I encounter the following error while trying to run a dapp made using React, Truffle & Ganache. I'm also using web3 version 1.7.1. The problem is that the code enters in a catch(error) sequence of a try/catch and then displays what it is intended correctly. Why is this happening and why does the following error appears?
index.js:1 TypeError: Cannot read properties of undefined (reading 'methods')
at HomePage.componentDidMount
What the code should do: Display something like "Address is: 0x0D05b3220E9cC7A90623fc506cEB64Ab885FD6C6"
What the code does: It shows me the prompt "Failed to load web3, accounts, or contract. Check console for details" AND THEN "Address is: 0x0D05b3220E9cC7A90623fc506cEB64Ab885FD6C6"
The code is the following:
import React, { Component } from "react";
import MySmartContract from "../contracts/MySmartContract.json";
import getWeb3 from "../getWeb3";
//Importing components
class HomePage extends Component {
constructor(props) {
super(props);
this.state = {
ContractInstance: undefined,
account: null,
web3: null,
isOwner: false
}
}
componentDidMount = async () => {
// For refreshing the page a single time
// so that web3 and instance is loaded every time
if (!window.location.hash) {
window.location = window.location + '#loaded';
window.location.reload();
}
try {
// Get network provider and web3 instance.
const web3 = await getWeb3();
// Use web3 to get the user's accounts.
const accounts = await web3.eth.getAccounts();
// Get the contract instance.
const networkId = await web3.eth.net.getId();
const deployedNetwork = MySmartContract.networks[networkId];
const instance = new web3.eth.Contract(
MySmartContract.abi,
deployedNetwork && deployedNetwork.address,
);
// Set web3, accounts, and contract to the state, and then proceed with an
// example of interacting with the contract's methods.
this.setState({ ContractInstance: instance, web3: web3, account: accounts[0] });
const owner = await this.state.ContractInstance.methods.getOwnerAddress().call();
if (this.state.account === owner) {
this.setState({ isOwner: true });
}
} catch (error) {
// Catch any errors for any of the above operations.
alert(
`Failed to load web3, accounts, or contract. Check console for details.`,
);
console.error(error);
}
};
render() {
if (!this.state.web3) {
return (
<h1>
Loading Web3, accounts and contract...
</h1>
)
}
return (
<div><h1>Address is: {this.state.account}</h1></div>
)
}
}
export default HomePage;
The content of getWeb3.js is the following:
import Web3 from "web3";
const getWeb3 = () =>
new Promise((resolve, reject) => {
// Wait for loading completion to avoid race conditions with web3 injection timing.
window.addEventListener("load", async () => {
// Modern dapp browsers...
if (window.ethereum) {
const web3 = new Web3(window.ethereum);
try {
// Request account access if needed
await window.ethereum.enable();
// Accounts now exposed
resolve(web3);
} catch (error) {
reject(error);
}
}
// Legacy dapp browsers...
else if (window.web3) {
// Use Mist/MetaMask's provider.
const web3 = window.web3;
console.log("Injected web3 detected.");
resolve(web3);
}
// Fallback to localhost; use dev console port by default...
else {
const provider = new Web3.providers.HttpProvider(
"http://127.0.0.1:8545"
);
const web3 = new Web3(provider);
console.log("No web3 instance injected, using Local web3.");
resolve(web3);
}
});
});
export default getWeb3;
This code seems to be wrong!
You should not try to use state value as soon as you set up.
So you need to call your function in the second line like this:
Injected connector code sample
Usage: