EIP 4096 has an interesting method of updating your metadata with events, more details here.

https://eips.ethereum.org/EIPS/eip-4906

So lets see how to implement it with an example. First you need to create a file with interface that has this code in it

pragma solidity ^0.8.0;

import "@openzeppelin/contracts/utils/introspection/IERC165.sol";

/// @title EIP-721 Metadata Update Extension
interface IERC4906 is IERC165 {
    /// @dev This event emits when the metadata of a token is changed.
    /// Third-party platforms such as NFT marketplaces can listen to
    /// the event and auto-update the tokens in their apps.
    event MetadataUpdate(uint256 _tokenId);
    /// @dev This event emits when the metadata of a range of tokens is changed.
    /// So that the third-party platforms such as NFT market could
    /// timely update the images and related attributes of the NFTs.
    event BatchMetadataUpdate(uint256 _fromTokenId, uint256 _toTokenId);
}

then we can implement that interface like example below (we also need to use supportsInterface function) and call our event BatchMetadataUpdate in the case of updating of _baseTokenURI as this means all NFTs have new URIs and probably new metadata.

pragma solidity ^0.8.0;

import "@openzeppelin/contracts/token/ERC721/ERC721.sol";
import "./IERC4906.sol";

contract ERC4906 is ERC721, IERC4906 {

string private _baseTokenURI = "some URI"

    constructor(string memory name_, string memory symbol_) ERC721(name_, symbol_) {
    }

    function supportsInterface(
        bytes4 interfaceId
    ) public view virtual override(ERC721A, IERC165) returns (bool) {
        return super.supportsInterface(interfaceId);
    }

    function setBaseURI(string calldata baseURI) external onlyOwner {
        emit BatchMetadataUpdate(1, type(uint256).max);
        _baseTokenURI = baseURI;
    }
}

One of the good things is that this EIP has been supported by Open Sea, which means it should be useful and standardized across industry.

https://docs.opensea.io/docs/metadata-standards#metadata-updates

EIP 4096 has an interesting method of updating your metadata with events, more details here.

https://eips.ethereum.org/EIPS/eip-4906

So lets see how to implement it with an example. First you need to create a file with interface that has this code in it

pragma solidity ^0.8.0;

import "@openzeppelin/contracts/utils/introspection/IERC165.sol";

/// @title EIP-721 Metadata Update Extension
interface IERC4906 is IERC165 {
    /// @dev This event emits when the metadata of a token is changed.
    /// Third-party platforms such as NFT marketplaces can listen to
    /// the event and auto-update the tokens in their apps.
    event MetadataUpdate(uint256 _tokenId);
    /// @dev This event emits when the metadata of a range of tokens is changed.
    /// So that the third-party platforms such as NFT market could
    /// timely update the images and related attributes of the NFTs.
    event BatchMetadataUpdate(uint256 _fromTokenId, uint256 _toTokenId);
}

then we can implement that interface like example below (we also need to use supportsInterface function) and call our event BatchMetadataUpdate in the case of updating of _baseTokenURI as this means all NFTs have new URIs and probably new metadata.

pragma solidity ^0.8.0;

import "@openzeppelin/contracts/token/ERC721/ERC721.sol";
import "./IERC4906.sol";

contract ERC4906 is ERC721, IERC4906 {

string private _baseTokenURI = "some URI"

    constructor(string memory name_, string memory symbol_) ERC721(name_, symbol_) {
    }

    function supportsInterface(
        bytes4 interfaceId
    ) public view virtual override(ERC721A, IERC165) returns (bool) {
        return super.supportsInterface(interfaceId);
    }

    function setBaseURI(string calldata baseURI) external onlyOwner {
        emit BatchMetadataUpdate(1, type(uint256).max);
        _baseTokenURI = baseURI;
    }
}

One of the good things is that this EIP has been supported by Open Sea, which means it should be useful and standardized across industry.

https://docs.opensea.io/docs/metadata-standards#metadata-updates