Hyperledger not-complete chaincode example from Fabcar

chaincode.go

// Define the Smart Contract structure
type SmartContract struct { }

// Define the car structure, with 4 properties.
type Car struct {
  Make   string `json:"make"`
  Model  string `json:"model"`
  Colour string `json:"colour"`
  Owner  string `json:"owner"`
}

/*
 * The Invoke method is called as a result of an application request to run the Smart Contract "fabcar"
 * The calling application program has also specified the particular smart contract function to be called, with arguments
 */
func (s *SmartContract) Invoke(APIstub shim.ChaincodeStubInterface) sc.Response {
  
  // Retrieve the requested Smart Contract function and arguments
  function, args := APIstub.GetFunctionAndParameters()
  
  // Route to the appropriate handler function to interact with the ledger appropriately
  if function == "initLedger" {
    return s.initLedger(APIstub)
  } else if function == "createCar" {
    return s.createCar(APIstub, args)
  }
  
  return shim.Error("Invalid Smart Contract function name.")
}

func (s *SmartContract) initLedger(APIstub shim.ChaincodeStubInterface) sc.Response {
  return shim.Success([]byte("Ledger is now running, success!"))
}

// Add new car to database with obtained arguments
func (s *SmartContract) createCar(APIstub shim.ChaincodeStubInterface, args []string) sc.Response {
  
  if len(args) != 5 {
    return shim.Error("Incorrect number of arguments. Expecting 5")
  }
  
  var car = Car{Make: args[1], Model: args[2], Colour: args[3], Owner: args[4]}
  carAsBytes, _ := json.Marshal(car)
  
  APIstub.PutState(args[0], carAsBytes)
  
  return shim.Success(nil)
}

func main() {
  // Create a new Smart Contract
  err := shim.Start(new(SmartContract))
  
  if err != nil {
    fmt.Printf("Error creating new Smart Contract: %s", err)
  }
}