chaincode_example04.go

/*
Copyright IBM Corp. 2016 All Rights Reserved.

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

		 http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/

package main

import (
	"fmt"
	"strconv"

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

// This chaincode is a test for chaincode invoking another chaincode - invokes chaincode_example02

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

// Init takes two arguments, a string and int. These are stored in the key/value pair in the state
func (t *SimpleChaincode) Init(stub shim.ChaincodeStubInterface) pb.Response {
	var event string // Indicates whether event has happened. Initially 0
	var eventVal int // State of event
	var err error
	_, args := stub.GetFunctionAndParameters()
	if len(args) != 2 {
		return shim.Error("Incorrect number of arguments. Expecting 2")
	}

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

	err = stub.PutState(event, []byte(strconv.Itoa(eventVal)))
	if err != nil {
		return shim.Error(err.Error())
	}

	return shim.Success(nil)
}

// Invoke invokes another chaincode - chaincode_example02, upon receipt of an event and changes event state
func (t *SimpleChaincode) invoke(stub shim.ChaincodeStubInterface, args []string) pb.Response {
	var event string // Event entity
	var eventVal int // State of event
	var err error

	if len(args) != 3 && len(args) != 4 {
		return shim.Error("Incorrect number of arguments. Expecting 3 or 4")
	}

	chainCodeToCall := args[0]
	event = args[1]
	eventVal, err = strconv.Atoi(args[2])
	if err != nil {
		return shim.Error("Expected integer value for event state change")
	}
	channelID := ""
	if len(args) == 4 {
		channelID = args[3]
	}

	if eventVal != 1 {
		fmt.Printf("Unexpected event. Doing nothing\n")
		return shim.Success(nil)
	}

	f := "invoke"
	invokeArgs := util.ToChaincodeArgs(f, "a", "b", "10")
	response := stub.InvokeChaincode(chainCodeToCall, invokeArgs, channelID)
	if response.Status != shim.OK {
		errStr := fmt.Sprintf("Failed to invoke chaincode. Got error: %s", string(response.Payload))
		fmt.Printf(errStr)
		return shim.Error(errStr)
	}

	fmt.Printf("Invoke chaincode successful. Got response %s", string(response.Payload))

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

	return response
}

func (t *SimpleChaincode) query(stub shim.ChaincodeStubInterface, args []string) pb.Response {
	var event string // Event entity
	var err error

	if len(args) < 1 {
		return shim.Error("Incorrect number of arguments. Expecting entity to query")
	}

	event = args[0]
	var jsonResp string

	// Get the state from the ledger
	eventValbytes, err := stub.GetState(event)
	if err != nil {
		jsonResp = "{\"Error\":\"Failed to get state for " + event + "\"}"
		return shim.Error(jsonResp)
	}

	if eventValbytes == nil {
		jsonResp = "{\"Error\":\"Nil value for " + event + "\"}"
		return shim.Error(jsonResp)
	}

	if len(args) > 3 {
		chainCodeToCall := args[1]
		queryKey := args[2]
		channel := args[3]
		f := "query"
		invokeArgs := util.ToChaincodeArgs(f, queryKey)
		response := stub.InvokeChaincode(chainCodeToCall, invokeArgs, channel)
		if response.Status != shim.OK {
			errStr := fmt.Sprintf("Failed to invoke chaincode. Got error: %s", err.Error())
			fmt.Printf(errStr)
			return shim.Error(errStr)
		}
		jsonResp = string(response.Payload)
	} else {
		jsonResp = "{\"Name\":\"" + event + "\",\"Amount\":\"" + string(eventValbytes) + "\"}"
	}
	fmt.Printf("Query Response: %s\n", jsonResp)

	return shim.Success([]byte(jsonResp))
}

// Invoke is called by fabric to execute a transaction
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.Error("Invalid invoke function name. Expecting \"invoke\" \"query\"")
}

func main() {
	err := shim.Start(new(SimpleChaincode))
	if err != nil {
		fmt.Printf("Error starting Simple chaincode: %s", err)
	}
}