CODEWITHSUNDEEP
javascriptnode.jsethereumweb3js
MadTech
MadTech

Reputation: 1498

Node.js - Ethereum Contracts unable to call the functions

I am new to Blockchain development. To learn purpose, started to develop small contracts using ethereum blockchain concept in Node.js

I have install the packages "solc": "^0.4.24" and "web3": "^0.20.7" to build and compile my contracts in Node.

My Grades.sol file:

pragma solidity ^0.4.24;

contract Grades {
    mapping (bytes32 => string) public grades;
    bytes32[] public studentList;

    function Grades(bytes32[] studentNames) public {
        studentList = studentNames;
    }

    function giveGradeToStudent(bytes32 student, string grade) public {
        require(validStudent(student));
        grades[student] = grade;
    }

    function validStudent(bytes32 student) view public returns (bool) {
        for(uint i = 0; i < studentList.length; i++) {
            if (studentList[i] == student) {
                return true;
            }
        }
        return false;
    }

    function getGradeForStudent(bytes32 student) view public returns (string) {
        require(validStudent(student));
        return grades[student];
    }
}

And my compile.js file.

const path = require('path');
const fs = require('fs');
const solc = require('solc');
const Web3 = require('web3');


const helloPath = path.resolve(__dirname,'contracts','Grades.sol');
const source = fs.readFileSync(helloPath,'UTF-8');

compiledCode = solc.compile(source);

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

abiDefinition = JSON.parse(compiledCode.contracts[':Grades'].interface);

GradesContract = web3.eth.contract(abiDefinition);

byteCode = compiledCode.contracts[':Grades'].bytecode

deployedContract = GradesContract.new(['John','James'],{data: byteCode, from: web3.eth.accounts[0], gas: 4700000}); 

deployedContract.giveGradeToStudent('John', 'A+', {from: web3.eth.accounts[0]});

I tried to compile and run i am getting the exception 

TypeError: deployedContract.giveGradeToStudent is not a function

In deployedContract, I am able to see the methods. Can anyone help me on this?

Note: I have installed "ganache-cli": "^6.1.8" for adding the Transactions and running sepratly. I am able to see the transactions in ganache.

Upvotes: 0

Views: 124

Answers (1)

user94559
user94559

Reputation: 60153

I believe the issue is here:

deployedContract = GradesContract.new(['John','James'],{data: byteCode, from: web3.eth.accounts[0], gas: 4700000});

.new() here won't return the deployed contract instance. (I'm not sure it returns anything?) You need a callback, like so:

deployedContract = GradesContract.new(
  ['John', 'James'],
  {data: byteCode, from: web3.eth.accounts[0], gas: 4700000},
  function (err, instance) {
    if (instance.address) {
      instance.giveGradeToStudent(...);
    }
  }
);

Upvotes: 1

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