使用 web3 ethereum 调用智能合约方法

Question

尝试使用以太坊解决区块链问题时，我在尝试与已部署的合约交互时遇到了问题。我想要实现的是调用一种方法来显示添加到使用 Geth 本地部署的私有区块链的信息。

我无法从我的智能合约中调用任何函数，我一直在想我是否做错了什么...有人可以告诉我如何实现对该合约中方法之一的简单调用？让我们说显示现有机构，或用户所属的机构名称。

我的合同：agency.sol

pragma solidity ^0.4.18;
// We have to specify what version of compiler this code will compile with

contract Agency {

  event NewAgency(uint agencyId, string name, uint dna);

  uint dnaDigits = 16;
  uint dnaModulus = 10 ** dnaDigits;

  //agency structure
  struct Agency {
    string name;
    uint dna;
  }

  Agency[] public agencies;

  mapping (uint => address) public agencyToOwner;
  mapping (address => uint) ownerAgencyCount;

  function _createAgency(string _name, uint _dna) private {
    uint id = agencies.push(Agency(_name, _dna)) - 1;
    agencyToOwner[id] = msg.sender;
    ownerAgencyCount[msg.sender]++;
    NewAgency(id, _name, _dna);
  } 

  function _generateRandomDna(string _str) private view returns (uint) {
    uint rand = uint(keccak256(_str));
    return rand % dnaModulus;
  }

  function createRandomAgency(string _name) public {
    //make sure contract can only execute if user is not part of an agency
    require(ownerAgencyCount[msg.sender] == 0);
    uint randDna = _generateRandomDna(_name);
    _createAgency(_name, randDna);
  }
}

abi定义

> abiDefinition
[ { constant: true,
    inputs: [ [Object] ],
    name: 'agencies',
    outputs: [ [Object], [Object] ],
    payable: false,
    stateMutability: 'view',
    type: 'function' },
  { constant: true,
    inputs: [ [Object] ],
    name: 'agencyToOwner',
    outputs: [ [Object] ],
    payable: false,
    stateMutability: 'view',
    type: 'function' },
  { constant: false,
    inputs: [ [Object] ],
    name: 'createRandomAgency',
    outputs: [],
    payable: false,
    stateMutability: 'nonpayable',
    type: 'function' },
  { anonymous: false,
    inputs: [ [Object], [Object], [Object] ],
    name: 'NewAgency',
    type: 'event' } ]

部署成功：

INFO [01-09|19:09:14] Submitted contract creation              fullhash=0x7c43e896329138a6778938ca30d2f5f17f9a63062b359a4fccbd1a1be439f385 contract=0x65175d22C56E1Bad976A331A8B6B448cd4B3995d

最后 contractInstance:

