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

Create an empty transaction of type TxType.VALUE_TRANSFER_MEMO. 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

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

Finally, get the result.

ValueTransferWithMemo.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_value_transfer_with_memo_sign_recover():
    user = Account.from_key('0x0e4ca6d38096ad99324de0dde108587e5d7c600165ae4cd6c2462c597458c2b8')
    value_transfer_tx = empty_tx(TxType.VALUE_TRANSFER_MEMO)
    value_transfer_tx = merge(value_transfer_tx, {
        'from' : user.address,
        'to' : user.address,
        'value' : Web3.to_peb(0.1, 'klay'),
        'data' : b'TestMemoData'
    })
    value_transfer_tx = fill_transaction(value_transfer_tx, w3)
    # sign the kaia specific transaction type with web3py
    signed_tx = Account.sign_transaction(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)
    decoded_tx = Account.decode_transaction(signed_tx.rawTransaction)
    print("\ndecoded transaction:", to_pretty(decoded_tx))
    tx_hash = w3.eth.send_raw_transaction(signed_tx.rawTransaction)
    tx_receipt = w3.eth.wait_for_transaction_receipt(tx_hash)
    print('tx hash: ', tx_hash, 'receipt: ', tx_receipt)
web3_value_transfer_with_memo_sign_recover()

output


❯ node ValueTransferWithMemo.py
raw transaction of signed tx: 0x10f896820366850ba43b74008301042894a2a8854b1802d8cd5de631e690817c253d6a915388016345785d8a000094a2a8854b1802d8cd5de631e690817c253d6a91538c546573744d656d6f44617461f847f8458207f6a00daff49a09fbb8382654be6461d75e67def4d26442bf7bc8014da04d9d3b6f6da044fb682a3cd21e94e4dcf97cde1e0416d96dad2f15d353529a5db85873192c5b
recovered sender address 0xA2a8854b1802D8Cd5De631E690817c253d6a9153
decoded transaction: {
  "type": 16,
  "to": "0xA2a8854b1802D8Cd5De631E690817c253d6a9153",
  "value": 100000000000000000,
  "nonce": 870,
  "gasPrice": 50000000000,
  "gas": 66600,
  "from": "0xA2a8854b1802D8Cd5De631E690817c253d6a9153",
  "data": "0x546573744d656d6f44617461",
  "signatures": [
    {
      "v": 2038,
      "r": 6190953446910446010339588924128856456849311270962439470585054122192743919469,
      "s": 31201471237264490747209103173489052293037646153294155398956746212102253390939
    }
  ],
  "chainId": 1001
}
tx hash:  0x5b29f3dbc2f0d79dee4338a556eeb33c9d2dea9d0602882d44c307a2f25bce28 receipt:  AttributeDict({'blockHash': HexBytes('0x2ff2f47d724ccd645010adde8cebdb88edc4a31ffa415b34230f620544ecea6c'), 'blockNumber': 147340972, 'contractAddress': None, 'cumulativeGasUsed': 22200, 'effectiveGasPrice': 25000000000, 'from': '0xA2a8854b1802D8Cd5De631E690817c253d6a9153', 'gasUsed': 22200, 'logs': [], 'logsBloom': HexBytes('0x00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000'), 'status': 1, 'to': '0xA2a8854b1802D8Cd5De631E690817c253d6a9153', 'transactionHash': HexBytes('0x5b29f3dbc2f0d79dee4338a556eeb33c9d2dea9d0602882d44c307a2f25bce28'), 'transactionIndex': 0, 'type': 0})```