Custom Transactions From Contract Calls

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 { Contract, bn, buildFunctionResult } from 'fuels';

const amountToRecipient = bn(10_000); // 0x2710
// Connect to the contract
const contractInstance = new Contract(contract.id, contract.interface, senderWallet);
// Create an invocation scope for the contract function you'd like to call in the transaction
const scope = contractInstance.functions.increment_counter(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 senderWallet.getTransactionCost(transactionRequest);

transactionRequest.gasLimit = txCost.gasUsed;
transactionRequest.maxFee = txCost.maxFee;

await senderWallet.fund(transactionRequest, txCost);

// Submit the transaction
const response = await senderWallet.sendTransaction(transactionRequest);
await response.waitForResult();
// Get result of contract call
const { value } = await buildFunctionResult({
  funcScope: scope,
  isMultiCall: false,
  program: contract,
  transactionResponse: response,
});
// <BN: 0x2710>

See code in context