records user name to the ledger

write.go

package main

import (
	"github.com/op/go-logging"
	"os"
	"github.com/hyperledger/fabric/core/chaincode/shim"
	pb "github.com/hyperledger/fabric/protos/peer"
	"github.com/hyperledger/fabric/core/chaincode/lib/cid"
)

var logger = logging.MustGetLogger("acl")
var format = logging.MustStringFormatter(
	`%{color}%{time:15:04:05.000} %{shortfunc} ▶ %{level:.8s} %{id:03x}%{color:reset} %{message}`,
)

var user_name string

type SimpleChaincode struct {
}

func (t *SimpleChaincode) Init(stub shim.ChaincodeStubInterface) pb.Response {
	logger.Debug("Initializing SimpleChaincode")
	resp := "Initialized"
	logger.Debug(resp)
	return shim.Success([]byte(resp))
}

func (t *SimpleChaincode) Invoke(stub shim.ChaincodeStubInterface) pb.Response {
	logger.Debug("Invoking Chaincode...")
	function, args := stub.GetFunctionAndParameters()
	if function == "write_to_ledger" {
		return t.write_to_ledger(stub, args)
	}
	
	return shim.Error("Invalid invoke function name. Expecting \"write_to_ledger\" or \"get_attribute\".")
}

func (t* SimpleChaincode) write_to_ledger(stub shim.ChaincodeStubInterface, args []string) pb.Response {
	logger.Debug("Invoking write_to_ledger")

	var user_name string
	val, ok, err := cid.GetAttributeValue(stub, "hf.EnrollmentID")
	if err != nil {
		return shim.Error(err.Error())
	}
	if ok {
		user_name = val
	}
	err = stub.PutState(user_name, []byte(user_name + " can write to ledger"))
	if err != nil {
		return shim.Error(err.Error())
	}
	
	return shim.Success([]byte(user_name + " wrote to ledger"))
}

func main() {
	backend1 := logging.NewLogBackend(os.Stderr, "", 0)
	backend2 := logging.NewLogBackend(os.Stderr, "", 0)

	// For messages written to backend2 we want to add some additional
	// information to the output, including the used log level and the name of
	// the function.
	backend2Formatter := logging.NewBackendFormatter(backend2, format)

	// Only errors and more severe messages should be sent to backend1
	backend1Leveled := logging.AddModuleLevel(backend1)
	backend1Leveled.SetLevel(logging.ERROR, "")

	logging.SetBackend(backend1Leveled, backend2Formatter)

	logger.Debug("Starting SimpleChaincode")
	err := shim.Start(new(SimpleChaincode))
	if err != nil {
		logger.Errorf("Error starting Simple chaincode: %s", err)
	}
}