5

I use web3.js and try to take a value of the variable from the smart contract.

My code for it is:

var contract = web3.eth.contract(abi).at(address);

where abi - json array and address - valid working address.

Part of abi json object is

{
      "constant": true,
      "inputs": [],
      "name": "weiRaised",
      "outputs": [
        {
          "name": "",
          "type": "uint256"
        }
      ],
      "payable": false,
      "type": "function"
},

When I use this code:

console.log(contract.abi[0].abi[6].name);

I see "weiRaised" in the console.

But if I use

console.log(contract.abi[0].abi[6].inputs);

I see 'undefined'.

What I am doing wrong? How Can I get the variable from the smart contract, based on abi and web3.js?

4 Answers 4

5

After printing stuff on the console, God let me go to sleep with joy =)

var contract = web3.eth.contract(abi).at(address);
async function getContractPublicVariable() {
    const weiRaised = await contract.methods.weiRaised.call().call();
}

so the idea is contract.methods.VARIABLENAME.call().call();

1
  • Another idea is contract.methods.VARIABLENAME().call();
    – Stiin
    Commented Feb 6, 2022 at 21:08
1

Web3.js will automagically map the ABI functions onto the contract object that you get back from web3.eth.contract(abi).at(address).

This means you can access the value of the variables by doing something like:

let weiRaisedValue = contract.weiRaised.call()

4
  • console.log(contract.weiRaised.call()); - TypeError: contract.weiRaised is undefined
    – Sergei
    Commented Nov 29, 2017 at 19:05
  • 1
    @Sergei Are you using web3 v1.0? In that case it should be contract.methods.weiRaised.call().then(function (res) { console.log(res); }). More info from web3 v1.0 documentation.
    – Ismael
    Commented Nov 30, 2017 at 21:56
  • console.log(web3.version); gives this: Object { api: "0.20.2", node: Getter, getNode: e(), network: Getter, getNetwork: e(), ethereum: Getter, getEthereum: e(), whisper: Getter, getWhisper: e() }
    – Sergei
    Commented Dec 1, 2017 at 23:53
  • your code gives this error to me: TypeError: contract.methods is undefined
    – Sergei
    Commented Dec 1, 2017 at 23:53
0

I'll give an updated answer as of web3.js 1.6.0 (I used moralis as my provider for web3.js)

import Web3 from 'web3';       
const web3Js = new Web3(Moralis.provider);
            var contract = new web3Js.eth.Contract(ContractJSON.abi, ContractAddress);
            const variable = await contract.methods.variableName.call().call();
1
  • 1
    The double call() looks odd, it looks better with contract.methods.variableName().call(), using () after the name and a single .call().
    – Ismael
    Commented Feb 3, 2022 at 13:30
0

2022 WebJs 1.7.3

If anyone struggle with it in 2022, then this is the solution


import Web3 from "web3";

const web3 = new Web3(provider);
const myContract = new web3.eth.Contract(
      jsonInterface,
      address,
    );
this.age = await myContract.methods.getAge().call();

This is the generic form. And It is an async call await myContract.methods.getVariableName().call();

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