mongoose query within while loop not working

Question

I create my own primary key for mongodb collections in my node js app. In order to make sure generated key is unique I have to check if a collection by that generated key does not exist already. This is the code but its not working due to synchronous call:

let id = makeid()
let unique = false
$this = this
while(!unique) {

    try {
    property.findById(id, 'proptype', function (error, property) {
        if (error) { 
             console.log('not found, generated key is unique')
            $this.unique = true
        } else {
            $this.unique = false
            $this.id = makeid()
        }
      })
    } catch(e) 
    {
        console.log('exception: ' + e)
    }
}

How to fix this issue? I am looking for answer with working code. What happens is that it becomes infinite loop and each loop executes the query repeatedly.

Rahul Sharma · Accepted Answer · 2018-03-29 08:53:53Z

1

try this

const uniqueCheck = async () => {
    let id = makeid();
    let unique = false
    $this = this
    while (!unique) {
        try {
            const property = await (property.findById(id, 'proptype').exec());
            if (property) {
                $this.unique = false;
                $this.id = makeid();
            } else {
                $this.unique = true
            }
        } catch (e) {
            console.log('exception: ' + e);
            $this.unique = true
        }
    }
}

answered Mar 29, 2018 at 8:53

Rahul Sharma

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Comments

NikNik · Accepted Answer · 2018-03-29 09:43:04Z

0

You should use objectId:

var ObjectID = require('mongodb').ObjectID;

and to generate use: new ObjectID()

The collision probability will be very very low: document

answered Mar 29, 2018 at 9:43

NikNik

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