In the previous example we demonstrated how you can instantiate a ScriptTransactionRequest to customize and build out a more complex transaction via a script. The same can be done using contracts, but this allows us to utilize functions available in the contract and access on-chain state. Allowing us to harness all of the power from an invocation scope and a transaction request.
This cookbook demonstrates how we can utilize a contract call to build out a custom transaction, allowing us to update on-chain state and transfer assets to a recipient address.
import { bn, buildFunctionResult, Contract, Provider, Wallet } from 'fuels';
import { LOCAL_NETWORK_URL, WALLET_PVT_KEY } from '../env';
import { CounterFactory } from '../typegend';
const provider = await Provider.create(LOCAL_NETWORK_URL);
const wallet = Wallet.fromPrivateKey(WALLET_PVT_KEY, provider);
const deploy = await CounterFactory.deploy(wallet);
const { contract } = await deploy.waitForResult();
const receiverWallet = Wallet.generate({ provider });
const amountToRecipient = bn(10_000); // 0x2710
// Connect to the contract
const contractInstance = new Contract(contract.id, contract.interface, wallet);
// Create an invocation scope for the contract function you'd like to call in the transaction
const scope = contractInstance.functions
.increment_count(amountToRecipient)
.addTransfer({
amount: amountToRecipient,
destination: receiverWallet.address,
assetId: provider.getBaseAssetId(),
});
// Build a transaction request from the invocation scope
const transactionRequest = await scope.getTransactionRequest();
// Add coin output for the recipient
transactionRequest.addCoinOutput(
receiverWallet.address,
amountToRecipient,
provider.getBaseAssetId()
);
const txCost = await wallet.getTransactionCost(transactionRequest);
transactionRequest.gasLimit = txCost.gasUsed;
transactionRequest.maxFee = txCost.maxFee;
await wallet.fund(transactionRequest, txCost);
// Submit the transaction
const response = await wallet.sendTransaction(transactionRequest);
await response.waitForResult();
// Get result of contract call
const { value } = await buildFunctionResult({
funcScope: scope,
isMultiCall: false,
program: contract,
transactionResponse: response,
});
console.log('value', value);
// <BN: 0x2710>