Chainlink request not returning the integer at the followed path

Question

I have a very simple smart contract which creates and sends a Chainlink request to the Kovan Linkpool node using the get>uint256 job. The contract looks like this (API private key removed).

contract OracleChainlink is ChainlinkClient {
    using Chainlink for Chainlink.Request;

    uint256 public H_Index;
    address private Oracle;
    bytes32 private JobId;
    uint256 private Fee = .1 * 10 ** 18; //kovan is .1 link per call

    constructor() public {
        setPublicChainlinkToken();
        Oracle = 0x56dd6586DB0D08c6Ce7B2f2805af28616E082455; //Chainlink linkpool node on Kovan
        JobId = "b6602d14e4734c49a5e1ce19d45a4632";
    }

    function getChainlinkToken() public view returns (address) {
        return chainlinkTokenAddress();
    }

    function RequestH_index() public returns (bytes32 Reqid) {
        Chainlink.Request memory Req = buildChainlinkRequest(JobId, address(this), this.fulfill.selector);

        Req.add("get", "https://serpapi.com/.....");
        Req.add("path", "cited_by.table.1.h_index.all");

        return sendChainlinkRequestTo(Oracle, Req, Fee);        
    }
    
    function fulfill(bytes32 Reqid, uint256 _Hindex) public recordChainlinkFulfillment(Reqid) {
        H_Index = _Hindex;
    }

The Google Scholar Author API https://serpapi.com/google-scholar-author-api returns a pretty large json, seen at the link if you scroll down. The snippet/path I need to follow is shown below (cited_by is at the top level of the json).

  "cited_by": {
    "table": [
      {
        "citations": {
          "all": 23351,
          "since_2016": 13660
        }
      },
      {
        "h_index": {
          "all": 46,
          "since_2016": 37
        }
      },
      {
        "i10_index": {
          "all": 60,
          "since_2016": 53
        }
      }
    ],

When ran, I get logs of Chainlink request events, but the public H_Index value remains 0. Am I missing something in terms of adapters? I have tried all sorts of path formats through the JSON with no luck. I have also tried different nodes and jobs. Is there any way to ensure that the API is even being called? What am I missing?

user_15191896 · Answer

Your JSON Path should look like this:

Req.add("path", "cited_by.table.1.h_index.all");

Looking at the Etherscan activity, it looks like the node you are using may be inactive. Try this node and jobId:

Oracle = 0xc57B33452b4F7BB189bB5AfaE9cc4aBa1f7a4FD8; 
JobId = "d5270d1c311941d0b08bead21fea7747";

These were taken from the Chainlink Official Docs.

To check to see if a node is running or not, check out the oracle address in a block explorer. You can see here that the original node you tried to use hasn't posted a transaction in quite a long time.

If a node is inactive you will need to find a new one or host one yourself. To find more nodes and jobs, you can check market.link or use the one found in the docs as mentioned earlier.

Chainlink request not returning the integer at the followed path

1 Answers