How to use Chainlink AggregatorV3Interface with UUPSUpgradeable? - chainlink

Question

Will Chainlink's AggregatorV3Interface.sol work with an OpenZeppelin upgradable contract?
Do I place the
"priceFeed =
AggregatorV3Interface(0x9326BFA02ADD2366b30bacB125260Af641031331);"
inside the "initializer{}"?
I would like the address "0x9326BFA02ADD2366b30bacB125260Af641031331"
to be upgradable in the next version of the smart contract.
Is there already a way to do so?
Thank you!
Motivation & Justification
I hope that it makes sense to want to "getLatestPrice()" within the smart contract of a new token.
Before deployment, there is no way of knowing the new token's address.
I would like to change the address using the OpenZeppelin upgradable contract under the UUPS proxy pattern.
Is there any example online to update
priceFeed =
AggregatorV3Interface(0x9326BFA02ADD2366b30bacB125260Af641031331); //
Kovan Testnet
on version 2 of the smart contract?
Thank you!
Important Links:
OpenZeppelin Contracts Wizard
get-the-latest-price using Chainlink's AggregatorV3Interface
Deploying an UUPS Upgradable Contract
I have no idea how to work on version 2 of an UUPS Upgradable Contract.
This is where I got stuck using Chainlink's AggregatorV3Interface.sol with every feature selected on OpenZeppelin Contracts Wizard:
// SPDX-License-Identifier: MIT pragma solidity ^0.8.4;
import
"./#openzeppelin/contracts-upgradeable/token/ERC20/ERC20Upgradeable.sol";
import "./#openzeppelin/contracts-
upgradeable/token/ERC20/extensions/ERC20BurnableUpgradeable.sol";
import "./#openzeppelin/contracts-
upgradeable/token/ERC20/extensions/ERC20SnapshotUpgradeable.sol";
import
"./#openzeppelin/contracts-upgradeable/access/OwnableUpgradeable.sol";
import
"./#openzeppelin/contracts-upgradeable/security/PausableUpgradeable.sol";
import
"./#openzeppelin/contracts-upgradeable/token/ERC20/extensions/draft-
ERC20PermitUpgradeable.sol"; import "./#openzeppelin/contracts-
upgradeable/token/ERC20/extensions/ERC20VotesUpgradeable.sol"; import
"./#openzeppelin/contracts-
upgradeable/token/ERC20/extensions/ERC20FlashMintUpgradeable.sol";
import
"./#openzeppelin/contracts-upgradeable/proxy/utils/Initializable.sol";
import
"./#openzeppelin/contracts-upgradeable/proxy/utils/UUPSUpgradeable.sol";
import
"#chainlink/contracts/src/v0.8/interfaces/AggregatorV3Interface.sol";
contract UpToken is Initializable, ERC20Upgradeable,
ERC20BurnableUpgradeable, ERC20SnapshotUpgradeable,
OwnableUpgradeable, PausableUpgradeable, ERC20PermitUpgradeable,
ERC20VotesUpgradeable, ERC20FlashMintUpgradeable, UUPSUpgradeable {
/// #custom:oz-upgrades-unsafe-allow constructor AggregatorV3Interface
internal priceFeed; constructor() initializer {
priceFeed = AggregatorV3Interface(0x9326BFA02ADD2366b30bacB125260Af641031331); //
Kovan Testnet }
function initialize() initializer public {
__ERC20_init("UpToken", "UPT");
__ERC20Burnable_init();
__ERC20Snapshot_init();
__Ownable_init();
__Pausable_init();
__ERC20Permit_init("UpToken");
__ERC20FlashMint_init();
__UUPSUpgradeable_init(); }
function snapshot() public onlyOwner {
_snapshot(); }
function pause() public onlyOwner {
_pause(); }
function unpause() public onlyOwner {
_unpause(); }
function mint(address to, uint256 amount) public onlyOwner {
_mint(to, amount); }
function _beforeTokenTransfer(address from, address to, uint256
amount)
internal
whenNotPaused
override(ERC20Upgradeable, ERC20SnapshotUpgradeable) {
super._beforeTokenTransfer(from, to, amount); }
function _authorizeUpgrade(address newImplementation)
internal
onlyOwner
override {}
// The following functions are overrides required by Solidity.
function _afterTokenTransfer(address from, address to, uint256 amount)
internal
override(ERC20Upgradeable, ERC20VotesUpgradeable) {
super._afterTokenTransfer(from, to, amount); }
function _mint(address to, uint256 amount)
internal
override(ERC20Upgradeable, ERC20VotesUpgradeable) {
super._mint(to, amount); }
function _burn(address account, uint256 amount)
internal
override(ERC20Upgradeable, ERC20VotesUpgradeable) {
super._burn(account, amount); }
function getLatestPrice() public view returns (int) {
(
/uint80 roundID/,
int price,
/uint startedAt/,
/uint timeStamp/,
/uint80 answeredInRound/
) = priceFeed.latestRoundData();
return price; }
}

Answer 1

Recommend you use hardhat with the upgrades plugin (https://docs.openzeppelin.com/contracts/4.x/upgradeable) to achieve this. When you deploy it the first time using hardhat, it will deploy the proxy, the implementation contract (i.e. your token contract) and an admin contract.
See 20:23 onwards in this video: https://www.youtube.com/watch?v=bdXJmWajZRY&t=15s . In fact maybe watch that entire video to get a sense of how to use hardhat with OZ upgradeable contracts.
Then when you get your token contract address, update the token contract as V2, add the contract address as a state variable and (optionally) add a setter function that gives you the ability to update that state variable in future, and deploy V2. You can see how to deploy V2 in that same video I linked above, at [24:30] or so.