Solidity - Check balance of a user address using openzeppelin - blockchain

Question

I'm using Truffle and upgradable Openzeppelin contracts. I have two contracts.
Token.sol:
// SPDX-License-Identifier: MIT
pragma solidity ^0.8.2;
import "#openzeppelin/contracts-upgradeable/token/ERC20/ERC20Upgradeable.sol";
import "#openzeppelin/contracts-upgradeable/proxy/utils/Initializable.sol";
contract MyToken is Initializable, ERC20Upgradeable {
/// #custom:oz-upgrades-unsafe-allow constructor
constructor() initializer {}
function initialize() initializer public {
__ERC20_init("MyToken", "MTK");
_mint(msg.sender, 10000000 * 10 ** decimals());
}
}
AnotherContract.sol:
pragma solidity ^0.8.2;
import "./IAnotherContract.sol";
contract AnotherContract is IAnotherContract {
function doSomethingIfBalanceIsEnough()
external
returns (string memory)
{
// ...
}
}
How do I check how many MTK tokens a user has? I need to check it in doSomethingIfBalanceIsEnough function.

Answer 1

The token contract implements a balanceOf() function that returns token balance of an address.
You can make an external call from AnotherContract to MyToken address, invoking its balanceOf() function, passing it the user's address.
pragma solidity ^0.8.2;
import "./IAnotherContract.sol";
interface IERC20 {
function balanceOf(address) external view returns (uint256);
}
contract AnotherContract is IAnotherContract {
function doSomethingIfBalanceIsEnough()
external
returns (string memory)
{
uint256 userBalance = IERC20(myTokenAddress).balanceOf(msg.sender);
if (userBalance > 0) {
// ...
}
}
}