从node.js调用已部署的智能合约
我有一个小testing智能合同，这是部署到我的testingnetworking。 我想用服务器来调用合同中的函数。 这是代码：payontime.sol
pragma solidity ^0.4.0; contract payontime{ address public remitter; address private remittee; uint value; bool public start; /*Only owner can use these function*/ modifier onlyOwner(){ if(msg.sender != remitter) throw; _; } /*Initialize the owner*/ function payontime(address receiver) payable{ remitter = msg.sender; value = msg.value; remittee = receiver; start = true; if(!remittee.send(value)){ throw; } } function wakeUp() public returns (string){ return "success" ; } function getContractAddr() public returns(address){ return this; } /*Get the remittee*/ function getRemitee() public returns(address){ return remittee; } } 我用truffle serve和一个网页新的合同。
app.js
import { default as Web3} from 'web3'; import { default as contract } from 'truffle-contract' import payontime_artifacts from '../../build/contracts/payontime.json' var payontime = contract(payontime_artifacts); window.App = { sendCoin : function(){ var sender = web3.eth.accounts[0]; var receiver = document.getElementById('receiver').value; var amount = parseInt(document.getElementById('amount').value); web3.eth.getBalance(receiver,function(error,result){ if(!error){ consol.log("Before transfer: " + result ); }else{ console.log("Error: " + error); } }); var newContract = payontime.new(receiver,{from:sender, value:amount}).then( function(myPay){ console.log(myPay.getContractAddr.call()); }).then( function(){ web3.eth.getBalance(receiver,function(error,result){ if(!error){ console.log("After transfer: " + result ); }else{ console.log("Error: " + error); } }); }); } } window.addEventListener('load', function() { // Checking if Web3 has been injected by the browser (Mist/MetaMask) if (typeof web3 !== 'undefined') { console.warn("Using web3 detected from external source. If you find that your accounts don't appear or you have 0 MetaCoin, ensure you've configured that source properly. If using MetaMask, see the following link. Feel free to delete this warning. :) http://truffleframework.com/tutorials/truffle-and-metamask") // Use Mist/MetaMask's provider window.web3 = new Web3(web3.currentProvider); } else { console.warn("No web3 detected. Falling back to http://localhost:8545. You should remove this fallback when you deploy live, as it's inherently insecure. Consider switching to Metamask for development. More info here: http://truffleframework.com/tutorials/truffle-and-metamask"); // fallback - use your fallback strategy (local node / hosted node + in-dapp id mgmt / fail) window.web3 = new Web3(new Web3.providers.HttpProvider("http://localhost:8545")); } payontime.setProvider(web3.currentProvider); });
app.jslogging地址0x1d379f2ab48ad20319e9f81cb45af415aa6f2966 ，我想用这个地址通过另一个应用程序index.js调用wakeUp() 。
const Web3 = require('web3'); /* Connect to ethereum node */ const etherUrl = "http://localhost:8545"; const abi = [{"constant":false,"inputs":[],"name":"wakeUp","outputs":[{"name":"","type":"string"}],"payable":false,"type":"function"},{"constant":false,"inputs":[],"name":"getContractAddr","outputs":[{"name":"","type":"address"}],"payable":false,"type":"function"},{"constant":true,"inputs":[],"name":"remitter","outputs":[{"name":"","type":"address"}],"payable":false,"type":"function"},{"constant":true,"inputs":[],"name":"start","outputs":[{"name":"","type":"bool"}],"payable":false,"type":"function"},{"constant":false,"inputs":[],"name":"getRemitee","outputs":[{"name":"","type":"address"}],"payable":false,"type":"function"},{"inputs":[{"name":"receiver","type":"address"}],"payable":true,"type":"constructor"}]; let web3 = new Web3(); web3.setProvider(new web3.providers.HttpProvider(etherUrl)); /*Call the function which already deployed on ethereum network Notice: ABI have to modifeid when the smart contract code change*/ var contractInstance = web3.eth.contract(abi).at('0x1d379f2ab48ad20319e9f81cb45af415aa6f2966'); var reply = "false"; reply = contractInstance.wakeUp.call(function(error,result){ if(error){ console.log("Error"); throw error; }else{ return result; } }); console.log(reply);
但是有一个错误消息： BigNumber Error: new BigNumber() not a base 16 number我发现它可能是由未完全同步引起的。 我认为在部署合同中调用函数时会遇到一些问题。 那么我怎样才能从web.js中调用已部署的合同呢？
contractInstance.wakeUp.call将函数作为常量调用，但函数没有定义为常量：
function wakeUp() public returns (string){ return "success" ; }
必须：
function wakeUp() public constant returns (string){ return "success" ; }
如果您的Solidity函数不改变区块链状态并且只是读取数据，您应该将其定义为常量。
除了将您的控制台日志放在callback中，您还可以通过以下方法修复大数字错误：
console.log(result.toNumber());