Metamask Issues: Cannot Call Methods from Contract in React JS

As a developer working with a React.js application using Solidity, Ganache, Truffle, and React, you may encounter an issue where you cannot call methods from the contract. This issue is quite common when using Metamask as a wallet provider for Ethereum smart contracts.

Background

In a typical React.js application, you can interact with a smart contract through its ABI (Application Binary Interface) or its web3 library. However, when using Metamask as a wallet provider, things get more complicated. Metamask is an Ethereum-compatible wallet that allows users to securely store and manage private keys.

Issue: Cannot call contract methods

When you try to call a method from your contract using Web3 or another library, you may encounter the following error:

“Type error”: method ‘call’ cannot be called on contract

This error occurs when Metamask tries to call a method that is not in the contract’s ABI.

Troubleshooting steps

To resolve this issue, follow these steps:

Step 1: Examine the contract ABI

Open your smart contract and check its ABI using Truffle Explorer or Ganache console. This helps identify methods that are not in the contract’s ABI.

Step 2: Update the contract’s ABI

If the contract’s ABI method is missing, update it to display the correct function name. You can do this by updating your contract code with the following changes:

• In Solidity, change the “function” declarations to “function”.

• Remove all references to the method from the contract’s repository or event functions.

Update example

contract MyContract {
byte memory myData = bytes(32);
function myFunction() public pure returns (string) {
return "Hello World";
}
}

Step 3: Use Web3 to call methods

Once you’ve updated the contract’s ABI, you can use Web3 to call contract methods using libraries like “web3.js”. Here’s an example:

import * as web3 from 'web3';
const web3 = new web3.Web3(ganache);
const myContract = ganache.getContractAccount('myContractAddress');
myContract.myFunction().then((result) => {
console.log(result);
});

Step 4: Use a library to handle contract interactions

If you’re using React, you can use libraries like web3-react or ethers.js to handle contract interactions. These libraries provide a simpler experience and automatically update the contract ABI for you.

Example: web3-react

import * as web3 from 'web3-react';
const Web3 = () => {
const web3 = new web3.Web3(window.ethereum);
const myContract = web3.getContractAccount('myContractAddress');
back (

{myContract.myFunction()}
);
};

If you follow these steps and use libraries like web3-react or ethers.js, you should be able to call methods from a contract in your React.js application as a provider for the Metamask wallet.

Ethereum Open Source Asic