Cars chaincode example

cars_chaincode_example.go

// Simple CRUD chaincode for store information about cars
package cars

import (
	"errors"
	"time"

	"github.com/hyperledger/fabric/core/chaincode/shim"
	"github.com/hyperledger/fabric/protos/peer"
	"github.com/s7techlab/cckit/extensions/owner"
	"github.com/s7techlab/cckit/router"
	p "github.com/s7techlab/cckit/router/param"
)

var (
	ErrCarAlreadyExists = errors.New(`car already exists`)
)

const CarEntity = `CAR`
const CarRegisteredEvent = `CAR_REGISTERED`

// CarPayload chaincode method argument
type CarPayload struct {
	Id    string
	Title string
	Owner string
}

// Car struct for chaincode state
type Car struct {
	Id    string
	Title string
	Owner string

	UpdatedAt time.Time // set by chaincode method
}

// Key for car entry in chaincode state
func (c Car) Key() ([]string, error) {
	return []string{CarEntity, c.Id}, nil
}

type Chaincode struct {
	router *router.Group
}

func New() *Chaincode {
	r := router.New(`cars`) // also initialized logger with "cars" prefix

	r.Group(`car`).
		Query(`List`, cars).                                            // chain code method name is carList
		Query(`Get`, car, p.String(`id`)).                              // chain code method name is carGet, method has 1 string argument "id"
		Invoke(`Register`, carRegister, p.Struct(`car`, &CarPayload{}), // 1 struct argument
			owner.Only) // allow access to method only for chaincode owner (authority)

	return &Chaincode{r}
}

//========  Base methods ====================================
//
// Init initializes chain code - sets chaincode "owner"
func (cc *Chaincode) Init(stub shim.ChaincodeStubInterface) peer.Response {
	// set owner of chain code with special permissions , based on tx creator certificate
	// owner info stored in chaincode state as entry with key "OWNER" and content is serialized "Grant" structure
	return owner.SetFromCreator(cc.router.Context(`init`, stub))
}

// Invoke - entry point for chain code invocations
func (cc *Chaincode) Invoke(stub shim.ChaincodeStubInterface) peer.Response {
	// delegate handling to router
	return cc.router.Handle(stub)
}

// ======= Chaincode methods

// car get info chaincode method handler
func car(c router.Context) (interface{}, error) {

	// get state entry by composite key using CarKeyPrefix and car.Id
	//  and unmarshal from []byte to Car struct
	return c.State().Get(&Car{Id: c.ArgString(`id`)})
}

// cars car list chaincode method handler
func cars(c router.Context) (interface{}, error) {
	return c.State().List(
		CarEntity, // get list of state entries of type CarKeyPrefix
		&Car{})    // unmarshal from []byte and append to []Car slice
}

// carRegister car register chaincode method handler
func carRegister(c router.Context) (interface{}, error) {
	// arg name defined in router method definition
	p := c.Arg(`car`).(CarPayload)

	t, _ := c.Time() // tx time
	car := &Car{     // data for chaincode state
		Id:        p.Id,
		Title:     p.Title,
		Owner:     p.Owner,
		UpdatedAt: t,
	}

	// trigger event
	c.SetEvent(CarRegisteredEvent, car)

	return car, // peer.Response payload will be json serialized car data
		//put json serialized data to state
		// create composite key using CarKeyPrefix and car.Id
		c.State().Insert(car)
}