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Smart Contract Execution

TxTypeSmartContractExecution executes a smart contract with the given data. TxTypeSmartContractExecution is accepted only if "to" is a smart contract account.

Import extend from web3py_ext to extend web3 to kaia web3

Import necessary utils from eth_account, web3py_ext and cytoolz

Create a Web3 instance with the specified kairos testnet URL

Also, you can change the provider URL from kairos to quicknode

Load an account from private key

Load a fee payer account from private key

Create an empty transaction of type TxType.FEE_DELEGATED_SMART_CONTRACT_EXECUTION. You can use empty_tx util to get a tx with default fields filled.

Merge the additional fields like from, to and data into the empty tx by using the merge util.

Set the contract address you want to execute into the to field

In this tutorial, the data to call a function of the contract is encoded into bytes stream. Please refer to the write tutorial in the Smart Contract section to make the encoded data

Use fill_transaction to add more params to transaction object like gas limit...

Sign the value transfer tx by user's private key

Recover the signer's address from the signature in signed tx

Sign the value transfer tx by fee payer's private key

Recover the fee payer's address from the signature in signed tx

You can decode the RLP-encoded tx by the Account.decode_transaction util and if you want to make the output format pretty, use the to_pretty util

Send the tx to the blockchain. It will return the tx hash, which will be used to wait the receipt

The wait_for_transaction_receipt method returns the tx receipt if it is completed in the blockchain

delegated_smart_contract_execution_sign_recover.py


from web3py_ext import extend
from web3 import Web3
from eth_account import Account
from web3py_ext.transaction.transaction import (
    empty_tx,
    fill_transaction,
    TxType
)
from web3py_ext.utils.klaytn_utils import to_pretty
from cytoolz import merge
w3 = Web3(Web3.HTTPProvider('https://public-en-kairos.node.kaia.io'))
def web3_fee_delegated_smart_contract_execution_sign_recover():
    user = Account.from_key('0x0e4ca6d38096ad99324de0dde108587e5d7c600165ae4cd6c2462c597458c2b8')
    fee_delegator = Account.from_key('0x9435261ed483b6efa3886d6ad9f64c12078a0e28d8d80715c773e16fc000cff4')
    smart_contract_execution_tx = empty_tx(TxType.FEE_DELEGATED_SMART_CONTRACT_EXECUTION)
    smart_contract_execution_tx = merge(smart_contract_execution_tx, {
        'from' : user.address,
        'to' : '0x108bF12b50c9ef65525F0495C721aEc55015e111', # already deployed contract for test before
        'data' : '0x3d7403a30000000000000000000000000000000000000000000000000000000000000020000000000000000000000000000000000000000000000000000000000000000c48656c6c6f204b6c6179746e0000000000000000000000000000000000000000',
    })
    smart_contract_execution_tx = fill_transaction(smart_contract_execution_tx, w3)
    # sign the kaia specific transaction type with web3py
    signed_tx = Account.sign_transaction(smart_contract_execution_tx, user.key)
    print("\nraw transaction of signed tx:", signed_tx.rawTransaction.hex())
    recovered_tx = Account.recover_transaction(signed_tx.rawTransaction)
    print("\nrecovered sender address", recovered_tx)
    feepayer_signed_tx = Account.sign_transaction_as_feepayer(signed_tx.rawTransaction, fee_delegator.address, fee_delegator.key)
    print("\nraw transaction of feePayer signed tx:", feepayer_signed_tx.rawTransaction.hex())
    feepayer_recovered_tx = Account.recover_transaction_as_feepayer(feepayer_signed_tx.rawTransaction)
    print("recovered feepayer address:", feepayer_recovered_tx)
    decoded_tx = Account.decode_transaction(feepayer_signed_tx.rawTransaction)
    print("\ndecoded transaction:", to_pretty(decoded_tx))
    tx_hash = w3.eth.send_raw_transaction(feepayer_signed_tx.rawTransaction)
    tx_receipt = w3.eth.wait_for_transaction_receipt(tx_hash)
    print('tx hash: ', tx_hash, 'receipt: ', tx_receipt)
web3_fee_delegated_smart_contract_execution_sign_recover()

output


❯ py delegated_smart_contract_execution_sign_recover.py
raw transaction of signed tx: 0x31f8e78203a3850ba43b74008301b05d94108bf12b50c9ef65525f0495c721aec55015e1118094a2a8854b1802d8cd5de631e690817c253d6a9153b8643d7403a30000000000000000000000000000000000000000000000000000000000000020000000000000000000000000000000000000000000000000000000000000000c48656c6c6f204b6c6179746e0000000000000000000000000000000000000000f847f8458207f5a00a3db2a6793df0b256e2a81bce7ae3780783fcf58cc8326a14371c3413f3075da05031fd033453cf9a7be888b1db3812193d00221e299b483aa4e80a850664618a
recovered sender address 0xA2a8854b1802D8Cd5De631E690817c253d6a9153
raw transaction of feePayer signed tx: 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
recovered feepayer address: ['0xCb0eb737dfda52756495A5e08A9b37AAB3b271dA']
decoded transaction: {
  "type": 49,
  "value": 0,
  "gasPrice": 50000000000,
  "nonce": 931,
  "gas": 110685,
  "to": "0x108bF12b50c9ef65525F0495C721aEc55015e111",
  "from": "0xA2a8854b1802D8Cd5De631E690817c253d6a9153",
  "data": "0x3d7403a30000000000000000000000000000000000000000000000000000000000000020000000000000000000000000000000000000000000000000000000000000000c48656c6c6f204b6c6179746e0000000000000000000000000000000000000000",
  "feePayer": "0xCb0eb737dfda52756495A5e08A9b37AAB3b271dA",
  "signatures": [
    {
      "v": 2037,
      "r": 4632139155753288816177914350449378738873058722929189649296670464490515662685,
      "s": 36273349621051746908322095917532842606006460166655513683041721600219371823498
    }
  ],
  "feePayerSignatures": [
    {
      "v": 2037,
      "r": 59008994161645925359182568890805662549212009998969311671295364669364719147680,
      "s": 48760043609336873845154832650749116609475268552379125539006421213296675173404
    }
  ],
  "chainId": 1001
}
tx hash:  0x3569f46bb885eb4c849e10009ec7096530fa44ef7ee1287df83820fcef8d0ebd receipt:  AttributeDict({'blockHash': HexBytes('0x83d5276dc3fec557740a2d25c8f076aba11c022e7021b71bd95a76318c4ff5c9'), 'blockNumber': 148225895, 'contractAddress': None, 'cumulativeGasUsed': 44742, 'effectiveGasPrice': 25000000000, 'from': '0xA2a8854b1802D8Cd5De631E690817c253d6a9153', 'gasUsed': 44742, 'logs': [], 'logsBloom': HexBytes('0x00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000'), 'status': 1, 'to': '0x108bF12b50c9ef65525F0495C721aEc55015e111', 'transactionHash': HexBytes('0x3569f46bb885eb4c849e10009ec7096530fa44ef7ee1287df83820fcef8d0ebd'), 'transactionIndex': 0, 'type': 0})