Cannot get state in Hyperledger fabric correctly? - hyperledger-fabric

Question

Problem:
I have developed a Hyperledger fabric network and after that, I install a chain code in there. This is my Initialize ledger methods looks like.
async initLedger(stub, args) {
console.info("============= START : Initialize Ledger ===========");
let drivers = [];
drivers.push({
nic: "123",
firstName: "Saman",
lastName: "Frenando",
status: "Not verified",
licenceNo: "1234"
});
drivers.push({
nic: "124",
firstName: "Janith",
lastName: "Bentharaarachchi",
status: "Not verified",
licenceNo: "1235"
});
for (let i = 0; i < drivers.length; i++) {
drivers[i].docType = "driver";
console.log(drivers[i].nic);
await stub.putState(
drivers[i].nic,
Buffer.from(JSON.stringify(drivers[i]))
);
console.info("Added <--> ", drivers[i]);
}
console.info("============= END : Initialize Ledger ===========");
}
This is how I am retrieving those data.
async selectNthDriver(stub, args) {
if (args.length != 1) {
throw new Error(
"Incorrect number of arguments. Expecting NIC ex: 123"
);
}
let nic = args[0];
console.log(`nic: ${nic}`);
let driverAsBytes = await stub.getState(nic);
console.log("hi"+driverAsBytes);
if (!driverAsBytes || driverAsBytes.toString().length <= 0) {
throw new Error("Driver with NIC" + nic + " does not exist");
}
console.log(driverAsBytes.toString());
return driverAsBytes;
}
When I am Issuing this command on peer it successfully initializes the ledger.
peer chaincode invoke -o orderer.example.com:7050 --tls --cafile /opt/gopath/src/github.com/hyperledger/fabric/peer/crypto/ordererOrganizations/example.com/orderers/orderer.example.com/msp/tlscacerts/tlsca.example.com-cert.pem -C myc -n mycc -c '{"Args":["initLedger"]}'
By Issuing the following command when I try to retrieve a driver it leaves me an error by saying this.
Error: endorsement failure during invoke. response: status:500 message:"transaction returned with failure: Error: Driver with NIC123 does not exist"
peer chaincode invoke -o orderer.example.com:7050 --tls --cafile /opt/gopath/src/github.com/hyperledger/fabric/peer/crypto/ordererOrganizations/example.com/orderers/orderer.example.com/msp/tlscacerts/tlsca.example.com-cert.pem -C myc -n mycc -c '{"Args":["selectNthDriver","123"]}
This is the chaincode logs.
2019-05-09T05:18:51.184Z info [lib/handler.js]
info: [myc-09f261c4] Calling chaincode Init() succeeded.
Sending COMPLETED message back to peer
{"timestamp":"2019-05-09T05:18:51.184Z"} { fcn: 'initLedger', params:
[] }
============= START : Initialize Ledger =========== 123 Added <--> { nic: '123', firstName: 'Saman', lastName: 'Fernando', status:
'Not verified', licenceNo: '1234', docType: 'driver' } 124 Added
<--> { nic: '124', firstName: 'Janith', lastName:
'Bentharaarachchi', status: 'Not verified', licenceNo: '1235',
docType: 'driver' }
============= END : Initialize Ledger =========== { fcn: 'selectNthDriver', params: [ '123' ] } nic: 123 hi
Error: Driver with NIC123 does not exist
at selectNthDriver (/usr/local/src/mycc.js:494:13)
at
at process._tickCallback (internal/process/next_tick.js:188:7) 2019-05-09T05:43:42.430Z error [lib/handler.js]
error: [myc-e7aef847] Calling chaincode Invoke() returned
error response [Error: Driver with NIC123 does not exist].
Sending ERROR message back to peer
{"timestamp":"2019-05-09T05:43:42.430Z"}
And when I go to the CouchDB through browser It is not showing the data I initialized. It only shows this data.
{
"_id": "mycc",
"_rev": "1-5c5ecfec35f65ec74cbe52a52be96048",
"~version": "\u0000CgMBBwA=",
"_attachments": {
"valueBytes": {
"content_type": "application/octet-stream",
"revpos": 1,
"digest": "md5-SkPMcpW++nrvo5v00rCdRQ==",
"length": 424,
"stub": true
}
}
}
Can someone help me to find where am I doing wrong? Thank you.

Answer 1

You should use "query" command for querying a state from the ledger using the peer binary, the invoke command which you have used is for generating a transaction, which is not required for a query operation.
You should just try replacing invoke with query and it should look something like this:
peer chaincode query -o orderer.example.com:7050 -C myc -n mycc -c '{"Args":["selectNthDriver","123"]}
EDIT: Also please check for the following condition in your if statement in the selectNthDriver Method:
if (!driverAsBytes.toString())
Also please console for the same(driverAsBytes.toString()) in the line just before this if statement in your code.