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[英]Is there an API to retrieve ERC-721 listings/bids from different marketplaces?
[英]Is there a way to retrieve JSON on Solidity on ERC-721?
我正在练习 ERC_721 合同,想知道是否有办法将 JSON 数据直接存储在合同上,看看我的方法并给出你的想法:
上传到 IPFS 的variation1.json
文件:
{
"attributes": [
{
"trait_type": "Rank",
"value": "1"
}
],
"description": "A simple NFT",
"image": "Qmdasifhw89rv92enfkq128re3",
"name": "NFT#1"
}
然后我会使用一个像下面这样的object
来与将file
引用到urlOfTokenURI
的合同一起使用
[
{
"file": "variation1.json", "urlOfTokenURI": https://gateway.pinata.cloud/ipfs/Qmdasifhw89rv92enfkqeqe23f"
},
{
"file": "variation2.json", "urlOfTokenURI": "https://gateway.pinata.cloud/ipfs/Qmgvfrg34vt4u785ygbmasdsa"
},
...
]
然后获取一个随机数,检索一个随机urlOfTokenURI
并将令牌铸造到所需的地址,从可用令牌列表中排除该令牌:
function mintNFT(address recipient, string memory tokenURI)
public onlyOwner
returns (uint256)
{
_tokenIds.increment();
//retrieve object, get random number and mint with the urlOfTokenURI
//from random number index
uint256 newItemId = _tokenIds.current();
_mint(recipient, newItemId);
_setTokenURI(newItemId, tokenURI);
return newItemId;
}
这个工作缺少什么?
有人可以指导我如何进行或对另一种方法有建议吗? 我有点迷路了。
不明白如何铸造一个随机的 NFT 并立即将其展示给用户。
如果这是一个愚蠢的问题,请提前道歉。 我正在学习,顺便说一句。
感谢帮助!
pragma solidity ^0.8.0;
import "@openzeppelin/contracts/utils/Strings.sol";
...
using Strings for uint256;
using Base64 for bytes;
...
function tokenURI(uint256 id) public view returns (string memory) {
string memory metadata = string(abi.encodePacked(
"{\"name\": \"NFT#",
id.toString(),
"\", \"description\": \"A simple NFT\", \"attributes\":",
"[{\"key\":\"trait_type\",\"value\":\"1\"}]",
"}"
));
return string(abi.encodePacked(
"data:application/json;base64,",
bytes(metadata).base64()
));
}
Base64 库
pragma solidity ^0.8.0;
library Base64 {
string internal constant TABLE = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
function base64(bytes memory data) internal pure returns (string memory) {
if (data.length == 0) return "";
// load the table into memory
string memory table = TABLE;
// multiply by 4/3 rounded up
uint256 encodedLen = 4 * ((data.length + 2) / 3);
// add some extra buffer at the end required for the writing
string memory result = new string(encodedLen + 32);
assembly {
// set the actual output length
mstore(result, encodedLen)
// prepare the lookup table
let tablePtr := add(table, 1)
// input ptr
let dataPtr := data
let endPtr := add(dataPtr, mload(data))
// result ptr, jump over length
let resultPtr := add(result, 32)
// run over the input, 3 bytes at a time
for {} lt(dataPtr, endPtr) {}
{
dataPtr := add(dataPtr, 3)
// read 3 bytes
let input := mload(dataPtr)
// write 4 characters
mstore(resultPtr, shl(248, mload(add(tablePtr, and(shr(18, input), 0x3F)))))
resultPtr := add(resultPtr, 1)
mstore(resultPtr, shl(248, mload(add(tablePtr, and(shr(12, input), 0x3F)))))
resultPtr := add(resultPtr, 1)
mstore(resultPtr, shl(248, mload(add(tablePtr, and(shr( 6, input), 0x3F)))))
resultPtr := add(resultPtr, 1)
mstore(resultPtr, shl(248, mload(add(tablePtr, and( input, 0x3F)))))
resultPtr := add(resultPtr, 1)
}
// padding with '='
switch mod(mload(data), 3)
case 1 { mstore(sub(resultPtr, 2), shl(240, 0x3d3d)) }
case 2 { mstore(sub(resultPtr, 1), shl(248, 0x3d)) }
}
return result;
}
}
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