返回函数中的参数

Question

我有一个从ChainlinkClient继承来向API发送请求的契约，该契约有三个主要功能：

function onTokenTransfer(
    address _sender,
    uint256 _fee,
    bytes calldata _data
) public {
    require(_fee >= fee, "NOT ENOUGH FUNDS");
    bytes memory data = _data[4:];
    uint256 _id = abi.decode(data, (uint256));
    requestVolumeData(_id);
}

function requestVolumeData(uint256 _id) public returns (bytes32 requestId) {
    Chainlink.Request memory req = buildChainlinkRequest(
        jobId,
        address(this),
        this.fulfill.selector
    );

    // do somthing with _id
    req.add(
        "get",
        "https://min-api.cryptocompare.com/data/pricemultifull?fsyms=ETH&tsyms=USD"
    );
    req.add("path", "RAW,ETH,USD,VOLUME24HOUR"); 
    int256 timesAmount = 10 ** 18;
    req.addInt("times", timesAmount);
    return sendChainlinkRequest(req, fee);
}

function fulfill(
    bytes32 _requestId,
    uint256 _volume
) public recordChainlinkFulfillment(_requestId) {
    emit RequestVolume(_requestId, _volume);
    volume = _volume;
}

当用户使用link.transferAndCall使用_id调用我的契约时，onTokenTransfer函数使用相同的_id调用requestVolumeData，该函数向节点发出请求，节点将请求的数据返回给fulfill函数。

My的问题是:如何在实现函数中获得requestVolumeData中使用的_id的值？

我的结构和(id=>struct)映射：

struct Collab {
    address promoter;
    address client;
    string apiUrl;
    uint256 amount;

}

mapping(uint256 => Collab) public collabById;

Answer 1

您可以将_id存储到以下状态变量中：

uint256 id;

function requestVolumeData(uint256 _id) public returns (bytes32 requestId) {



    Collab memory collab;

    // You can set the values that you are having 

    collab.apiUrl = "https://min-api.cryptocompare.com/data/pricemultifull?fsyms=ETH&tsyms=USD";
    
    collab.promoter = msg.sender; // Or any other address that goes here

    collab.client = msg.sender; // Or any other address that goes here

    collab.amount = 0; // Setting this 0 for now, you can leave that too because by-default it's 0 only

    id = _id;

    collabById[id] = collab;

    Chainlink.Request memory req = buildChainlinkRequest(
        jobId,
        address(this),
        this.fulfill.selector
    );

    // do somthing with _id
    req.add(
        "get",
        "https://min-api.cryptocompare.com/data/pricemultifull?fsyms=ETH&tsyms=USD"
    );
    req.add("path", "RAW,ETH,USD,VOLUME24HOUR"); 
    int256 timesAmount = 10 ** 18;
    req.addInt("times", timesAmount);
    return sendChainlinkRequest(req, fee);
}

然后，在fulfill()函数中，可以使用id状态变量访问最新的D4值：

function fulfill(
    bytes32 _requestId,
    uint256 _volume
) public recordChainlinkFulfillment(_requestId) {
    emit RequestVolume(_requestId, _volume);
    volume = _volume;
    // You can set the remaining values of the mapping struct here
    collabById[id].amount = volume;
}