> contractInstance = AgencyContract.at(0x65175d22C56E1Bad976A331A8B6B448cd4B3995d)
Contract {
  _eth: 
   Eth {
     _requestManager: RequestManager { provider: [Object], polls: {}, timeout: null },
     getBalance: { [Function: send] request: [Function: bound ], call: 'eth_getBalance' },
     getStorageAt: { [Function: send] request: [Function: bound ], call: 'eth_getStorageAt' },
     getCode: { [Function: send] request: [Function: bound ], call: 'eth_getCode' },
     getBlock: { [Function: send] request: [Function: bound ], call: [Function: blockCall] },
     getUncle: { [Function: send] request: [Function: bound ], call: [Function: uncleCall] },
     getCompilers: { [Function: send] request: [Function: bound ], call: 'eth_getCompilers' },
     getBlockTransactionCount: 
      { [Function: send]
        request: [Function: bound ],
        call: [Function: getBlockTransactionCountCall] },
     getBlockUncleCount: 
      { [Function: send]
        request: [Function: bound ],
        call: [Function: uncleCountCall] },
     getTransaction: 
      { [Function: send]
        request: [Function: bound ],
        call: 'eth_getTransactionByHash' },
     getTransactionFromBlock: 
      { [Function: send]
        request: [Function: bound ],
        call: [Function: transactionFromBlockCall] },
     getTransactionReceipt: 
      { [Function: send]
        request: [Function: bound ],
        call: 'eth_getTransactionReceipt' },
     getTransactionCount: { [Function: send] request: [Function: bound ], call: 'eth_getTransactionCount' },
     call: { [Function: send] request: [Function: bound ], call: 'eth_call' },
     estimateGas: { [Function: send] request: [Function: bound ], call: 'eth_estimateGas' },
     sendRawTransaction: { [Function: send] request: [Function: bound ], call: 'eth_sendRawTransaction' },
     signTransaction: { [Function: send] request: [Function: bound ], call: 'eth_signTransaction' },
     sendTransaction: { [Function: send] request: [Function: bound ], call: 'eth_sendTransaction' },
     sign: { [Function: send] request: [Function: bound ], call: 'eth_sign' },
     compile: { solidity: [Object], lll: [Object], serpent: [Object] },
     submitWork: { [Function: send] request: [Function: bound ], call: 'eth_submitWork' },
     getWork: { [Function: send] request: [Function: bound ], call: 'eth_getWork' },
     coinbase: [Getter],
     getCoinbase: { [Function: get] request: [Function: bound ] },
     mining: [Getter],
     getMining: { [Function: get] request: [Function: bound ] },
     hashrate: [Getter],
     getHashrate: { [Function: get] request: [Function: bound ] },
     syncing: [Getter],
     getSyncing: { [Function: get] request: [Function: bound ] },
     gasPrice: [Getter],
     getGasPrice: { [Function: get] request: [Function: bound ] },
     accounts: [Getter],
     getAccounts: { [Function: get] request: [Function: bound ] },
     blockNumber: [Getter],
     getBlockNumber: { [Function: get] request: [Function: bound ] },
     protocolVersion: [Getter],
     getProtocolVersion: { [Function: get] request: [Function: bound ] },
     iban: 
      { [Function: Iban]
        fromAddress: [Function],
        fromBban: [Function],
        createIndirect: [Function],
        isValid: [Function] },
     sendIBANTransaction: [Function: bound transfer] },
  transactionHash: null,
  address: 5.771290982673958e+47,
  abi: 
   [ { constant: true,
       inputs: [Array],
       name: 'agencies',
       outputs: [Array],
       payable: false,
       stateMutability: 'view',
       type: 'function' },
     { constant: true,
       inputs: [Array],
       name: 'agencyToOwner',
       outputs: [Array],
       payable: false,
       stateMutability: 'view',
       type: 'function' },
     { constant: false,
       inputs: [Array],
       name: 'createRandomAgency',
       outputs: [],
       payable: false,
       stateMutability: 'nonpayable',
       type: 'function' },
     { anonymous: false,
       inputs: [Array],
       name: 'NewAgency',
       type: 'event' } ],
  agencies: 
   { [Function: bound ]
     request: [Function: bound ],
     call: [Function: bound ],
     sendTransaction: [Function: bound ],
     estimateGas: [Function: bound ],
     getData: [Function: bound ],
     uint256: [Circular] },
  agencyToOwner: 
   { [Function: bound ]
     request: [Function: bound ],
     call: [Function: bound ],
     sendTransaction: [Function: bound ],
     estimateGas: [Function: bound ],
     getData: [Function: bound ],
     uint256: [Circular] },
  createRandomAgency: 
   { [Function: bound ]
     request: [Function: bound ],
     call: [Function: bound ],
     sendTransaction: [Function: bound ],
     estimateGas: [Function: bound ],
     getData: [Function: bound ],
     string: [Circular] },
  allEvents: [Function: bound ],
  NewAgency: { [Function: bound ] 'uint256,string,uint256': [Function: bound ] } }

我试过：

contractInstance.agencies()
contractInstance.agencies.call()
contractInstance.agencies.call({from:ak})

结果 Error: Invalid number of arguments to Solidity function

contractInstance.agencies.call("name" {from:ak})

结果 Error: invalid address 我也尝试调用 agencyToOwner 和 createRandomAgency 但没有任何效果。

我们很乐意收到任何帮助！谢谢，

Answer 1

我认为你应该尝试这样的事情-:

 var contractAbi= "" //here put your contract abi in json string
 var deployedContract = web3.eth.contract(abi).at("contract address");
 //now you should be able to access contract methods
 deployedContract.agencies.call({from:address}, function(err,data){
 console.log(data);
 });

测试一次。

Answer 2

您可以使用contract.methodName.call()、contract.methodName.sendTransaction()或contract.methodName()方法调用合约函数。最后一个版本根据方法类型简单地委托给前两个版本之一（即，如果它是 constant）。请参阅文档中的 Contract Methods 部分。

参数列表以函数本身的参数（如果有）开头，然后是可选的交易对象，然后是回调。要调用您的 createRandomAgency() 方法，您可以这样做：

const contract = web3.eth.contract(contractAbi);
const contractInstance = contract.at(contractAddress);

const transactionObject = {
  from: fromAccount,
  gas: gasLimit
  gasPrice: gasPriceInWei
};

contractInstance.createRandomAgency.sendTransaction('name', transactionObject, (error, result) => { // do something with error checking/result here });

可以找到交易对象的可用选项列表 here。

要调用您的 public agencies 数组，它看起来像

contractInstance.agencies.call(0, (error, result) => {
  if (!error) {
    console.log(result.name);
    console.log(result.dna);
  }
}); // transaction object not needed

Answer 3

尝试使用回调或承诺。当我想从我的合约方法之一获取 return 值时，以下代码对我有用：

const contract = web3.eth.contract(contractABI);
const contractInstance = contract.at(this.contractAddress);

return new Promise((resolve, reject) => {
  contractInstance.**yourMethod**.call(function (error, result) {
    if (error) {
      console.log(error);
    } else {
      resolve(result);
    }
  });
}) as Promise<number>;

另请查看：https://github.com/ethereum/wiki/wiki/JavaScript-API#using-callbacks

使用 web3 ethereum 调用智能合约方法

calling smart contracts methods using web3 ethereum

javascript

ethereum

web3js

geth