Custom Transactions

There may be scenarios where you need to build out transactions that involve multiple program types and assets; this can be done by instantiating a ScriptTransactionRequest. This class allows you to a append multiple program types and assets to a single transaction.

Consider the following script that transfers multiple assets to a contract:

script;

use std::asset::force_transfer_to_contract;

fn main(
    contract_address: b256,
    asset_a: AssetId,
    amount_asset_a: u64,
    asset_b: AssetId,
    amount_asset_b: u64,
) -> bool {
    let wrapped_contract = ContractId::from(contract_address);

    force_transfer_to_contract(wrapped_contract, asset_a, amount_asset_a);
    force_transfer_to_contract(wrapped_contract, asset_b, amount_asset_b);
    true
}

See code in context

---

This script can be executed by creating a ScriptTransactionRequest, appending the resource and contract inputs/outputs and then sending the transaction, as follows:

import { BN, ScriptTransactionRequest } from 'fuels';
import type { CoinQuantityLike } from 'fuels';

// 1. Create a script transaction using the script binary
const { minGasPrice } = contract.provider.getGasConfig();

const request = new ScriptTransactionRequest({
  ...defaultTxParams,
  gasLimit: 3_000_000,
  script: scriptBin,
  gasPrice: minGasPrice,
});

// 2. Instantiate the script main arguments
const scriptArguments = [
  contract.id.toB256(),
  { value: ASSET_A },
  new BN(1000),
  { value: ASSET_B },
  new BN(500),
];

// 3. Populate the script data and add the contract input and output
request.setData(abiContents, scriptArguments).addContractInputAndOutput(contract.id);

// 4. Calculate the transaction fee
const { maxFee } = await provider.getTransactionCost(request);

// 5. Get the transaction resources
const quantities: CoinQuantityLike[] = [
  [1000, ASSET_A],
  [500, ASSET_B],
  [maxFee, BaseAssetId],
];

const resources = await wallet.getResourcesToSpend(quantities);

request.addResources(resources);

// 6. Send the transaction
const tx = await wallet.sendTransaction(request);
await tx.waitForResult();

See code in context