Node js, Wait, until get all data from MongoDB - node.js

Question

I have a problem with async function and callbacks in Node js. I need to get my friends' all posts and display it. But if i do that without setTimeout(), it returns only some part of data. How can i solve this problem without putting setTimeout? Of course it's absurd to wait for 5-6 or 10 seconds to get all data. I also tried with Promises, but again response is incomplete. Please someone can help me?
//Sending request with axios to Controller
axios.post(packages.proxy+'users/getFriendsPosts',{id: user_id},config)
.then(res => {
// Code for displaying result
})
//User Controller
router.post("/getFriendsPosts", getFriendsPosts);
//Send request body to userService.js
function getFriendsPosts(req, res, next) {
userService.getFriendsPosts(req.body, function(posts, user){
res.json({posts,user});
})
.catch(err => next(err));
}
//userService.js
module.exports = {
getFriendsPosts,
};
async function getFriendsPosts(user,callback){
var arr = [];
var array = [];
MongoClient.connect(url, async function(errr, db) {
if (errr) throw errr;
var dbo = db.db("drone-x");
//Find user
dbo.collection("users").find({_id: ObjectId(user.id)}).toArray(async function(err, result) {
if (err) throw err;
result.forEach(async function(element, index) {
if(element.friends.length != 0){
element.friends.forEach(async function(elem) {
//Find user's friends
dbo.collection("users").find({_id: ObjectId(elem.id)}).toArray(async function(error, res) {
if (error) throw error;
//push user's friends to arr
arr.push(res);
res.forEach(async function(elements) {
//Find user's friends posts
dbo.collection("posts").find({userId: elements._id.toString()}).toArray(async function(errors, results) {
if (errors) throw errors;
//push user's friends posts to array
array.push(results);
//callback results through setTimeout
setTimeout(async function(){ await callback(array, arr); db.close(); }, 2000);
});
});
});
});
}
else
{
await callback("0");
}
});
});
});
}
If i don't use setTimeout function, it just returns 2-3 data, but with setTimeout, it returns all data. And if data will be raise, then i need to increase the setTimeout time. But of course it's not good idea. Someone can help me?

Answer 1

You should use try catch in this code
getFriendsPosts = async (user,callback) => {
const arr = [];
const array = [];
const db = await MongoClient.connect(url);
const dbo = db.db("drone-x");
const results = await dbo.collection("users").find({_id: ObjectId(user.id)})
const resultPromise = _.map(results, async element => {
const friends = _.get(element, 'friends', [])
if(friends.length != 0) {
const friendPromise = _.map(friends, async friend => {
const ress = await dbo.collection("users").find({_id: ObjectId(friend.id)})
arr.push(ress);
const resPromise = _.map(ress, async res => {
const posts = await dbo.collection("posts").find({userId: res._id.toString()})
const postPromise = _.map(posts, post => {
array.push(post);
})
await Promise.all(postPromise)
})
await Promise.all(resPromise)
})
await Promise.all(friendPromise)
}
})
await Promise.all(resultPromise)
return { arr , array }
}
I am not recommand this way it take too much time. You should use mongoose and use aggregation for long Query.