How to Query Chaincode Property on BYFN Channel?

An instance of a chaincode can be viewed as an object of a class in an execution environment. It can hold properties.

You can run the "peer chaincode query" command to query the current value of a given property of a given chaincode instance.

1. Verify instantiated chaincode:

$ docker exec -it cli bash

bash-4.4# echo $CORE_PEER_ADDRESS
peer0.org2.example.com:7051

bash-4.4# peer chaincode list -C mychannel --instantiated
Get instantiated chaincodes on channel mychannel:
Name: mycc, Version: 1.0, Path: github.com/chaincode/chaincode_example02/go/, \
   Escc: escc, Vscc: vscc

2. Query property "a" and "b" of instantiated chaincode "mycc":

bash-4.4# peer chaincode query -C mychannel -n mycc -c '{"Args":["query","a"]}'
100

bash-4.4# peer chaincode query -C mychannel -n mycc -c '{"Args":["query","b"]}'
200

3. Query an unknown property "c":

bash-4.4# peer chaincode query -C mychannel -n mycc -c '{"Args":["query","c"]}'

Error: endorsement failure during query. response: status:500 \
   message:"{\"Error\":\"Nil amount for c\"}"

4. Query an unknown chaincode instance:

bash-4.4# peer chaincode query -C mychannel -n mycc_x -c '{"Args":["query","a"]}'

Error: endorsement failure during query. response: status:500 \
message:"make sure the chaincode mycc_x has been successfully instantiated \
and try again: chaincode mycc_x not found"

 

⇒ Invoke Chaincode Transaction on BYFN Channel

⇐ Instantiate Chaincode on BYFN Channel

⇑ BYFN (Build Your First Network)

⇑⇑ Hyperledger Tutorials