如何刻录erc721令牌？

Question

我正在尝试烧掉erc721令牌。我继承了ERC721Burnable合同，但是事务得到了failed.While调试--我发现在ERC721URIStorage合同中，它返回到：

if (bytes(_tokenURIs[tokenId]).length != 0) {
    delete _tokenURIs[tokenId];
}

.Also，我希望契约的所有者能够修改元数据。这是我的合同：

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.4;

import "@openzeppelin/contracts/token/ERC721/ERC721.sol";
import "@openzeppelin/contracts/token/ERC721/extensions/ERC721Enumerable.sol";
import "@openzeppelin/contracts/token/ERC721/extensions/ERC721URIStorage.sol";
import "@openzeppelin/contracts/token/ERC721/extensions/ERC721Burnable.sol";
import "@openzeppelin/contracts/access/Ownable.sol";
import "@openzeppelin/contracts/utils/Counters.sol";

contract MyNFT is ERC721, ERC721Enumerable, ERC721URIStorage, ERC721Burnable, Ownable {
    using Counters for Counters.Counter;

    Counters.Counter private _tokenIdCounter;
    uint MAX_SUPPLY=1;

    constructor() ERC721("MyNFT", "MNFT") {}

    function safeMint(address to, string memory uri) public onlyOwner {
        require(totalSupply() < MAX_SUPPLY, "Can be minted only one time.");
        uint256 tokenId = _tokenIdCounter.current();
        _tokenIdCounter.increment();
        _safeMint(to, tokenId);
        _setTokenURI(tokenId, uri);
    }

    // The following functions are overrides required by Solidity.

    function _beforeTokenTransfer(address from, address to, uint256 tokenId)
        internal
        override(ERC721, ERC721Enumerable)
    {
        super._beforeTokenTransfer(from, to, tokenId);
    }

    function _burn(uint256 tokenId) internal override(ERC721, ERC721URIStorage) {
        super._burn(tokenId);
    }

    function tokenURI(uint256 tokenId)
        public
        view
        override(ERC721, ERC721URIStorage)
        returns (string memory)
    {
        return super.tokenURI(tokenId);
    }

    function supportsInterface(bytes4 interfaceId)
        public
        view
        override(ERC721, ERC721Enumerable)
        returns (bool)
    {
        return super.supportsInterface(interfaceId);
    }
}

Answer 1

如果某个特定tokenId的令牌不是尚未铸造，就是已经铸造和烧掉了，希望这会有所帮助！

Answer 2

众所周知，EVM在tx恢复原因方面缺乏明确性。_burn()和burn()函数的源代码显示了可能的错误可能导致还原tx的多个地方：

    function _burn(uint256 tokenId) internal virtual {
        address owner = ERC721.ownerOf(tokenId);

        _beforeTokenTransfer(owner, address(0), tokenId);

        // Update ownership in case tokenId was transferred by `_beforeTokenTransfer` hook
        owner = ERC721.ownerOf(tokenId);

        // Clear approvals
        delete _tokenApprovals[tokenId];

        unchecked {
            // Cannot overflow, as that would require more tokens to be burned/transferred
            // out than the owner initially received through minting and transferring in.
            _balances[owner] -= 1;
        }
        delete _owners[tokenId];

        emit Transfer(owner, address(0), tokenId);

        _afterTokenTransfer(owner, address(0), tokenId);
    }

function burn(uint256 tokenId) public virtual {
    //solhint-disable-next-line max-line-length
    require(_isApprovedOrOwner(_msgSender(), tokenId), "ERC721: caller is not token owner or approved");
    _burn(tokenId);
}

如果您确信您的代码在以下位置失败：

if (bytes(_tokenURIs[tokenId]).length != 0) {
    delete _tokenURIs[tokenId];
}

您需要在这个代码块执行阶段进行双重检查，这个实体_tokenURIs[tokenId]仍然存在。

此外，我建议使用“硬帽子”，因为它在tx、恢复的原因响应中更清晰，并在您的合同上实现了_burn()函数，以便为调试目的向控制台添加日志，这可以更好地帮助我找出问题的原因。