async function queryByString()

in ngo-chaincode/src/ngo.js [53:133]
58 lines of code
14 McCabe index (conditional complexity)

async function queryByString(stub, queryString) {
  console.log('============= START : queryByString ===========');
  console.log("##### queryByString queryString: " + queryString);

  // CouchDB Query
  // let iterator = await stub.getQueryResult(queryString);

  // Equivalent LevelDB Query. We need to parse queryString to determine what is being queried
  // In this chaincode, all queries will either query ALL records for a specific docType, or
  // they will filter ALL the records looking for a specific NGO, Donor, Donation, etc. So far, 
  // in this chaincode there is a maximum of one filter parameter in addition to the docType.
  let docType = "";
  let startKey = "";
  let endKey = "";
  let jsonQueryString = JSON.parse(queryString);
  if (jsonQueryString['selector'] && jsonQueryString['selector']['docType']) {
    docType = jsonQueryString['selector']['docType'];
    startKey = docType + "0";
    endKey = docType + "z";
  }
  else {
    throw new Error('##### queryByString - Cannot call queryByString without a docType element: ' + queryString);   
  }

  let iterator = await stub.getStateByRange(startKey, endKey);

  // Iterator handling is identical for both CouchDB and LevelDB result sets, with the 
  // exception of the filter handling in the commented section below
  let allResults = [];
  while (true) {
    let res = await iterator.next();

    if (res.value && res.value.value.toString()) {
      let jsonRes = {};
      console.log('##### queryByString iterator: ' + res.value.value.toString('utf8'));

      jsonRes.Key = res.value.key;
      try {
        jsonRes.Record = JSON.parse(res.value.value.toString('utf8'));
      } 
      catch (err) {
        console.log('##### queryByString error: ' + err);
        jsonRes.Record = res.value.value.toString('utf8');
      }
      // ******************* LevelDB filter handling ******************************************
      // LevelDB: additional code required to filter out records we don't need
      // Check that each filter condition in jsonQueryString can be found in the iterator json
      // If we are using CouchDB, this isn't required as rich query supports selectors
      let jsonRecord = jsonQueryString['selector'];
      // If there is only a docType, no need to filter, just return all
      console.log('##### queryByString jsonRecord - number of JSON keys: ' + Object.keys(jsonRecord).length);
      if (Object.keys(jsonRecord).length == 1) {
        allResults.push(jsonRes);
        continue;
      }
      for (var key in jsonRecord) {
        if (jsonRecord.hasOwnProperty(key)) {
          console.log('##### queryByString jsonRecord key: ' + key + " value: " + jsonRecord[key]);
          if (key == "docType") {
            continue;
          }
          console.log('##### queryByString json iterator has key: ' + jsonRes.Record[key]);
          if (!(jsonRes.Record[key] && jsonRes.Record[key] == jsonRecord[key])) {
            // we do not want this record as it does not match the filter criteria
            continue;
          }
          allResults.push(jsonRes);
        }
      }
      // ******************* End LevelDB filter handling ******************************************
      // For CouchDB, push all results
      // allResults.push(jsonRes);
    }
    if (res.done) {
      await iterator.close();
      console.log('##### queryByString all results: ' + JSON.stringify(allResults));
      console.log('============= END : queryByString ===========');
      return Buffer.from(JSON.stringify(allResults));
    }
  }
}