等待合同接收ERC721令牌

Question

我试图为用户之间的NFT创建一个明智的契约。每当用户尝试创建抽奖时，他们都需要指定tokenContract (这是NFT的契约地址)和tokenId (将是相应的id )。我使用一个简单的造币合同来模拟向合同发送令牌。但是，当发送抽奖合同的造币券，并有onERC721Received设置，State不会被更改为1。

根据以太扫描的说法，抽奖合同确实成功地接收了ERC721令牌。

抽奖合同的有关部分：

import "@openzeppelin/contracts/token/ERC721/ERC721.sol";
import "@openzeppelin/contracts/token/ERC721/IERC721Receiver.sol";

...

contract Raffle is VRFConsumerBase, IERC721Receiver {

    enum State {
        Pending,
        Active,
        Calculating,
        Finished
    }

    State public state;

    ...
    ...

    function onERC721Received(address, address, uint256, bytes calldata) external override returns (bytes4) {
        state = State.Active;
        
        return IERC721Receiver.onERC721Received.selector;
    }

铸币合同：

pragma solidity ^0.8.0;

import "@openzeppelin/contracts/token/ERC721/extensions/ERC721URIStorage.sol";
import "@openzeppelin/contracts/utils/Counters.sol";
import "@openzeppelin/contracts/access/Ownable.sol";
 
contract TestToken is ERC721URIStorage, Ownable {
     using Counters for Counters.Counter;
    Counters.Counter private _tokenIds;

    constructor() ERC721("TestToken", "TST") {}
 
    function mintNFT(address recipient)
        public onlyOwner
        returns (uint256)
    {
        _tokenIds.increment();
 
        uint256 newItemId = _tokenIds.current();
        _mint(recipient, newItemId);
 
        return newItemId;
    }
}

Answer 1

为什么不内部化传输过程并使用标准的ERC721库呢？

function transferNFT(address _nft, uint256 _tokenId) public {
    // Check if sender approved contract to use _tokenId
    require(ERC721(_nft).getApproved(_tokenId) == address(this) ||
        isApprovedForAll(tx.origin, address(this)) == true,
        "Not approved to transfer NFT");
    // Check if sender is the owner of _tokenId
    require(ERC721(_nft).ownerOf(_tokenId) == tx.origin, "Not owner of token");

    // Process transaction
    ERC721(_nft).transferFrom(tx.origin, address(this), _tokenId);

    // Check that transaction was successful
    require(ERC721(_nft).ownerOf(_tokenId) == address(this), "Transfer failed");
}

您可以使用标准的ERC721 ownerOf函数来验证调用传递函数后是否完成了传输。