chaincode.go

/*
Copyright IBM Corp. All Rights Reserved.

SPDX-License-Identifier: Apache-2.0
*/

package example05

import (
	"fmt"
	"strconv"

	"github.com/hyperledger/fabric/core/chaincode/shim"
	pb "github.com/hyperledger/fabric/protos/peer"
)

// This chaincode is a test for chaincode querying another chaincode - invokes chaincode_example02 and computes the sum of a and b and stores it as state

// SimpleChaincode example simple Chaincode implementation
type SimpleChaincode struct{}

func toChaincodeArgs(args ...string) [][]byte {
	bargs := make([][]byte, len(args))
	for i, arg := range args {
		bargs[i] = []byte(arg)
	}
	return bargs
}

// Init takes two arguments, a string and int. The string will be a key with
// the int as a value.
func (t *SimpleChaincode) Init(stub shim.ChaincodeStubInterface) pb.Response {
	var sum string // Sum of asset holdings across accounts. Initially 0
	var sumVal int // Sum of holdings
	var err error
	_, args := stub.GetFunctionAndParameters()
	if len(args) != 2 {
		return shim.Error("Incorrect number of arguments. Expecting 2")
	}

	// Initialize the chaincode
	sum = args[0]
	sumVal, err = strconv.Atoi(args[1])
	if err != nil {
		return shim.Error("Expecting integer value for sum")
	}
	fmt.Printf("sumVal = %d\n", sumVal)

	// Write the state to the ledger
	err = stub.PutState(sum, []byte(strconv.Itoa(sumVal)))
	if err != nil {
		return shim.Error(err.Error())
	}

	return shim.Success(nil)
}

// Invoke queries another chaincode and updates its own state
func (t *SimpleChaincode) invoke(stub shim.ChaincodeStubInterface, args []string) pb.Response {
	var sum, channelName string // Sum entity
	var Aval, Bval, sumVal int  // value of sum entity - to be computed
	var err error

	if len(args) < 2 {
		return shim.Error("Incorrect number of arguments. Expecting atleast 2")
	}

	chaincodeName := args[0] // Expecting name of the chaincode you would like to call, this name would be given during chaincode install time
	sum = args[1]

	if len(args) > 2 {
		channelName = args[2]
	} else {
		channelName = ""
	}

	// Query chaincode_example02
	f := "query"
	queryArgs := toChaincodeArgs(f, "a")

	//   if chaincode being invoked is on the same channel,
	//   then channel defaults to the current channel and args[2] can be "".
	//   If the chaincode being called is on a different channel,
	//   then you must specify the channel name in args[2]

	response := stub.InvokeChaincode(chaincodeName, queryArgs, channelName)
	if response.Status != shim.OK {
		errStr := fmt.Sprintf("Failed to query chaincode. Got error: %s", response.Payload)
		fmt.Printf(errStr)
		return shim.Error(errStr)
	}
	Aval, err = strconv.Atoi(string(response.Payload))
	if err != nil {
		errStr := fmt.Sprintf("Error retrieving state from ledger for queried chaincode: %s", err.Error())
		fmt.Printf(errStr)
		return shim.Error(errStr)
	}

	queryArgs = toChaincodeArgs(f, "b")
	response = stub.InvokeChaincode(chaincodeName, queryArgs, channelName)
	if response.Status != shim.OK {
		errStr := fmt.Sprintf("Failed to query chaincode. Got error: %s", response.Payload)
		fmt.Printf(errStr)
		return shim.Error(errStr)
	}
	Bval, err = strconv.Atoi(string(response.Payload))
	if err != nil {
		errStr := fmt.Sprintf("Error retrieving state from ledger for queried chaincode: %s", err.Error())
		fmt.Printf(errStr)
		return shim.Error(errStr)
	}

	// Compute sum
	sumVal = Aval + Bval

	// Write sumVal back to the ledger
	err = stub.PutState(sum, []byte(strconv.Itoa(sumVal)))
	if err != nil {
		return shim.Error(err.Error())
	}

	fmt.Printf("Invoke chaincode successful. Got sum %d\n", sumVal)
	return shim.Success([]byte(strconv.Itoa(sumVal)))
}

func (t *SimpleChaincode) query(stub shim.ChaincodeStubInterface, args []string) pb.Response {
	var sum, channelName string // Sum entity
	var Aval, Bval, sumVal int  // value of sum entity - to be computed
	var err error

	if len(args) < 2 {
		return shim.Error("Incorrect number of arguments. Expecting atleast 2")
	}

	chaincodeName := args[0] // Expecting name of the chaincode you would like to call, this name would be given during chaincode install time
	sum = args[1]

	if len(args) > 2 {
		channelName = args[2]
	} else {
		channelName = ""
	}

	// Query chaincode_example02
	f := "query"
	queryArgs := toChaincodeArgs(f, "a")

	//   if chaincode being invoked is on the same channel,
	//   then channel defaults to the current channel and args[2] can be "".
	//   If the chaincode being called is on a different channel,
	//   then you must specify the channel name in args[2]
	response := stub.InvokeChaincode(chaincodeName, queryArgs, channelName)
	if response.Status != shim.OK {
		errStr := fmt.Sprintf("Failed to query chaincode. Got error: %s", response.Payload)
		fmt.Printf(errStr)
		return shim.Error(errStr)
	}
	Aval, err = strconv.Atoi(string(response.Payload))
	if err != nil {
		errStr := fmt.Sprintf("Error retrieving state from ledger for queried chaincode: %s", err.Error())
		fmt.Printf(errStr)
		return shim.Error(errStr)
	}

	queryArgs = toChaincodeArgs(f, "b")
	response = stub.InvokeChaincode(chaincodeName, queryArgs, channelName)
	if response.Status != shim.OK {
		errStr := fmt.Sprintf("Failed to query chaincode. Got error: %s", response.Payload)
		fmt.Printf(errStr)
		return shim.Error(errStr)
	}
	Bval, err = strconv.Atoi(string(response.Payload))
	if err != nil {
		errStr := fmt.Sprintf("Error retrieving state from ledger for queried chaincode: %s", err.Error())
		fmt.Printf(errStr)
		return shim.Error(errStr)
	}

	// Compute sum
	sumVal = Aval + Bval

	fmt.Printf("Query chaincode successful. Got sum %d\n", sumVal)
	jsonResp := "{\"Name\":\"" + sum + "\",\"Value\":\"" + strconv.Itoa(sumVal) + "\"}"
	fmt.Printf("Query Response:%s\n", jsonResp)
	return shim.Success([]byte(strconv.Itoa(sumVal)))
}

func (t *SimpleChaincode) Invoke(stub shim.ChaincodeStubInterface) pb.Response {
	function, args := stub.GetFunctionAndParameters()
	if function == "invoke" {
		return t.invoke(stub, args)
	} else if function == "query" {
		return t.query(stub, args)
	}

	return shim.Success([]byte("Invalid invoke function name. Expecting \"invoke\" \"query\""))
}