wait findOneAndUpdate in a loop end

Question

names.forEach((o, i) => {
                Name.findOneAndUpdate({name: o.name}, o, {upsert: true, 'new': true})
                .then(result => {
                    res.json(result);
                })
            })

I cant do res.json in above's loop, how to do handle this case? I want to find name exist or not, if exist don't do anything, otherwise insert the names.

You can use [async.map()](https://caolan.github.io/async/docs.html#map) but ensure you execute `findOneAndUpdate` using a callback instead of returning a Promise. — Mikey, Nov 11 '17 at 13:53

Mykola Borysyuk · Accepted Answer · 2017-11-11T14:21:06.640

3

First of all read this.

What is the difference between synchronous and asynchronous programming (in node.js)

You mixing it up.

To fix your code you can use promises...

For example

function runUpdate(obj) {
   return new Promise((resolve, reject) => {
     //you update code here

    Name.findOneAndUpdate({name: obj.name}, {$setOnInsert: obj}, { upsert: true })
      .then(result => resolve())
      .catch(err => reject(err))
    });
  });
}

Now you can run loop and use promise all

let promiseArr = [];
names.forEach(obj => promiseArr.push(runUpdate(obj)));

Finally

Promise.all(promiseArr)
.then((res) => //res.json here)
.catch(err => //err res here)

About not updating documents on existanse. Check this out. https://docs.mongodb.com/manual/reference/operator/update/setOnInsert/#op._S_setOnInsert

Hope this helps.

edited Nov 11 '17 at 14:21

answered Nov 11 '17 at 14:01

Mykola Borysyuk

3,373
1
18
24

upsert true is needed because if the name is not exist, create a new name. – Jenny Mok Nov 11 '17 at 14:13
Oh sorry my mistake..Give me a second – Mykola Borysyuk Nov 11 '17 at 14:17
yes, if exist don't insert. It's like you do scraping for a list and then put into db, you don't want to even update it if it exist, if it don't insert a new document. – Jenny Mok Nov 11 '17 at 14:17
I tried your code, `setOnInsert` is needed? I simply state `obj` and it just worked. – Jenny Mok Nov 11 '17 at 14:23
1

Well. I think so. Because with upsert true if document were found it will run $set if not it will run insert with $set and $setOnInsert from docs. So to make sure that you only do stuff on isert you need this operator. – Mykola Borysyuk Nov 11 '17 at 14:24
No problem. Glad it helps. – Mykola Borysyuk Nov 11 '17 at 14:27

Maicon Gilton · Answer 2 · 2020-11-07T23:10:35.437

0

This works for me

const promises = names.map(async obj => 
   await Name.findOneAndUpdate(
      {name: obj.name}, 
      obj, 
      {upsert: true, 'new': true}
   )
)
await Promise.all(promises)

console.log('test')

if you run this code you will see 'test' only appears after the promises.

edited Nov 07 '20 at 23:10

answered Nov 07 '20 at 22:44

Maicon Gilton

581
1
7
6

wait findOneAndUpdate in a loop end

2 Answers2