Passing am Option parameter has a payload.

[Pelumi527]

Please how do we pass an Option parameter has a payload?

[MoonShiesty]

i believe you can use MoveOption in an entry function payload. i dont see any examples of MoveOption in the ts-sdk examples and i haven't used MoveOption in payloads before, let me know if you run into any issues.

[0x-j]

+1, you can use option in entry function payload. Here's a simple example

    #[event]
    struct MyEvent has drop, store {
        text: String,
        user: address,
    }

    public entry fun test_option_param(user: &signer, option_s: Option<String>) {
        let s = option::borrow_with_default(&option_s, &utf8(b"hehe"));
        event::emit<MyEvent>(MyEvent {
            text: *s,
            user: address_of(user),
        });
    }

Here's how I call it with ts sdk

  const aptosConfig = new AptosConfig({
    network: Network.RANDOMNET,
  });
  const aptos = new Aptos(aptosConfig);

  const tx = await aptos.transaction.build.simple({
    sender: sender.accountAddress,
    data: {
      function: `${contract}::main::test_option_param`,
      typeArguments: [],
      // this will print hahaha in MyEvent
      functionArguments: ["hahaha"],
      // this will print default hehe in MyEvent
      // functionArguments: [undefined]
    },
  });
  const pendingTx = await aptos.signAndSubmitTransaction({
    signer: sender,
    transaction: tx,
  });
  const response = await aptos.waitForTransaction({
    transactionHash: pendingTx.hash,
  });
  console.log("tx hash. - ", response.hash);

[gregnazario]

Options as Entry function parameters

Depends on the SDK etc. Let's take this example entry function:

module 0x1337::module {
  entry fun do_stuff(caller: &signer, my_option: Option<u8>) {
    // Do something with the option
  }
}

TS SDK

There are two ways to encode it, either typed, or the easy mode, where it'll figure it out for you.

Easy mode: SDK will figure it out for you

The SDK will use the ABI, either provided or retrieved from on-chain to infer and try to
determine the proper encoding.

Here's for a Some(5) option:

    const num = 5; // Note must be between 0-255 for u8
    const txn = await aptos.transaction.build.simple({
        sender: account.accountAddress,
        data: {
            function: "0x1337::module::do_stuff",
            typeArguments: [],
            functionArguments: [num],
        }
    });

For a none option, you must include explicitly that there is no value. Here's for a None option:

    const txn = await aptos.transaction.build.simple({
        sender: account.accountAddress,
        data: {
            function: "0x1337::module::do_stuff",
            typeArguments: [],
            functionArguments: [undefined], // null will also work
        }
    });

Advanced mode: Encode arguments yourself

Sometimes, the inputs become really complex, and you want to encode it yourself, plus
it can be slightly more performant.

For Some(5) option:

    const num = 5; // Note must be between 0-255 for u8

    // Encode it as an option
    const option = new MoveOption(new U8(num)); 

    // This is also another shorthand option
    // const option = MoveOption.U8(num);

    const txn = await aptos.transaction.build.simple({
        sender: account.accountAddress,
        data: {
            function: "0x1337::module::do_stuff",
            typeArguments: [],
            functionArguments: [option],
        }
    });

For None option:

    // Encode it as an option
    const option = new MoveOption<U8>(undefined); 

    // This is also another shorthand option
    // const option = MoveOption.U8();

    const txn = await aptos.transaction.build.simple({
        sender: account.accountAddress,
        data: {
            function: "0x1337::module::do_stuff",
            typeArguments: [],
            functionArguments: [option],
        }
    });

CLI

In the CLI, you have to be closer to the definition in BCS (a single element array).

For a Some(5) option:

aptos move run --function-id 0x1337::module::do_stuff --args "u8:[5]"

For a None option:

aptos move run --function-id 0x1337::module::do_stuff --args "u8:[]"

How is it encoded in BCS (and entry function arguments)

Options are encoded as a single element vector in BCS. If the array is empty, the option is None if the option has a value, the option is Some. Any other amount in the array is invalid.

For example:

Some(5u8) => 0x0105
None() => 0x00

[Pelumi527]

Thanks.

[Pelumi527]

Thanks.

[Pelumi527]

Thanks.