Building and Submitting TXs

This guide demonstrates how to build and submit transactions within an open Hydra Head using the cip30 interface and KuberHydraApiProvider.

Prerequisites

• Node.js environment
• libcardano and libcardano-wallet installed.
• An active Hydra Head (in "Open" state).
• A configured KuberHydraApiProvider instance.

Transaction builder

R efer to the KuberIDE TxBuilder Object Reference for details of all transaction builder properties.

This example demonstrates how to build and submit a simple transaction (sending Lovelace to an address) within an open Hydra Head using the KuberHydraApiProvider and a CIP-30 compatible wallet.

import { KuberHydraApiProvider } from "kuber-client"; // Adjust path as needed
import { Value,Ed25519Key ,loadCrypto } from "libcardano";
import {parseTransaction} from "libcardano/cardano/serialization";
import { ShelleyWallet, Cip30ShelleyWallet } from "libcardano-wallet";
import { readFileSync } from "fs";

async function runBuildAndSubmitTransactionExample() {
  // Initialize Hydra API Provider (replace with your Hydra node URL)
  const hydra = new KuberHydraApiProvider("http://172.31.6.1:8082");

  // Load test wallet signing key
  const testWalletSigningKey = await Ed25519Key.fromCardanoCliJson(
    JSON.parse(readFileSync(process.env.HOME + "/.cardano/preview/hydra-0/credentials/funds.sk", "utf-8")),
  );

  // Setup libcardano crypto and Shelley wallet
  await loadCrypto();
  const shelleyWallet = new ShelleyWallet(testWalletSigningKey);
  const cip30Wallet = new Cip30ShelleyWallet(hydra, hydra, shelleyWallet, 0);
  const walletAddress = (await cip30Wallet.getChangeAddress()).toBech32();

  console.log("Wallet Address:", walletAddress);

  // Ensure head is in 'Open' state
  const headState = await hydra.queryHeadState();
  if (headState.state !== "Open") {
    console.log("Head is not in 'Open' state. Please ensure it's in 'Open' state before running this example.");
    return;
  }
  console.log("Hydra Head is Open. Proceeding with transaction.");

  // Define the transaction outputs
  // For a comprehensive reference on transaction builder fields, refer to:
  // https://kuberide.com/kuber/docs/tx-builder-reference
  const txBuilder = {
    outputs: [{ address: walletAddress, value: "3_000_000" }], // Sending 3 ADA
    changeAddress: walletAddress,
  };

  try {
    // Use the buildAndSubmitWithWallet function from KuberProvider
    const submitResult = await hydra.buildAndSubmitWithWallet(cip30Wallet, txBuilder);
    const parsedTx = parseTransaction(submitResult.updatedTx)
    console.log("Transaction submitted to Hydra Head. Hash:",parsedTx.hash);
    console.log("CBOR Hex:", submitResult.updatedTxBytes.toString('hex'));

  } catch (error: unknown) {
    if (error instanceof Error) {
      console.error("Error building or submitting transaction:", error.message);
    } else {
      console.error("An unknown error occurred:", error);
    }
  }
}

runBuildAndSubmitTransactionExample();