简单的连接代酮与Tokenuri的方法

Question

我正在开普敦大学（University of Cape Town），使用坚固的NFT和Openzeppelin在开普敦大学做一个项目。我已将JSON/PNG的文件夹用于元数据。我现在需要使用代币 + .json在铸造时设置代币正确的URI。以下是简单的合同：

    //SPDX-License-Identifier: MIT
pragma solidity ^0.8;
import "@openzeppelin/contracts/token/ERC721/extensions/ERC721URIStorage.sol";
import "@openzeppelin/contracts/utils/Strings.sol";
contract ImpactCollection is ERC721URIStorage {
    uint256 public tokenCounter;
    constructor () ERC721 ("Impact Tokens", "COLLECTION_TICKER"){
        tokenCounter = 0;
    }
    function concatenate(string memory a,uint256 memory b,string memory c) public pure returns (string memory){
        return string(abi.encodePacked(a,b,c));
    }

    function createCollectible() public returns (uint256) {
        uint256 newItemId = tokenCounter;
        string urinumber = string(abi.encodePacked(newItemId.toString()))
        tokenURI = "https://ipfs.io/ipfs/QmQh54Rb8ZFY33P9bWUzgonRvA7XeChVWaAWG3nMqQ19xW/" + urinumber + ".json";
        _safeMint(msg.sender, newItemId);
        _setTokenURI(newItemId, tokenURI);
        tokenCounter = tokenCounter + 1;
        return newItemId;
    }

}

我上面有文件夹URL，我只需要添加令牌ID，然后添加一个.json即可。我的C＃Brain说：“ ipfsurl” + newitemid.tostring（） +“ .json”;

混音（固体）等效的是什么？

Answer 1

从固体版本 0.8.12 可以使用string.concat（s1，s2）进行连接字符串。
我调整了您的智能合同代码中的一些笔记：

//SPDX-License-Identifier: MIT
pragma solidity ^0.8;

import "@openzeppelin/contracts/token/ERC721/extensions/ERC721URIStorage.sol";
import "@openzeppelin/contracts/utils/Strings.sol";

contract ImpactCollection is ERC721URIStorage {
  uint256 public tokenCounter;
  using Strings for *;
  
  constructor () ERC721 ("Impact Tokens", "COLLECTION_TICKER"){
    tokenCounter = 0;
  }

  function concatenate(string memory a,uint256 b,string memory c) public pure returns (string memory){
    return string(abi.encodePacked(a,b,c));
  }

  function createCollectible() public returns (uint256) {
    uint256 newItemId = tokenCounter;
    // NOTE: Use Strings.toString for convert a uint to string datatype
    string memory urinumber = Strings.toString(newItemId);
    // NOTE: I declared a new variable for contain token URI
    string memory tokenURI = "https://ipfs.io/ipfs/QmQh54Rb8ZFY33P9bWUzgonRvA7XeChVWaAWG3nMqQ19xW/";
    // NOTE: I declare a new variable for contain tokenURI concatenated    
    string memory fullTokenURI = string.concat("https://ipfs.io/ipfs/QmQh54Rb8ZFY33P9bWUzgonRvA7XeChVWaAWG3nMqQ19xW/", urinumber, ".json");
    _safeMint(msg.sender, newItemId);
    _setTokenURI(newItemId, tokenURI);
    tokenCounter = tokenCounter + 1;
    return newItemId;
  }

}

Answer 2

这将起作用！

_setTokenURI(newItemId, string(abi.encodePacked(_uri, '/', newItemId.toString(), '.json')));