Reading address from environmental variable or hardhat - environment-variables

Question

I'm new at solidity.
I've put here the snippet of code:
import "#chainlink/contracts/src/v0.8/interfaces/AggregatorV3Interface.sol";
contract Example {
AggregatorV3Interface internal priceFeed;
/**
* Network: Goerli
* Aggregator: ETH/USD
* Address: 0xD4a33860578De61DBAbDc8BFdb98FD742fA7028e
*/
constructor() {
priceFeed = AggregatorV3Interface(
0xD4a33860578De61DBAbDc8BFdb98FD742fA7028e
);
owner = msg.sender;
}
}
And if you see, the parameter that I need to send to AggregatorV3Interface is static 0xD4a33860578De61DBAbDc8BFdb98FD742fA7028e.
To me, that doesn't look optimized enough. Because right now, I'm playing with this function for Goerli, but if I were to deploy this contract to Etherium mainnet, I would have to change that address manually. Even if you go to chainlink website, they have it like this. https://docs.chain.link/data-feeds/price-feeds/#solidity
Is there a better way? I would like to have some variable that I would set, and read from it? Or maybe some custom variable setting from hardhat, that I'm using.
priceFeed = AggregatorV3Interface(env.proccess.address); Would be desired, or anything dynamic.

Answer 1

Usual approach is to pass the address to Solidity constructor from a JS (or any other offchain language) script that reads from the environment variable.
.env
AGGREGATOR_ADDRESS=0xD4a33860578De61DBAbDc8BFdb98FD742fA7028e
JS deployer script
require("dotenv").config();
const hre = require("hardhat");
async function main() {
const factory = await hre.ethers.getContractFactory("Example");
// pass constructor arguments to the `deploy()` function
const contract = await factory.deploy(process.env.AGGREGATOR_ADDRESS);
await contract.deployed();
}
main().catch((error) => {
console.error(error);
process.exitCode = 1;
});
Solidity contract
pragma solidity ^0.8;
import "#chainlink/contracts/src/v0.8/interfaces/AggregatorV3Interface.sol";
contract Example {
AggregatorV3Interface internal priceFeed;
constructor(address _aggregator) {
priceFeed = AggregatorV3Interface(_aggregator);
}
}