Value Transfer Memo

TxTypeValueTransferMemo is used when a user wants to send KAIA with a specific message.

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 value into the empty tx by using the merge util.

You can use the Web3.to_peb util to convert decimal

Especially write down what you want to record in the data field in a binary format

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 transaction as the fee payer.

Recover the fee payer's address from the signed transaction.

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

FeeDelegatedValueTransferMemo.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_value_transfer_with_memo_sign_recover():
    user = Account.from_key('0x0e4ca6d38096ad99324de0dde108587e5d7c600165ae4cd6c2462c597458c2b8')
    fee_delegator = Account.from_key('0x9435261ed483b6efa3886d6ad9f64c12078a0e28d8d80715c773e16fc000cff4')
    fee_delegated_value_transfer_tx = empty_tx(TxType.FEE_DELEGATED_VALUE_TRANSFER_MEMO)
    fee_delegated_value_transfer_tx = merge(fee_delegated_value_transfer_tx, {
        'from' : user.address,
        'to' : user.address,
        'value' : Web3.to_peb(0.1, 'klay'),
        'data' : 'memo'.encode(encoding='utf-8').hex(),
    })
    fee_delegated_value_transfer_tx = fill_transaction(fee_delegated_value_transfer_tx, w3)
    # sign the kaia specific transaction type with web3py
    signed_tx = Account.sign_transaction(fee_delegated_value_transfer_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 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_value_transfer_with_memo_sign_recover()

output


❯ python FeeDelegatedValueTransferMemo.py
raw transaction of signed tx: 0x11f88d8203a2850ba43b740082fac894a2a8854b1802d8cd5de631e690817c253d6a915388016345785d8a000094a2a8854b1802d8cd5de631e690817c253d6a9153846d656d6ff847f8458207f5a03d5781735b63e147a6cdb4c5f4d9371b87a776ed6b2460997799cf82a4c5dc6ca07beeefc1f5ccd72a994e65b8fa5cbafda79046383530d2d81c5e128bb6032c5c
recovered sender address 0xA2a8854b1802D8Cd5De631E690817c253d6a9153
raw transaction of signed tx: 0x11f8eb8203a2850ba43b740082fac894a2a8854b1802d8cd5de631e690817c253d6a915388016345785d8a000094a2a8854b1802d8cd5de631e690817c253d6a9153846d656d6ff847f8458207f5a03d5781735b63e147a6cdb4c5f4d9371b87a776ed6b2460997799cf82a4c5dc6ca07beeefc1f5ccd72a994e65b8fa5cbafda79046383530d2d81c5e128bb6032c5c94cb0eb737dfda52756495a5e08a9b37aab3b271daf847f8458207f6a050f32b7e60dd18c6ff122f6bdc94f831b5912de7e1cfb6b291b8a2458ccdbe69a03153156ec7a8bbb51dbcb0d40a717cdc31173ef748f6803418af26b66e40e57f
recovered feepayer address: ['0xCb0eb737dfda52756495A5e08A9b37AAB3b271dA']
decoded transaction: {
  "type": 17,
  "to": "0xA2a8854b1802D8Cd5De631E690817c253d6a9153",
  "value": 100000000000000000,
  "nonce": 930,
  "gasPrice": 50000000000,
  "gas": 64200,
  "from": "0xA2a8854b1802D8Cd5De631E690817c253d6a9153",
  "data": "0x6d656d6f",
  "feePayer": "0xCb0eb737dfda52756495A5e08A9b37AAB3b271dA",
  "signatures": [
    {
      "v": 2037,
      "r": 27745692893512078622955272339665478959198598054588520658281796167915765357676,
      "s": 56056644723691388895475112662977851531398597373084653396908548095691232324700
    }
  ],
  "feePayerSignatures": [
    {
      "v": 2038,
      "r": 36614671905649584459785163916244052559136997622248050659604331627579687419497,
      "s": 22310125810250633785807423340835226393398279220715112280506580747244212905343
    }
  ],
  "chainId": 1001
}
tx hash:  0xe9d6214c30b433cd7bb3bc3a37afad86fba4b4153bbc08607a44b390fd015c36 receipt:  AttributeDict({'blockHash': HexBytes('0xdcc51fb57ca4d010ea14d46a18d1ad1eabf9fef90b2fe002902796f59ed3a4dc'), 'blockNumber': 148223370, 'contractAddress': None, 'cumulativeGasUsed': 31400, 'effectiveGasPrice': 25000000000, 'from': '0xA2a8854b1802D8Cd5De631E690817c253d6a9153', 'gasUsed': 31400, 'logs': [], 'logsBloom': HexBytes('0x00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000'), 'status': 1, 'to': '0xA2a8854b1802D8Cd5De631E690817c253d6a9153', 'transactionHash': HexBytes('0xe9d6214c30b433cd7bb3bc3a37afad86fba4b4153bbc08607a44b390fd015c36'), 'transactionIndex': 0, 'type': 0})