How to change storage safely of upgradeable contract

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, ,
1

Hi, I was writing an upgradeable contract using openzeppelin's upgrades contract.

Is it possible to change the storage of the upgrade implementation ?

I was thinking of adding new variables to the end. Will it work?

For example if my contract is something like this

contract TestContract is Initializable {
    address public DAO;

    address public Treasury;

    struct Protocol{
        mapping(address => bool) protocolAssets;
        address depositor;
        uint256[] whitelistGroup;
        address admin;
 
    }


    mapping(address => bool) assets;

    function something() public {
    dao = address(0)
}

Will adding a new variable after the assets mapping, for the new upgrade implementation, work?

2

yes, you should be fine if you only add new variables after the last variable of the old version, as described here https://docs.openzeppelin.com/upgrades-plugins/1.x/proxies#storage-collisions-between-implementation-versions and here https://docs.openzeppelin.com/upgrades-plugins/1.x/writing-upgradeable#modifying-your-contracts

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3

some patterns you might also want to look into are the gap variable and diamond storage: The better way to define the variable __gap in the proxy contract

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4

Yes, this is the way to go.

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