使用 web3js 呼叫“視圖”函式

— 大量編輯 —

Solidity 合約：

pragma solidity ^0.4.24;


contract PatientRecords {

struct Patient {
   string ID;
   string weight;
   string height;
   string diseasehistory;
   string vaccinecard;
   string name;
   address registrantAddress;
}

uint ID;

constructor() public {
   ID = 0;

}


Patient[] public patients;
mapping(string => uint) names;

function register(string _id, string _weight, string _height, string _diseasehistory, string _vaccinecard, string _name) public returns (bool, uint){
   for (uint i = 0; i < patients.length; i++) {
        require (stringsEqual(patients[i].ID, _id) == false); 
   }
 names[_name] = ID;
 ID++;
  patients.push(Patient(_id, _weight, _height, _diseasehistory, _vaccinecard, _name,  msg.sender));
  return (true, ID);
}

function verifyByName(string _name) public view returns(string, string, string, string, string, string) {
  uint n;
  n = names[_name];
  return (
       patients[n].name,
       patients[n].ID,
       patients[n].weight,
       patients[n].height,
       patients[n].diseasehistory,
       patients[n].vaccinecard);
}

function stringsEqual(string storage _a, string memory _b) internal pure returns(bool) {
   bytes storage a = bytes(_a);
   bytes memory b = bytes(_b);
   if (keccak256(a) != keccak256(b)) {
       return false;
   }
   return true;
}

}

HTML輸入欄&按鈕程式碼：

<input id="name" type="text">
<button id="button2">Search</button>

我需要的：

1. 使用者在 HTML 上輸入一個值
2. 使用者點擊按鈕
3. 值作為參數傳遞給合約的“視圖”函式
4. HTML 顯示合約返回的任何內容

那麼，使用上面的程式碼，我怎樣才能達到這 4 點呢？

謝謝你。

如果您理解本教程並遵循所有說明，那就太好了。他們使用 MetaMask，這意味著他們使用 web3js 0.x 版本。

var web3 = window.web3;
if (typeof web3 !== 'undefined') {
 // Use Mist/MetaMask's provider.
 web3 = new Web3(web3.currentProvider)
} else {
 // Fallback to localhost if no web3 injection. We've configured this to
 // use the development console's port by default.
 web3 = new Web3(new Web3.providers.HttpProvider('http://127.0.0.1:9545'));
}

const patientrecordsContract = web3.eth.contract(<ABI>);
const instance = patientrecordsContract.at('0xdbdc2f9850e93fbdd894a5916010605f463b66d1')
instance.verifyByName("q", (error, data) => {
 console.log(error, data);
});

引用自：https://ethereum.stackexchange.com/questions/60117