将已签名的交易发送到 Ropsten

Question

使用 web3js 很容易调用不需要签名的函数（例如不更新合约状态的函数）。但是，除了手动解锁我的 MetaMask 钱包和在Remix环境中调用函数之外，尚不清楚如何调用需要签名的函数。

在第一次将我的 dapp 部署到 Ropsten 之后，我需要调用createItem(string name, uint price)100 次来items最初填充数组。由于我不想在 Remix 中手动执行此操作，因此我想编写一个自动执行此操作的脚本。

看起来我还需要ethereumjs-tx在web3js没有 MetaMask 的情况下以编程方式签署交易。我还需要有我的account和privateKey。有了所有这些信息和官方的 web3js 文档，我想出了以下内容：

// Call an external function programatically

const web3 = new Web3(new Web3.providers.HttpProvider("https://ropsten.infura.io"))
const account = "ACCOUNT_ADDRESS"
const privateKey = new Buffer('PRIVATE_KEY', 'hex')
const contract = new web3.eth.Contract(abi, CONTRACT_ADDRESS, {
  from: account,
  gas: 3000000,
})

const functionAbi = contract.methods.myFunctionName(myArgument).encodeABI()

let estimatedGas
contract.methods.myFunctionNAme(myArgument).estimateGas({
  from: account,
}).then((gasAmount) => {
  estimatedGas = gasAmount.toString(16)
})

const txParams = {
  gasPrice: '0x' + estimatedGas,
  to: CONTRACT_ADDRESS,
  data: functionAbi,
  from: account,
}

const tx = new Tx(txParams)
tx.sign(privateKey)

const serializedTx = tx.serialize()

web3.eth.sendSignedTransaction('0x' + serializedTx.toString('hex')).
  on('receipt', console.log)

代码运行，但txParams实际上缺少一个键：nonce. 运行此程序时，您会收到以下错误：

Unhandled rejection Error: Returned error: nonce too low

以下是我的问题：

1. 这通常是做我想做的事情的正确方法吗？
2. 如果 1 为真，我如何获取已nonce部署合约的参数？

参考：

1. http://web3js.readthedocs.io/en/1.0/
2. https://github.com/ethereumjs/ethereumjs-tx
3. https://ethereum.stackexchange.com/questions/21402/web3-eth-call-how-can-i-set-data-param
4. https://ethereum.stackexchange.com/questions/6368/using-web3-to-sign-a-transaction-without-connecting-to-geth

更新：

感谢 Adam，现在我学会了如何获取nonce. 所以我添加了以下代码：

let nonce
web3.eth.getTransactionCount(account).then(_nonce => {
  nonce = _nonce.toString(16)
})

const txParams = {
  gasPrice: '0x' + gasPrice,
  to: CONTRACT_ADDRESS,
  data: functionAbi,
  from: account,
  nonce: '0x' + nonce,
}

但现在我不断遇到这个异常：

未处理的拒绝错误：返回错误：rlp：输入字符串对于 uint64 来说太长，解码为 (types.Transaction)(types.txdata).AccountNonce

除了让我找到这个具有异常处理程序的文件（https://github.com/ethereum/go-ethereum/blob/master/rlp/decode.go）之外，谷歌搜索没有帮助。有谁知道如何解决这个问题？

Answer 1

一般看起来是正确的。我唯一的问题是你打算如何加载私钥？您需要提示输入私钥，或者在密钥库中导入/读取并提示输入密码。您可以使用keythereum来完成此操作（有关示例代码，请参阅密钥导入部分）。

这nonce只是用于为帐户订购交易的增量编号。要获得正确的值，只需使用web3.eth.getTransactionCount(account)

编辑 - 使用带有锁定帐户的 Ganache 运行示例（--secure选项）：

简单合同.sol

pragma solidity ^0.4.19;

contract SimpleContract {
  uint public val = 4;

  function increment(uint amt) public {
    val += amt;
  }

  function get() public constant returns (uint) {
    return  val;
  }
}

测试.js

const Web3 = require('web3');
const Tx = require('ethereumjs-tx');

const provider = new Web3.providers.HttpProvider("http://localhost:8545");
const web3 = new Web3(provider);

const account = '0x9a6d82ef3912d5ab60473124bccd2f2a640769d7'; // Ganache
const privateKey = Buffer.from('70f1384b24df3d2cdaca7974552ec28f055812ca5e4da7a0ccd0ac0f8a4a9b00', 'hex');
const contractAddress = '0x6dd7c1c13df7594c27e0d191fd8cc21efbfc98b4'; // Deployed manually
const abi = [{"constant":true,"inputs":[],"name":"val","outputs":[{"name":"","type":"uint256"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":true,"inputs":[],"name":"get","outputs":[{"name":"","type":"uint256"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":false,"inputs":[{"name":"amt","type":"uint256"}],"name":"increment","outputs":[],"payable":false,"stateMutability":"nonpayable","type":"function"}];

const contract = new web3.eth.Contract(abi, contractAddress, {
  from: account,
  gasLimit: 3000000,
});

const contractFunction = contract.methods.increment(3);

const functionAbi = contractFunction.encodeABI();

let estimatedGas;
let nonce;

console.log("Getting gas estimate");

contractFunction.estimateGas({from: account}).then((gasAmount) => {
  estimatedGas = gasAmount.toString(16);

  console.log("Estimated gas: " + estimatedGas);

  web3.eth.getTransactionCount(account).then(_nonce => {
    nonce = _nonce.toString(16);

    console.log("Nonce: " + nonce);
    const txParams = {
      gasPrice: '0x09184e72a000',
      gasLimit: 3000000,
      to: contractAddress,
      data: functionAbi,
      from: account,
      nonce: '0x' + nonce
    };

    const tx = new Tx(txParams);
    tx.sign(privateKey);

    const serializedTx = tx.serialize();

    contract.methods.get().call().then(v => console.log("Value before increment: " + v));

    web3.eth.sendSignedTransaction('0x' + serializedTx.toString('hex')).on('receipt', receipt => {
      console.log(receipt);
      contract.methods.get().call().then(v => console.log("Value after increment: " + v));
    })
  });
});

结果：

$ npm run my_test

> hello_world_dapp@1.0.0 my_test C:\cygwin\home\adamk\eth\hello_world_dapp
> node ./test.js

Getting gas estimate
Estimated gas: 6919
Nonce: 5
Value before increment: 19
{ transactionHash: '0xb6fdfc36cc32cb01a2be8832a387da586a44a37c1241bbf2979745536f206ed4',
  transactionIndex: 0,
  blockHash: '0xb6ee8d4e45585010d9a12d48aa37a478eb6021aad78599f1719cb424ab364bb5',
  blockNumber: 10,
  gasUsed: 26905,
  cumulativeGasUsed: 26905,
  contractAddress: null,
  logs: [],
  status: 1 }
Value after increment: 22