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撰写（费用委托）

当您要执行智能合约时，您可以向 feepayer 发送**"交易 "，其中包括支付请求**。

导入**@kaiachain/viem-ext**软件包，在 web3 上添加 kaia 功能

初始化公共客户端，用于与 Kaia 区块链进行只读交互。

使用 createWalletClient，配置Kairos链、HTTP传输和转换为账户的发送方私钥，建立发送方和付费方钱包。

在至字段中设置要执行的合同地址，并设置ABI。

使用 encodeFunctionData 函数对函数名和参数进行编码

使用prepareTransactionRequest创建写入智能合约的交易请求，指定发送方账户、接收方地址、要转账的金额（本例中为 0 KLAY）和交易类型**(TxType.SmartContractExecution)**。

使用钱包客户端的 signTransaction 方法签署交易。

发送者使用 "klay_sendRawTransaction "向 Kaia 区块链提交交易，并记录结果（通常是交易哈希值）。汇款人支付交易费用。

准备一个费用委托事务（"FeeDelegatedSmartContractExecution"），以调用合同上相同的 "setNumber "函数。设置与非收费委托交易类似，但收费人在交易上签字，以**支付费用。

发送方首先签署交易，缴费方添加签名，然后将交易提交到 Kaia 区块链。

通过调用 number 函数（一个不修改状态的视图函数），使用公共客户端从合约中读取数字变量的值。

writeWithFeeDelegation.js


import {
    http,
    encodeFunctionData,
    createWalletClient, createPublicClient, kairos,
    TxType,
    privateKeyToAccount
} from "@kaiachain/viem-ext";
const publicClient = createPublicClient({
    chain: kairos,
    transport: http(),
});
const senderWallet = createWalletClient({
    chain: kairos,
    transport: http(),
    account: privateKeyToAccount(
        "0x0e4ca6d38096ad99324de0dde108587e5d7c600165ae4cd6c2462c597458c2b8"
    ),
})
const feePayerWallet = createWalletClient({
    chain: kairos,
    transport: http(),
    account: privateKeyToAccount(
        "0x9435261ed483b6efa3886d6ad9f64c12078a0e28d8d80715c773e16fc000cff4"
    ),
});
// Example usage
(async () => {
    const contractAddr = "0x95Be48607498109030592C08aDC9577c7C2dD505";
    const abi = [{ "inputs": [{ "internalType": "uint256", "name": "initNumber", "type": "uint256" }], "stateMutability": "nonpayable", "type": "constructor" }, { "anonymous": false, "inputs": [{ "indexed": false, "internalType": "uint256", "name": "number", "type": "uint256" }], "name": "SetNumber", "type": "event" }, { "inputs": [], "name": "increment", "outputs": [], "stateMutability": "nonpayable", "type": "function" }, { "inputs": [], "name": "number", "outputs": [{ "internalType": "uint256", "name": "", "type": "uint256" }], "stateMutability": "view", "type": "function" }, { "inputs": [{ "internalType": "uint256", "name": "newNumber", "type": "uint256" }], "name": "setNumber", "outputs": [], "stateMutability": "nonpayable", "type": "function" }];
    const data = encodeFunctionData({
        abi,
        args: [123n],
        functionName: "setNumber",
    });
    // non fee payer
    const tx = await senderWallet.prepareTransactionRequest({
        type: TxType.SmartContractExecution,
        account: senderWallet.account,
        to: contractAddr,
        value: 0,
        data,
    });
    console.log("preparedTx", tx);
    const signedTx = await senderWallet.signTransaction(tx);
    const sentTx = await senderWallet.request({
        method: "klay_sendRawTransaction",
        params: [signedTx],
    });
    console.log("contract interaction tx", sentTx);
    // fee payer
    const tx2 = await senderWallet.prepareTransactionRequest({
        type: TxType.FeeDelegatedSmartContractExecution,
        account: senderWallet.account,
        to: contractAddr,
        value: 0,
        data,
    });
    const signedTx2 = await senderWallet.signTransaction(tx2);
    const feePayerSignedTx = await feePayerWallet.signTransactionAsFeePayer(
        signedTx2
    );
    const sentFeePayerTx = await feePayerWallet.request({
        method: "klay_sendRawTransaction",
        params: [feePayerSignedTx],
    });
    console.log("fee payer contract execution tx", sentFeePayerTx);
    const result = await publicClient.readContract({
        address: contractAddr,
        abi,
        functionName: 'number'
    })
    console.log('Current contract value', result);
})();

output


❯ js writeWithFeeDelegation.js
preparedTx {
  type: 48,
  account: {
    address: '0xA2a8854b1802D8Cd5De631E690817c253d6a9153',
    nonceManager: undefined,
    sign: [AsyncFunction: sign],
    signAuthorization: [AsyncFunction: signAuthorization],
    signMessage: [AsyncFunction: signMessage],
    signTransaction: [AsyncFunction: signTransaction],
    signTypedData: [AsyncFunction: signTypedData],
    source: 'privateKey',
    type: 'local',
    publicKey: '0x04dc9dccbd788c00fa98f7f4082f2f714e799bc0c29d63f04d48b54fe6250453cdaf06ca34ae8714cf3dae06bacdb78c7c2d4054bd38961d40853cd5f15955da79'
  },
  to: '0x95Be48607498109030592C08aDC9577c7C2dD505',
  value: 0,
  data: '0x3fb5c1cb000000000000000000000000000000000000000000000000000000000000007b',
  from: '0xA2a8854b1802D8Cd5De631E690817c253d6a9153',
  nonce: 2400,
  chainId: 1001,
  gas: 27893n,
  gasPrice: '0x66720b300',
  gasLimit: 69732
}
contract interaction tx 0x67e3975188a4e7c221ac823450b51a4ac8064ddeb35523defd890b1559e0343d
fee payer contract execution tx 0xc63d64d49a95ecc9f0fa9a25e78a7df5192224d703f634a77a64123ed36ac97f
Current contract value 123n