Icon LinkMultiple contract calls

With CallHandler, you can execute multiple contract calls within a single transaction. To achieve this, you first prepare all the contract calls that you want to bundle:

let contract_methods = MyContract::new(contract_id, wallet.clone()).methods();
 
let call_handler_1 = contract_methods.initialize_counter(42);
let call_handler_2 = contract_methods.get_array([42; 2]);

You can also set call parameters, variable outputs, or external contracts for every contract call, as long as you don't execute it with call() or simulate().

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Note: if custom inputs or outputs have been added to the separate calls, the input and output order will follow the order how the calls are added to the multi-call.

Next, you provide the prepared calls to your CallHandler and optionally configure transaction policies:

let multi_call_handler = CallHandler::new_multi_call(wallet.clone())
    .add_call(call_handler_1)
    .add_call(call_handler_2)
    .with_tx_policies(TxPolicies::default());

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Note: any transaction policies configured on separate contract calls are disregarded in favor of the parameters provided to the multi-call CallHandler.

Furthermore, if you need to separate submission from value retrieval for any reason, you can do so as follows:

let submitted_tx = multi_call_handler.submit().await?;
tokio::time::sleep(Duration::from_millis(500)).await;
let (counter, array): (u64, [u64; 2]) = submitted_tx.response().await?.value;

Icon LinkOutput values

To get the output values of the bundled calls, you need to provide explicit type annotations when saving the result of call() or simulate() to a variable:

let (counter, array): (u64, [u64; 2]) = multi_call_handler.call().await?.value;

You can also interact with the CallResponse by moving the type annotation to the invoked method:

let response = multi_call_handler.call::<(u64, [u64; 2])>().await?;