Hyperledger Fabric JSON response has backslashes - json

Question

I'm currently testing a Hyperledger Fabric Application, but I get an unexpected JSON response.
Why are there extra backslashes between every object in the response?
result, err := json.Marshal(history)
logger.Debug(string(result))
if err != nil {
message := fmt.Sprintf("unable to marshal the result: %s", err.Error())
logger.Error(message)
return shim.Error(message)
}
logger.Info("SimpleChaincode.getHistory exited successfully")
return shim.Success(result)
Actual CLI output:
Chaincode invoke successful. result: status:200 payload:"[{\"type\":\"history\",\"key\":\"key\",\"values\":[{\"tx_id\":\"723a398362282d92f7b05b821fc8f835736b6068e5d1b72d105fc86d6e57d64e\",\"value\":\"initial_value\",\"is_delete\":false}]}]"
Expected CLI result:
Chaincode invoke successful.
result: status:200
payload:
[
{
"type":"history",
"key":"key",
"values":[
{
"tx_id":"723a398362282d92f7b05b821fc8f835736b6068e5d1b72d105fc86d6e57d64e",
"value":"initial_value",
"is_delete":false
}
]
}
]
Docker logs:
2020-08-19 14:40:18.823 UTC [SimpleChaincode] Debug -> DEBU 015 [{"type":"history","key":"key","values":[{"tx_id":"723a398362282d92f7b05b821fc8f835736b6068e5d1b72d105fc86d6e57d64e","value":"initial_value","is_delete":false}]}]
2020-08-19 14:40:18.823 UTC [SimpleChaincode] Info -> INFO 016 SimpleChaincode.getHistory exited successfully

Answer 1

Logging format
The logging format of the peer and orderer commands is controlled via the FABRIC_LOGGING_FORMAT environment variable. This can be set to a format string, such as the default
"%{color}%{time:2006-01-02 15:04:05.000 MST} [%{module}] %{shortfunc} -> %{level:.4s} %{id:03x}%{color:reset} %{message}"
to print the logs in a human-readable console format. It can be also set to json to output logs in JSON format.
Link: https://hyperledger-fabric.readthedocs.io/en/release-2.2/logging-control.html#logging-format
You can update core.yaml or you can use "FABRIC_LOGGING_FORMAT" in your docker compose file.
An example with core.yaml is given below:
# Logging section for the chaincode container
logging:
# Default level for all loggers within the chaincode container
level: info
# Override default level for the 'shim' logger
shim: warning
# Format for the chaincode container logs
format: json
You can find core.yaml into "fabric-samples/config" directory.
Link: https://github.com/hyperledger/fabric/blob/master/sampleconfig/core.yaml
If you download latest fabric samples, you can find sample core.yaml at "fabric-samples/config" directory.
An example with "FABRIC_LOGGING_FORMAT" in your docker compose file is given below:
You have to edit the environment of cli container with "- FABRIC_LOGGING_FORMAT=json"
cli:
container_name: cli
image: hyperledger/fabric-tools:$IMAGE_TAG
tty: true
stdin_open: true
environment:
- GOPATH=/opt/gopath
- CORE_VM_ENDPOINT=unix:///host/var/run/docker.sock
#- FABRIC_LOGGING_SPEC=DEBUG
- FABRIC_LOGGING_FORMAT=json
- FABRIC_LOGGING_SPEC=INFO
- CORE_PEER_ID=cli
- CORE_PEER_ADDRESS=peer0.org1.example.com:7051
- CORE_PEER_LOCALMSPID=Org1MSP
- CORE_PEER_TLS_ENABLED=true
- CORE_PEER_TLS_CERT_FILE=/opt/gopath/src/github.com/hyperledger/fabric/peer/crypto/peerOrganizations/org1.example.com/peers/peer0.org1.example.com/tls/server.crt
- CORE_PEER_TLS_KEY_FILE=/opt/gopath/src/github.com/hyperledger/fabric/peer/crypto/peerOrganizations/org1.example.com/peers/peer0.org1.example.com/tls/server.key
- CORE_PEER_TLS_ROOTCERT_FILE=/opt/gopath/src/github.com/hyperledger/fabric/peer/crypto/peerOrganizations/org1.example.com/peers/peer0.org1.example.com/tls/ca.crt
- CORE_PEER_MSPCONFIGPATH=/opt/gopath/src/github.com/hyperledger/fabric/peer/crypto/peerOrganizations/org1.example.com/users/Admin#org1.example.com/msp
working_dir: /opt/gopath/src/github.com/hyperledger/fabric/peer
command: /bin/bash
volumes:
- /var/run/:/host/var/run/
- ./../chaincode/:/opt/gopath/src/github.com/hyperledger/fabric-samples/chaincode
- ./crypto-config:/opt/gopath/src/github.com/hyperledger/fabric/peer/crypto/
- ./scripts:/opt/gopath/src/github.com/hyperledger/fabric/peer/scripts/
- ./channel-artifacts:/opt/gopath/src/github.com/hyperledger/fabric/peer/channel-artifacts
depends_on:
- orderer.example.com
- peer0.org1.example.com
- peer1.org1.example.com
- peer0.org2.example.com
- peer1.org2.example.com
networks:
- byfn