Question

我正在运行web3 1.0.0-beta.27， pragma solidity ^ 0.4.2;

contract Charity{

    function ping() public constant returns (uint) {
        return 200;
    }


}

我在typescript编译/调用它：

import * as fs       from 'fs'       ;
import * as solc     from 'solc'     ;
import * as Web3     from 'web3'     ; 


var web3   = new Web3(new Web3.providers.WebsocketProvider('ws://localhost:8546'));

var contract_path : string = "path/to/Charity.sol"
const input       = fs.readFileSync(contract_path)
const output      = solc.compile(input.toString(), 1);
var contract_name = ":" + pr.last(contract_path.split("/")).split(".")[0]
const bytecode    = output.contracts[contract_name].bytecode
const abi_        = JSON.parse(output.contracts[contract_name].interface);

web3.eth.getAccounts().then(accounts => {

    var coinbase = accounts[0];
    var receiver = accounts[1];

    // create contract
    var myContract = new web3.eth.Contract([], {
          from     : coinbase
        , gasPrice : '20000000000'
    });

    // set address to coinbase, and jsonInterface to abi
    myContract.options.address = coinbase;
    myContract.options.jsonInterface = abi_;

    // deploy contract -> problem, how do I get the abi in here?
    var deployedContract = myContract.deploy({

        data: '0x' + bytecode,

    }).send({

        from: coinbase,
        gas : 1500000 ,
        gasPrice: '30000000000000'            

    }, (err, hash) => {

        if (err) { console.log("error on deployment: ", err) }
        console.log("Hash: ", hash)
    })

    // send contract fn to network to be executed
    // problem: this is not doing what it's suppose to 
    myContract.methods.ping().send({ from : coinbase }, (err, val) => {
        console.log("ping(): ", err, val)
    })

    myContract.methods.ping().send({from: coinbase})
    .on('transactionHash', function(hash){
        console.log("hash: ", hash)
    })
    .on('receipt', function(receipt){
        console.log("recepit: ", receipt)
    })
    .on('confirmation', function(confirmationNumber, receipt){
        console.log("conffirmation: ", receipt)
    })
    .on('error', console.error);        



});

问题是myContract.methods.ping().send...没有按照我的意愿在回调中返回值200，有没有办法解决这个问题？

Answer 1

调用常量函数后，应使用调用（）而不是 send（）方法。

检查文档： http://web3js.readthedocs.io/en/1.0/web3-eth-contract.html#methods-mymethod-call

Answer 2

当您不修改状态时，只需使用call（）。如果您修改状态，则需要进行交易（发送），然后需要等待交易被挖掘。这样做的方法是发出一个事件并监听它。

从web3-1.0.0-beta.27获取Solidity contract函数的返回值

2 个答案: