populate("user", "user_id user_name");
if (!added) {
res.status(500).send({ ErrMessaage: "an error occured" });
} else {
res.status(200).json(added);
}
}
});

Answer 1

In this case, the action should be dynamic [like | unlike] function, You don't have to chain the function since the like and unlike function/api can't be called at the same time.
Make Your Query Conditional;
Just make sure you have a way to identify between like and unlike.
const {like, postId} = req.body;
let query = {[`${'$' + (like ? 'push' : 'pull')}`]: {likes: userId}};
//assumes that you have the post id
// you can decide not to wait for it to update, just to be sure it did update
await post.findByIdAndUpdate(postId, query).exec()
I hope this helps.