1

我一直在尝试学习如何使用 Chainlink 发出 GET 请求。

我正在观看本教程：https ://www.youtube.com/watch?v= ay4rXZhAefs，我使用了他们在视频中使用的完全相同的代码，我也使用了 Remix 遵循相同的步骤（我有我的元掩码（Kovan ）以足够的 ETH 和 LINK 开放，我还用足够的 LINK 为我的合同提供资金）。但是，在我调用 requestVolumeData() 之后，音量变量不会更新并保持为 0。

我曾尝试使用不同的网络和预言机/作业，但我似乎一遍又一遍地遇到同样的问题。任何帮助，将不胜感激。

pragma solidity ^0.6.0;

import "@chainlink/contracts/src/v0.6/ChainlinkClient.sol";

/**
 * THIS IS AN EXAMPLE CONTRACT WHICH USES HARDCODED VALUES FOR CLARITY.
 * PLEASE DO NOT USE THIS CODE IN PRODUCTION.
 */
contract APIConsumer is ChainlinkClient {
    using Chainlink for Chainlink.Request;
  
    uint256 public volume;
    
    address private oracle;
    bytes32 private jobId;
    uint256 private fee;
    
    /**
     * Network: Kovan
     * Oracle: 0x2f90A6D021db21e1B2A077c5a37B3C7E75D15b7e
     * Job ID: 29fa9aa13bf1468788b7cc4a500a45b8
     * Fee: 0.1 LINK
     */
    constructor() public {
        setPublicChainlinkToken();
        oracle = 0x2f90A6D021db21e1B2A077c5a37B3C7E75D15b7e;
        jobId = "29fa9aa13bf1468788b7cc4a500a45b8";
        fee = 0.1 * 10 ** 18; // (Varies by network and job)
    }
    
    /**
     * Create a Chainlink request to retrieve API response, find the target
     * data, then multiply by 1000000000000000000 (to remove decimal places from data).
     */
    function requestVolumeData() public returns (bytes32 requestId) 
    {
        Chainlink.Request memory request = buildChainlinkRequest(jobId, address(this), this.fulfill.selector);
        
        // Set the URL to perform the GET request on
        request.add("get", "https://min-api.cryptocompare.com/data/pricemultifull?fsyms=ETH&tsyms=USD");
        
        // Set the path to find the desired data in the API response, where the response format is:
        // {"RAW":
        //   {"ETH":
        //    {"USD":
        //     {
        //      "VOLUME24HOUR": xxx.xxx,
        //     }
        //    }
        //   }
        //  }
        request.add("path", "RAW.ETH.USD.VOLUME24HOUR");
        
        // Multiply the result by 1000000000000000000 to remove decimals
        int timesAmount = 10**18;
        request.addInt("times", timesAmount);
        
        // Sends the request
        return sendChainlinkRequestTo(oracle, request, fee);
    }
    
    /**
     * Receive the response in the form of uint256
     */ 
    function fulfill(bytes32 _requestId, uint256 _volume) public recordChainlinkFulfillment(_requestId)
    {
        volume = _volume;
    }
 
    // function withdrawLink() external {} - Implement a withdraw function to avoid locking your LINK in the contract
}
4

1 回答 1

1

您是否给了一些时间让节点获取请求？执行此示例时，通常必须多次单击 requestVolumeData() 按钮，等待节点完成请求。一般不到两分钟。

这是该示例合同的另一个更新版本。这几乎是一样的。

// SPDX-License-Identifier: MIT

pragma solidity ^0.6.6;

import "@chainlink/contracts/src/v0.6/ChainlinkClient.sol";

contract APIConsumer is ChainlinkClient {


uint256 public volume;

address private oracle;
bytes32 private jobId;
uint256 private fee;

/**
 * Network: Kovan
 * Oracle: 0x2f90A6D021db21e1B2A077c5a37B3C7E75D15b7e
 * Job ID: 29fa9aa13bf1468788b7cc4a500a45b8
 * Fee: 0.1 LINK
 */
constructor(address _oracle, string memory _jobId, uint256 _fee, address _link) public {
    if (_link == address(0)) {
        setPublicChainlinkToken();
    } else {
        setChainlinkToken(_link);
    }
    // oracle = 0x2f90A6D021db21e1B2A077c5a37B3C7E75D15b7e;
    // jobId = "29fa9aa13bf1468788b7cc4a500a45b8";
    // fee = 0.1 * 10 ** 18; // 0.1 LINK
    oracle = _oracle;
    jobId = stringToBytes32(_jobId);
    fee = _fee;
}

/**
 * Create a Chainlink request to retrieve API response, find the target
 * data, then multiply by 1000000000000000000 (to remove decimal places from data).
 */
function requestVolumeData() public returns (bytes32 requestId) 
{
    Chainlink.Request memory request = buildChainlinkRequest(jobId, address(this), this.fulfill.selector);
    
    // Set the URL to perform the GET request on
    request.add("get", "https://min-api.cryptocompare.com/data/pricemultifull?fsyms=ETH&tsyms=USD");
    
    // Set the path to find the desired data in the API response, where the response format is:
    // {"RAW":
    //   {"ETH":
    //    {"USD":
    //     {
    //      "VOLUME24HOUR": xxx.xxx,
    //     }
    //    }
    //   }
    //  }
    request.add("path", "RAW.ETH.USD.VOLUME24HOUR");
    
    // Multiply the result by 1000000000000000000 to remove decimals
    int timesAmount = 10**18;
    request.addInt("times", timesAmount);
    
    // Sends the request
    return sendChainlinkRequestTo(oracle, request, fee);
}

/**
 * Receive the response in the form of uint256
 */ 
function fulfill(bytes32 _requestId, uint256 _volume) public recordChainlinkFulfillment(_requestId)
{
    volume = _volume;
}

function stringToBytes32(string memory source) public pure returns (bytes32 result) {
    bytes memory tempEmptyStringTest = bytes(source);
    if (tempEmptyStringTest.length == 0) {
        return 0x0;
    }

    assembly {
        result := mload(add(source, 32))
    }
}
}
于 2021-08-15T05:52:45.840 回答