Contract upgrade

Smart Contracts
1

Hi everyone, I've a question about an upgrade that I should apply to an upgradable contract.

I'm following the guidelines and best practices but I'm not sure the change would have any issue.

I would like to:

  1. create a new contract V2 starting from the deployed one

  2. add on this contract a new bool variable

bool private isLocked;

(as last variable in the variables list declaration and without a starting value, since the initialize has been called with the proxy contract deployment)

  1. the first contract deployed has this function
 function _beforeTokenTransfer(address from, address to, uint256 tokenId) internal override (ERC721Upgradeable,ERC721EnumerableUpgradeable) {
    super._beforeTokenTransfer(from, to, tokenId);
  }

I would change it this way, to let the transfer only when isLocked is false or the users are minting

 function _beforeTokenTransfer(address from, address to, uint256 tokenId) internal override (ERC721Upgradeable,ERC721EnumerableUpgradeable) {
        require(!isLocked || from == address(0));
        
        super._beforeTokenTransfer(from, to, tokenId);
    }

and then adding set and get methods to change and retrieve the isLocked variable.

Then I would deploy using the original contract address as in the documentation

async function main () {
  const ContractV2 = await ethers.getContractFactory('ContractV2');
  console.log('Upgrading ContractV2...');
  await upgrades.upgradeProxy(FIRST_CONTRACT_ADDRESS, ContractV2);
  console.log('Contract upgraded');
}

main();

Do you see any issue with these changes?

The new functions, for example the get and set of the isLocked variable, need to follow a specific order in the code (for example at the end of the contract code) or can be placed anywhere, any other aspect to consider?

Thank you