Cant get the ABI and Interface of solidity code

Question

I am learning solidity following a course. I am completely noob at solidity . I am trying to run my compile.js file using command "node compile.js" .But I am getting same error saying

"SyntaxError: Unexpected token o in JSON at position 1 at JSON.parse ()"

I have tried mulitiple solution to fix this . I did match my solidity version with compiler version . After trying multiple solution ,it seems not to work . Dont know where I am missing the spot .

Here is my compile.js file :

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

const inboxPath = path.resolve(__dirname, 'contracts', 'Inbox.sol');
const source = fs.readFileSync(inboxPath, 'utf8');

const input = {
    language: 'Solidity',
    sources: {
        'Inbox.sol': {
            content: source,
        },
    },
    settings: {
        outputSelection: {
            '*': {
                '*': ['*'],
            },
        },
    },
};

module.exports = JSON.parse(solc.compile(JSON.stringify(input))).contracts['Inbox.sol'].Inbox;

My main contract code :

pragma solidity >=0.4.25 ;

contract inboxx {
    string public message;

    constructor(string memory intialmsg) {
        message = intialmsg;
    }

    function setmessage(string memory newMessage) public {
        message = newMessage;
    }
}

My package.json

{
  "name": "inbox",
  "version": "1.0.0",
  "description": "",
  "main": "index.js",
  "scripts": {
    "test": "mocha"
  },
  "author": "",
  "license": "ISC",
  "dependencies": {
    "ganache-cli": "^6.12.2",
    "mocha": "^10.2.0",
    "openzeppelin-solidity": "^4.6.0",
    "solc": "^0.4.25",
    "web3": "^1.0.0-beta.26"
  }
}

Dont want to quit here . Thanks a lot .

Answer 1

It's related to the version of your solc.

try that instead:

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

const inboxPath = path.resolve(__dirname, 'contracts', 'Inbox.sol');
const source = fs.readFileSync(inboxPath, 'utf8');

const input = {
    'Inbox.sol': source
};
const str = JSON.stringify(input);
const compiled = solc.compile({ sources: input }, 1);
module.exports = {
    abi: compiled.contracts['Inbox.sol:Inbox'].bytecode,
    bytecode: compiled.contracts['Inbox.sol:Inbox'].interface,
}

notice the change in the constructor adding the public keyword

pragma solidity >=0.4.25;

contract Inbox {
    string public message;

    constructor(string memory intialmsg) public{
        message = intialmsg;
    }

    function setmessage(string memory newMessage) public {
        message = newMessage;
    }
}

Check this similar question on SO https://stackoverflow.com/a/53950041/2124936

Answer 2

you should do this instead.

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

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

var input = {
    language: 'Solidity',
    sources: {
        [inboxPath] : {
            content: source
        }
    },
    settings: {
        outputSelection: {
            '*': {
                '*': [ '*' ]
            }
        }
    }
}; 
var output = JSON.parse(solc.compile(JSON.stringify(input)));

module.exports = {
  abi: output.contracts[[inboxPath]]["Inbox"].abi,
  bytecode: output.contracts[[inboxPath]]["Inbox"].evm.bytecode.object,
};

Hope this helps!