CODEWITHSUNDEEP
javascriptnode.jsuuid
Tomas
Tomas

Reputation: 1141

How to generate unique UUID every time function is called in nodeJs?

So I'm working on this project where I export some data files with sensitive information and I want to generate uuid for each of them. I'm using node uuid module but every time I run my function the UUID is actually the same and old file gets overwritten with a new file as its UUID is the same. Here's snipped of my code:

var nodeUuid = require('node-uuid');
var uuid = nodeUuid.v4();

function createFile(){
    var filename = 'reports-'+uuid+'.txt';
}
...
createFile();

So every time I call function createFile() I get the same UUID and my files are getting over-written, any idea how I could actually generate unique id for every new file?

Upvotes: 0

Views: 5290

Answers (3)

Nelson Owalo
Nelson Owalo

Reputation: 2414

I might be late to the party, but you can do this without a library: The script below is the minified version of node-uuid v4 only library

import { default as crypto } from 'crypto'

class _Uuid {
    static v4(offset = 0){
        let byteToHex = [], rnds = crypto.randomBytes(16)

            rnds[6] = (rnds[6] & 0x0f) | 0x40 // Per 4.4, set bits for version and `clock_seq_hi_and_reserved`
            rnds[8] = (rnds[8] & 0x3f) | 0x80 // Per 4.4, set bits for version and `clock_seq_hi_and_reserved`

        for (var i = 0; i < 256; ++i) { byteToHex[i] = (i + 0x100).toString(16).substr(1) }

        return ([byteToHex[rnds[offset++]], byteToHex[rnds[offset++]], byteToHex[rnds[offset++]], byteToHex[rnds[offset++]], '-', byteToHex[rnds[offset++]], byteToHex[rnds[offset++]], '-', byteToHex[rnds[offset++]], byteToHex[rnds[offset++]], '-', byteToHex[rnds[offset++]], byteToHex[rnds[offset++]], '-', byteToHex[rnds[offset++]], byteToHex[rnds[offset++]], byteToHex[rnds[offset++]], byteToHex[rnds[offset++]], byteToHex[rnds[offset++]], byteToHex[rnds[offset++]]]).join('')  
    }
}

const v4 = _Uuid.v4

export { v4 as default }

Usage

import { default as uuid } from '_Uuid'

uuid() // 3ceb4f8f-cef9-400f-a394-80da0334273b

This is an ES6 script that uses the bundled crypto library in node and facilitates simple, fast generation of RFC4122 compliant v4 UUIDS. Source Code

Upvotes: 0

Matt Harrison
Matt Harrison

Reputation: 13567

Currently you're only generating a single UUID when the script is first loaded. To generate a new one each time you call createFile(), simply move the generation inside your createFile() function:

var nodeUuid = require('node-uuid');

function createFile(){
    var uuid = nodeUuid.v4();
    var filename = 'reports-'+uuid+'.txt';
}

...
createFile();

Upvotes: 1

Andriy Kuba
Andriy Kuba

Reputation: 8263

Move v4() call in to the function 

function createFile(){
    var uuid = nodeUuid.v4();
    var filename = 'reports-'+uuid+'.txt';
}

Upvotes: 6

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