GO Error Lib

Overview

This is the library that defines errors and error handlers for Golang API application

Add this lib to your project

• Step 1:

$ export GOPRIVATE=github.com/anhvietnguyennva/go-error

• Step 2: Add file tools/tools.go with content:

package tools

import (
	_ "github.com/anhvietnguyennva/go-error/tools"
)

• Step 3:

$ go mod tidy
$ go mod vendor

Update to latest version

$ go get -u github.com/anhvietnguyennva/go-error
$ go mod vendor

How to use

InfraError

These errors should be used in the infra layer (repository) of your service.

DomainError

These errors should be used in the domain layer of your service.

RestAPIError

These errors should be used in the application interface of your service.

Transforms DomainError to RestAPIError

package main

import (
	"fmt"
	
	"github.com/anhvietnguyennva/go-error/pkg/errors"
	t "github.com/anhvietnguyennva/go-error/pkg/transformer"
)

func main() {
	domainErr := errors.NewDomainErrorNotFound(nil)
	transformer := t.RestTransformerInstance()
	apiErr := transformer.DomainErrToRestAPIErr(domainErr)
	fmt.Println(apiErr.Error())
}

• NOTE
  • Transforming InfraError to DomainError is done in a similar way.
  • Transform errors flow: InfraError(if exists) => DomainError => ClientError (RestAPIError, RPCError)

Register new DomainError and new RestAPIError

• There are functions can be used to create customized errors. With DomainError, it's errors.NewDomainError(code string, message string, entities []string, rootCause error) and it's errors.NewRestAPIError(httpStatus int, code int, message string, entities []string, rootCause error) with RestAPIError.
• You can use these above functions to create your customized errors directly. But you should define new constructors for your custom errors, so it can be reused. For example:

package main

import (
	"net/http"
	
	"github.com/anhvietnguyennva/go-error/pkg/errors"
)

const (
	DomainErrCodeCustomized = "DOMAIN:CUSTOMIZED"
	DomainErrMsgCustomized  = "Customized domain error"

	ClientErrCodeCustomized = 40099
	ClientErrMsgCustomized  = "Customized client error"
) 

func NewDomainErrCustomized(rootCause error, entities ...string) *errors.DomainError {
	return errors.NewDomainError(DomainErrCodeCustomized, DomainErrMsgCustomized, entities, rootCause)
}

func NewRestAPIErrCustomized(rootCause error, entities ...string) *errors.RestAPIError {
	message := errors.AppendEntitiesToErrMsg(ClientErrMsgCustomized, entities)
	return errors.NewRestAPIError(http.StatusBadRequest, ClientErrCodeCustomized, message, entities, rootCause)
}

• After defining your custom errors, you have to register the function used to transform your custom DomainError to your custom RestAPIError. For example:

package main

import (
	"net/http"

	"github.com/anhvietnguyennva/go-error/pkg/errors"
	"github.com/anhvietnguyennva/go-error/pkg/transformer"
)

const (
	DomainErrCodeCustomized = "DOMAIN:CUSTOMIZED"
	DomainErrMsgCustomized  = "Customized domain error"

	ClientErrCodeCustomized = 40099
	ClientErrMsgCustomized  = "Customized client error"
)

func NewDomainErrCustomized(rootCause error, entities ...string) *errors.DomainError {
	return errors.NewDomainError(DomainErrCodeCustomized, DomainErrMsgCustomized, entities, rootCause)
}

func NewRestAPIErrCustomized(rootCause error, entities ...string) *errors.RestAPIError {
	message := errors.AppendEntitiesToErrMsg(ClientErrMsgCustomized, entities)
	return errors.NewRestAPIError(http.StatusBadRequest, ClientErrCodeCustomized, message, entities, rootCause)
}

func main() {
	t := transformer.RestTransformerInstance()
	t.RegisterTransformFunc(DomainErrCodeCustomized, NewRestAPIErrCustomized)
}

• NOTE:
  • Each error should have a unique error code. Otherwise, it can lead to unexpected results when transforming. So You should not define your custom error code as one of the predefined error codes in "go-error".
  • The ClientErrorCode should contain information about HTTP Status. It makes the error code more meaningful
  • Registering new InfraError is done in a similar way

For gin framework

• This lib provides the function ValidationErrToRestAPIErr(err error) which can be used when binding and validating the request.