Gift script evaluation failure

[juliusfrost]

I'm creating a simple gift script with pycardano and eopsin but I'm having issues redeeming from the script address.

I get the following error from my script:

pycardano.exception.TransactionFailedException: {'EvaluationFailure': {'ScriptFailures': {'spend:0': [{'nonScriptInputReferencedByRedeemer': {'txId': '4e52138675f6ee4a868ff24d49d61fd98234debd96fe93b09a535c6446e11cb0', 'index': 0}}]}}}
python-BaseException

Here's the code I use:

import click
from pycardano import OgmiosChainContext, Network, Address, TransactionBuilder, PaymentVerificationKey, \
    PaymentSigningKey, TransactionOutput, Transaction, UTxO, PlutusV2Script, plutus_script_hash, Redeemer, RedeemerTag, \
    PlutusData

from src.week02 import assets_dir

keys_dir = assets_dir.joinpath("../../../keys")


@click.command()
@click.argument("name")
def main(name):
    context = OgmiosChainContext("ws://localhost:1337", network=Network.TESTNET)
    with open(assets_dir.joinpath("gift", "testnet.addr")) as f:
        script_address = Address.from_primitive(f.read())

    with open(assets_dir.joinpath("gift", "script.cbor"), "r") as f:
        script_hex = f.read()

    gift_script = PlutusV2Script(bytes.fromhex(script_hex))
    script_hash = plutus_script_hash(gift_script)
    address = Address(script_hash, network=Network.TESTNET)
    assert script_address == address

    with open(keys_dir.joinpath(f"{name}.addr")) as f:
        payment_address = Address.from_primitive(f.read())

    utxo_to_spend = None
    for utxo in context.utxos(str(script_address)):
        utxo_to_spend = utxo
        break

    assert isinstance(utxo_to_spend, UTxO), "No UTxOs found!"

    redeemer = Redeemer(RedeemerTag.SPEND, 0)

    builder = TransactionBuilder(context)
    builder.add_script_input(utxo_to_spend, script=gift_script, datum=PlutusData(), redeemer=redeemer)
    amount = utxo_to_spend.output.amount - 2000000
    builder.add_output(
        TransactionOutput(address=payment_address, amount=amount)
    )
    non_nft_utxo = None
    for utxo in context.utxos(str(payment_address)):
        # multi_asset should be empty for collateral utxo
        if not utxo.output.amount.multi_asset:
            non_nft_utxo = utxo
            break
    builder.collaterals.append(non_nft_utxo)
    signed_tx = sign(builder, name)

    # context.submit_tx(signed_tx.to_cbor())
    print(f"transaction id: {signed_tx.id}")
    print(f"Cardanoscan: https://preview.cardanoscan.io/transaction/{signed_tx.id}")


def get_signing_info(name):
    vkey_path = str(keys_dir.joinpath(f"{name}.vkey"))
    skey_path = str(keys_dir.joinpath(f"{name}.skey"))
    payment_vkey = PaymentVerificationKey.load(vkey_path)
    payment_skey = PaymentSigningKey.load(skey_path)
    payment_address = Address(payment_vkey.hash(), network=Network.TESTNET)
    with open(keys_dir.joinpath(f"{name}.addr")) as f:
        address = Address.from_primitive(f.read())
    assert payment_address == address
    return payment_vkey, payment_skey, payment_address


def sign(builder: TransactionBuilder, name) -> Transaction:
    payment_vkey, payment_skey, payment_address = get_signing_info(name)
    return builder.build_and_sign(
        signing_keys=[payment_skey],
        change_address=payment_address,
    )


if __name__ == "__main__":
    main()

[juliusfrost]

It turns out I didn't send a datum in sending to the script address, and such transaction outputs are impossible to spend. See below,

                           TxHash                                 TxIx        Amount
--------------------------------------------------------------------------------------
4e52138675f6ee4a868ff24d49d61fd98234debd96fe93b09a535c6446e11cb0     0        5000000 lovelace + TxOutDatumNone