Solana: How combine presigned VersionedTransacctions in solana with js sdk

Combining Pre-Signed Transactions in Solana Using the JavaScript SDK

As a developer, you often need to handle transactions on the Solana blockchain. One of the most efficient ways to do this is by using the JavaScript SDK provided by Solana. In this article, we will explore how to combine pre-signed transactions into one.

What are Versioned Transactions?

Versioned transactions are an important part of the Solana transaction protocol. They allow multiple versions of a transaction to be stored on the blockchain, each with its own unique hash and timestamp. This is useful when you need to revert or undo certain changes made to a transaction.

Pre-Signed Transactions

A pre-signed transaction is a pre-signed version of a transaction that can be used to execute it without actually signing it. Pre-signing a transaction means generating an unsigned transaction that is signed with a public key, but does not include any actual data.

Merging pre-signed transactions

To combine pre-signed transactions into one, you can use the VersionedTransaction object and add all the versions together as a single transaction.

Here is an example of how to do this using the JavaScript SDK:

import { VersionedTransaction } from '@solana/web3.js';
export const combineVersionedTransactions = (
rawTransactions: VersionedTransaction[],
blockhash: string,
feePayer: PublicKey,
) => {
// Create a new transaction object
const tx = new VersionedTransaction();
// Add all the versions of the transactions to the new transaction
rawTransactions.forEach((version) => {
tx.add(version);
});
// Set the block hash, fee payer, and other properties as needed
// Return the combined pre-signed transaction
return tx;
};

Using the Combine Transaction Function

To use this function in your application, you can call it with the raw transactions, block hash, and fee payer:

const combineTransactions = combineVersionedTransactions(
[
new VersionedTransaction(),
new VersionedTransaction(), // Add another version of a transaction
],
'blockhash',
feePayer,
);

Benefits

Using this approach has several benefits:

• Reduced overhead: By not having to sign each individual transaction, you save computational resources and network bandwidth.

• Improved performance: Combining pre-signed transactions can improve the overall processing speed of your application.

• Simplified code: The VersionedTransaction object makes it easier to handle multiple versions of a transaction in a single transaction.

Example use case

Here is an example use case where we combine two versioned transactions:

import { combineVersionedTransactions } from './combineVersionedTransactions.js';
const feePayer = new PublicKey('feePayerAddress');
const blockhash = 'blockhash';
const transactions = [
new VersionedTransaction(),
new VersionedTransaction(), // Add another version of a transaction
];
const combinedTx = combineVersionedTransactions(
transactions,
blockhash,
feePayer,
);
console.log(combinedTx);

With this approach, you can easily combine pre-signed transactions into one and simplify your code. This makes it easier to manage multiple versions of a transaction on the Solana blockchain.