Error

https://middlemost.com/failure-is-your-domain/

Failure is your Domain

A blog post: Golang Error Handling — Best Practice in 2020
https://itnext.io/golang-error-handling-best-practice-a36f47b0b94c?gi=4aa392168c6d

Golang Error Handling — Best Practice in 2020

처음 logrus, console에서 나름 정해진 규칙에 맞게 로그를 찍어오다가

# 1
trackingCodeNotFound := strings.Contains(err.Error(), "Cnote No. Not Found.")

// xxx.go
var ErrCnoteNumberNotFound = errors.New("~~ Cnote No. Not Found. ~~")

func getTrackStatus() error {
  return fmt.Errorf("Grab: %w", ErrCnoteNumberNotFound)
}

//
err := getTrackStatus()
trackingCodeNotFound := errors.Is(err, ErrCnoteNumberNotFound)

# 2
return nil, errors.New("not implemented")

Datadog을 도입하면서 Log를 Wrapping 해야지 찾기 쉽다는걸 느꼈다.

GRPC를 사용하면서 https://cloud.google.com/apis/design/errors

오류  |  Cloud API  |  Google Cloud

에러 디자인을 참조하고,

# specific service error
enum Error {
	Error_Unused = 0; // The first enum value must be zero in proto3.
	RecordNotFound = 1;
	Forbidden = 2;
	RecordCreate = 3;
	InvalidRequestBody = 4;
	InvalidParam = 5;
	InvalidQuery = 6;
	Internal = 7;
	NoneExistingLineItem = 8;
	ProductNotAvailable = 9;
	ProductIsNotActive = 10;
	ProductIsNotReleasedYet = 11;
	ProductIsNotPublishedYet = 12;
	ProductIsNotPublishedAnymore = 13;
	CartDoesNotHaveItems = 14;
	LessThanMinQuanity = 15;
	ExceedsMaxQuantity = 16;
	CartProductTypeMismatch = 17;
	InvalidCartItemNoteType = 18;
	ItemNoteIsNotInCart = 19;
	NeedToStartTransaction = 20;
	TransactionAlreadyStarted = 21;
	InvalidQuantity = 22;
	InvalidFreeItemSelection = 23;
	ProductNotFound = 24;
	InputNoteRequired = 25;
	InputNoteFieldRequired = 26;
	BundleItemNotFound = 27;
	BundledProductNotFound = 28;
	ProductOutOfStock = 29;
	CartIsEmpty = 30;
	ShippingRateNotFound = 31;
	InvalidVoucherCondition = 32;
	InactiveVoucher = 33;
}

# common error
enum Error {
	Error_Unused = 0; // The first enum value must be zero in proto3.
	RecordNotFound = 1;
	Forbidden = 2;
	RecordCreate = 3;
	InvalidRequestBody = 4;
	InvalidParam = 5;
	InvalidQuery = 6;
	Internal = 7;
}

// NewError - Create an error with code and message
func NewError(code errors.Error, message string) *commonerror.Error {
	return factory.NewError(code, message)
}

// WrapError - Wrap other library error with our error code
func WrapError(code errors.Error, err error) *commonerror.Error {
	return factory.WrapError(code, err)
}

// SimpleError - Create an error with just code. Message came from predefined string or enum name
func SimpleError(code errors.Error) *commonerror.Error {
	return factory.SimpleError(code)
}

// GetErrorCode - Return idl defined error code if passed error is commonerrors.Error type
func GetErrorCode(e error) errors.Error {
	err, ok := e.(*commonerror.Error)
	if !ok {
		return -1
	}
	return errors.Error(err.Code)
}

// Is - Return true if passed error is commonerrors.Error type and error code is same as passed code
func Is(e error, expected errors.Error) bool {
	code := GetErrorCode(e)
	return code == expected
}

// GetDetail - Return detail if passed error is commonerrors.Error type
func GetDetail(e error) interface{} {
	err, ok := e.(*commonerror.Error)
	if !ok {
		return nil
	}
	return err.Detail
}

로 Wrap해서 같은 방식으로 추적하기 편하게 변경하