How to append arbitrary data to tx-extra?

[akildemir]

Hi, I have been trying to create a tx with arbitrary data in the NONCE field of tx-extra.

So far I tried getEtxra and setExtra functions(to get the already populated extra and append what I need and set it back) on the MoneroTxWallet type. But getEtxra returns undefined on a createTx result. And when just call setExtra then extra only becomes the extra I set, so tx becomes invalid.

Is there a way to do that using this lib? Here is little snippet of what I tried:

    // create the tx
    const tx = await this.wallet.createTx({
      address: to,
      amount: BigInt(amount_to_send),
      accountIndex: 0,
      relay: false,
    });

    // update tx-extra
    const NONCE_FIELD = Buffer.from([2]);
    const new_extra = Buffer.concat([tx.getExtra(), NONCE_FIELD, data]);
    tx.setExtra(new_extra);

    return this.wallet.relayTx(tx);

this returns Failed to commit tx error. Because when I print the tx I see there is an "extra" field now(that didn't exist before hence I was getting undefined) that is equal to data I set.

Thanks in advance.

[woodser]

As far as I can tell, monero-wallet-rpc does not support setting arbitrary extra data when creating transactions, and the libraries mirror the capabilities of monero-wallet-rpc.

I've opened an issue to set arbitrator data in monero-wallet-rpc, then the libraries can inherit that functionality: monero-project/monero#9731

[akildemir]

Oh got it. Thanks.