How to add multiple recipients to a transaction?

[starkdm]

The code below demonstrates creating a transaction, but with only one recipient (TransactionBuilder.Send). How to add multiple recipients to a transaction?

TransactionBuilder builder = Network.TestNet.CreateTransactionBuilder();
builder.AddCoins(unspentCoins);
builder.SendEstimatedFees(new FeeRate(rate));
builder.AddKeys(privateKey);
builder.SetChange(address);
builder.Send(receiver, new Money(money));
Transaction transaction = builder.BuildTransaction(true);

[ArtjomP]

Just add a new Send line builder.Send(receiver2, new Money(money2))

[starkdm]

The previous recipient will be replaced. As a result, one output is obtained. Check it.

[ArtjomP]

Strange. It works well for me. Check the Outputs of the built transaction

[starkdm]

Apparently the problem is that I set a very small output value. If the value is less than 294 satoshi, TransactionBuilder does not add a transaction output. Why is there such a limitation?

[yahiheb]

For P2WPKH (native segwit) outputs, 293 satoshis or smaller are being considered dust

https://bitcoin.stackexchange.com/questions/10986/what-is-meant-by-bitcoin-dust

[starkdm]

Thanks!

[knocte]

I wonder if this should fail with an exception named AmountLessThanDustException or something, instead of failing silently?

[lontivero]

It doesn't fail silently, it is configured to work in that way. You can switch the DustPrevention to false to make it work in the other way.

[knocte]

DustPrevention=true fails silently and DustPrevention=false doesn't throw an exception when using less than dust. To me, it means both options fail silently. There should be a way for the developer to know if dust limit was violated or not without having to check if number of inputs didn't increase after adding one.

[knocte]

@NicolasDorier how about a PR that changes that setting from bool to an enum like:

enum DustPrevention {
    DiscardInputs, // equivalent to "true", the current default
    Throw, // would throw an exception if input added is smaller than dust
    None
}