Create a nimiq cashlink using node.js

OfirApps · August 23, 2021, 8:58am

Hello, ive been searching for a lot of time and i havent found toturial/sample on how to make a cashlink using node.js
any suggestions?

NimiqSoeren · August 23, 2021, 9:54am

NimiqSoeren · August 23, 2021, 9:56am

The main magic happens in this function:

github.com

tomkha/nimiq-cashlinks/blob/a40c2a9cb60f74bef3000cd73b8375b5ee30d526/index.js#L34-L53


function createCashlink(privateKey, value, message = '', test = false) {
    const messageBytes = new Nimiq.SerialBuffer(Buffer.from(message, 'UTF-8'));


    const buffer = new Nimiq.SerialBuffer(
        Nimiq.PrivateKey.SIZE // key
        + 8 // value
        + (messageBytes.byteLength ? 1 : 0) // message length
        + messageBytes.byteLength // message
    );


    privateKey.serialize(buffer);
    buffer.writeUint64(value);
    if (messageBytes.byteLength) {
        buffer.writeUint8(messageBytes.byteLength);
        buffer.write(messageBytes);
    }


    const encoded = Nimiq.BufferUtils.toBase64Url(buffer).replace(/\./g, '=');
    return `https://hub.nimiq${test ? '-testnet' : ''}.com/cashlink/#${encoded}`;
}

OfirApps · August 23, 2021, 10:42am

thats great! but how do i fund the cashlink?
the code itself dosent explain… im making an api that will make a cashlinks and that dosent work

NimiqSoeren · August 24, 2021, 7:52am

To fund the cashlink, you need to send a transaction to the cashlink’s address.

You can follow the tutorials to learn how to create a Nimiq client and send a transaction:

The script linked above also does these steps:

github.com

tomkha/nimiq-cashlinks/blob/a40c2a9cb60f74bef3000cd73b8375b5ee30d526/index.js#L93-L95


const client = Nimiq.Client.Configuration.builder()
    .blockConfirmations(requiredConfirmations)
    .instantiateClient();

github.com

tomkha/nimiq-cashlinks/blob/a40c2a9cb60f74bef3000cd73b8375b5ee30d526/index.js#L104-L107


let wallet;
if (seed) {
    wallet = Nimiq.Wallet.loadPlain(seed);
    Nimiq.Log.i(TAG, `Wallet loaded from seed: ${wallet.address.toUserFriendlyAddress()}`);

github.com

tomkha/nimiq-cashlinks/blob/master/index.js#L148-L150


const validityStartHeight = await client.getHeadHeight();
const transactions = keyPairs.map(keyPair => wallet.createTransaction(keyPair.publicKey.toAddress(), value, fee, validityStartHeight));
const txDetails = await Promise.all(transactions.map(tx => client.sendTransaction(tx)));