github.com/tenywen/fabric@v1.0.0-beta.0.20170620030522-a5b1ed380643/core/ledger/kvledger/example/marble_app.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 example

import (
	"encoding/json"
	"errors"
	"strconv"
	"strings"

	ledger "github.com/hyperledger/fabric/core/ledger"

	"github.com/hyperledger/fabric/protos/common"
	logging "github.com/op/go-logging"
)

var logger = logging.MustGetLogger("example")

// App - a sample fund transfer app
type MarbleApp struct {
	name   string
	ledger ledger.PeerLedger
}

// ConstructAppInstance constructs an instance of an app
func ConstructMarbleAppInstance(ledger ledger.PeerLedger) *MarbleApp {
	return &MarbleApp{"marbles_app", ledger}
}

type Marble struct {
	Name  string `json:"asset_name"` //the fieldtags are needed to keep case from bouncing around
	Color string `json:"color"`
	Size  int    `json:"size"`
	User  string `json:"owner"`
	Rev   string `json:"_rev"`
	Txid  string `json:"txid"`
}

// CreateMarble simulates init transaction
func (marbleApp *MarbleApp) CreateMarble(args []string) (*common.Envelope, error) {
	//   0       1       2     3
	// "asdf", "blue", "35", "bob"
	logger.Debugf("Entering ----------CreateMarble()----------")
	marbleName := args[0]
	marbleJsonBytes, err := init_marble(args)
	if err != nil {
		return nil, err
	}

	var txSimulator ledger.TxSimulator
	if txSimulator, err = marbleApp.ledger.NewTxSimulator(); err != nil {
		return nil, err
	}
	defer txSimulator.Done()

	txSimulator.SetState(marbleApp.name, marbleName, marbleJsonBytes)

	var txSimulationResults []byte
	if txSimulationResults, err = txSimulator.GetTxSimulationResults(); err != nil {
		return nil, err
	}
	logger.Debugf("CreateMarble() simulation done, packaging into a transaction...")
	tx := constructTransaction(txSimulationResults)
	logger.Debugf("Exiting CreateMarble()")
	return tx, nil
}

// ============================================================================================================================
// Init Marble - create a new marble, store into chaincode state
// ============================================================================================================================
func init_marble(args []string) ([]byte, error) {
	var err error

	//   0       1       2     3
	// "asdf", "blue", "35", "bob"
	if len(args) != 4 {
		return nil, errors.New("Incorrect number of arguments. Expecting 4")
	}

	logger.Debugf("Entering init marble")
	if len(args[0]) <= 0 {
		return nil, errors.New("1st argument must be a non-empty string")
	}
	if len(args[1]) <= 0 {
		return nil, errors.New("2nd argument must be a non-empty string")
	}
	if len(args[2]) <= 0 {
		return nil, errors.New("3rd argument must be a non-empty string")
	}
	if len(args[3]) <= 0 {
		return nil, errors.New("4th argument must be a non-empty string")
	}

	size, err := strconv.Atoi(args[2])
	if err != nil {
		return nil, errors.New("3rd argument must be a numeric string")
	}

	color := strings.ToLower(args[1])
	user := strings.ToLower(args[3])

	tx := "tx000000000000001" // COUCHDB hardcode a txid for now for demo purpose
	marbleJson := `{"txid": "` + tx + `",  "asset_name": "` + args[0] + `", "color": "` + color + `", "size": ` + strconv.Itoa(size) + `, "owner": "` + user + `"}`
	marbleBytes := []byte(marbleJson)

	logger.Debugf("Exiting init marble")
	return marbleBytes, nil
}

// TransferMarble simulates transfer transaction
func (marbleApp *MarbleApp) TransferMarble(args []string) (*common.Envelope, error) {
	//   0       1
	// "name", "bob"
	if len(args) < 2 {
		return nil, errors.New("Incorrect number of arguments. Expecting 2")
	}
	marbleName := args[0]
	marbleNewOwner := args[1]

	logger.Debugf("Entering ----------TransferMarble----------")
	var txSimulator ledger.TxSimulator
	var err error
	if txSimulator, err = marbleApp.ledger.NewTxSimulator(); err != nil {
		return nil, err
	}
	defer txSimulator.Done()

	marbleBytes, err := txSimulator.GetState(marbleApp.name, marbleName)
	logger.Debugf("marbleBytes is: %v", marbleBytes)
	if marbleBytes != nil {
		jsonString := string(marbleBytes[:])
		logger.Debugf("TransferMarble() Retrieved jsonString: \n   %s", jsonString)
	}

	theMarble := Marble{}
	json.Unmarshal(marbleBytes, &theMarble) //Unmarshal JSON bytes into a Marble struct

	logger.Debugf(" theMarble after unmarshal: %v", theMarble)

	logger.Debugf(" Setting the owner to: %s", marbleNewOwner)
	theMarble.User = marbleNewOwner      //change the user
	theMarble.Txid = "tx000000000000002" // COUCHDB hardcode a txid for now for demo purpose

	updatedMarbleBytes, _ := json.Marshal(theMarble)
	if updatedMarbleBytes != nil {
		updatedJsonString := string(updatedMarbleBytes[:])
		logger.Debugf("updatedJsonString:\n   %s", updatedJsonString)
	}
	err = txSimulator.SetState(marbleApp.name, marbleName, updatedMarbleBytes)
	if err != nil {
		return nil, err
	}

	var txSimulationResults []byte
	if txSimulationResults, err = txSimulator.GetTxSimulationResults(); err != nil {
		return nil, err
	}
	logger.Debugf("TransferMarble() simulation done, packaging into a transaction...")
	tx := constructTransaction(txSimulationResults)
	return tx, nil
}