ERC-721 上的外部變數

我對智能合約相當陌生，我想知道如何將外部變數傳遞給我的ERC-721合約。例如，我希望以下函式返回一個外部變數：

function _baseURI() override internal view virtual returns (string memory) {
   return my_variable_here;
}

我正在remix.ethereum.org編譯契約，我想在左側鍵入變數，如下所示：

上圖只是一個範例，因為我要傳遞的真正變數是一個 IPFS url，我不想對其進行硬編碼。

---

接觸

pragma solidity ^0.8.16;

import "erc721a/contracts/ERC721A.sol";

contract test123 is ERC721A {
   constructor() ERC721A("test123", "test123") {}

   function mint(uint256 quantity) external payable {
       // `_mint`'s second argument now takes in a `quantity`, not a `tokenId`.
       _mint(msg.sender, quantity);
   }

   function _baseURI() override internal view virtual returns (string memory) {
       return "ipfs://bafybeigshu4xqcajjkbqw24cea6shz2vh7dibp7yowjmxo4yg32aoma123/";
   }
}

你有幾個選擇：

1. 您可以在建構子中傳遞它並將其設置為狀態變數：

contract test123 is ERC721A {

   string public baseUri;

   constructor(string memory _baseUri) ERC721A("test123", "test123") {
       baseUri = _baseUri;
   }

   function mint(uint256 quantity) external payable {
       // `_mint`'s second argument now takes in a `quantity`, not a `tokenId`.
       _mint(msg.sender, quantity);
   }

   function _baseURI() override internal view virtual returns (string memory) {
       return baseUri;
   }

}

2. 您可以創建一個 setter 方法來動態更改它，只有所有者可以呼叫：

import "erc721a/contracts/ERC721A.sol";

contract test123 is ERC721A {

   string public baseUri;
   address public owner;

   constructor() ERC721A("test123", "test123") {
       owner = msg.sender;
   }

   function mint(uint256 quantity) external payable {
       // `_mint`'s second argument now takes in a `quantity`, not a `tokenId`.
       _mint(msg.sender, quantity);
   }

   function _baseURI() override internal view virtual returns (string memory) {
       return baseUri;
   }

   function getBaseURI(string memory _baseUri) external onlyOwner {
       baseUri = _baseUri;
   }

   modifier onlyOwner() {
       require(owner == msg.sender, "Not owner");
       _;
   }

}

3. 或者兩者兼而有之，在建構子中設置它並且還能夠動態更改它：

contract test123 is ERC721A {

   string public baseUri;
   address public owner;

   constructor(string memory _baseUri) ERC721A("test123", "test123") {
       baseUri = _baseUri;
       owner = msg.sender;
   }

   function mint(uint256 quantity) external payable {
       // `_mint`'s second argument now takes in a `quantity`, not a `tokenId`.
       _mint(msg.sender, quantity);
   }

   function _baseURI() override internal view virtual returns (string memory) {
       return baseUri;
   }

   function getBaseURI(string memory _baseUri) external onlyOwner {
       baseUri = _baseUri;
   }

   modifier onlyOwner() {
       require(owner == msg.sender, "Not owner");
       _;
   }

}

從_baseURI函式中，您只需返回此baseUri狀態變數。

引用自：https://ethereum.stackexchange.com/questions/134527