Fetching a string-value via an Oracle

readme.md

Testnet oracle & job details

Kovan

Oracle Address/ID: 0x17A8182DBF79427801573A3D75d42eB9B1215DEF
Get > Bytes32 jobId: 1349eaee74fd40cba66f1a466eee80a7

Rinkeby

Oracle Address/ID: 0xD0691a51e3C6c562691D3C44C2944Bd9D368Ec1f
Get > Bytes32 jobId: cc01528b2baf400e9386cf84b6daa9f2

CallingContract.sol

contract MyContract {

  string public lastMarket;

  function requestEthereumLastMarket(address _oracle, string memory _jobId)
    public
    onlyOwner
  {
    Chainlink.Request memory req = buildChainlinkRequest(stringToBytes32(_jobId), address(this), this.fulfillEthereumLastMarket.selector);
    req.add("get", "https://min-api.cryptocompare.com/data/pricemultifull?fsyms=ETH&tsyms=USD");
    req.add("path", "RAW,ETH,USD,LASTMARKET"); // Chainlink nodes 1.0.0 and later support this format
    sendChainlinkRequestTo(_oracle, req, ORACLE_PAYMENT);
  }
  
  function fulfillEthereumLastMarket(bytes32 _requestId, bytes32 _market)
    public
    recordChainlinkFulfillment(_requestId)
  {
    emit RequestEthereumLastMarket(_requestId, _market);

    // _market will contain a bytes32-encoded string value
    // e.g. the value of "Coinbase" will be encoded as
    // 0x436f696e62617365000000000000000000000000000000000000000000000000

    lastMarket = string(abi.encodePacked(_market));

  }
  
}

Get > Bytes32 Job Spec.toml

type = "directrequest"
schemaVersion = 1
name = "Get > Bytes32 v14"
externalJobID = "1349eaee-74fd-40cb-a66f-1a466eee80a7"
maxTaskDuration = "0s"
contractAddress = "0x17A8182DBF79427801573A3D75d42eB9B1215DEF"
minIncomingConfirmations = 0
observationSource = """
    decode_log   [type="ethabidecodelog"
                  abi="OracleRequest(bytes32 indexed specId, address requester, bytes32 requestId, uint256 payment, address callbackAddr, bytes4 callbackFunctionId, uint256 cancelExpiration, uint256 dataVersion, bytes data)"
                  data="$(jobRun.logData)"
                  topics="$(jobRun.logTopics)"]

    decode_cbor  [type="cborparse" data="$(decode_log.data)"]
    fetch        [type="http" method=GET url="$(decode_cbor.get)"]
    parse        [type="jsonparse" path="$(decode_cbor.path)" data="$(fetch)"]
    encode_data  [type="ethabiencode" abi="(bytes8 value)" data="{ \\"value\\": $(parse) }"]
    encode_tx    [type="ethabiencode"
                  abi="fulfillOracleRequest(bytes32 requestId, uint256 payment, address callbackAddress, bytes4 callbackFunctionId, uint256 expiration, bytes32 data)"
                  data="{\\"requestId\\": $(decode_log.requestId), \\"payment\\": $(decode_log.payment), \\"callbackAddress\\": $(decode_log.callbackAddr), \\"callbackFunctionId\\": $(decode_log.callbackFunctionId), \\"expiration\\": $(decode_log.cancelExpiration), \\"data\\": $(encode_data)}"
                  ]
    submit_tx    [type="ethtx" to="0x17A8182DBF79427801573A3D75d42eB9B1215DEF" data="$(encode_tx)"]

    decode_log -> decode_cbor -> fetch -> parse -> encode_data -> encode_tx -> submit_tx
"""