Custom error struct for Go apps

errorsx.go

package errorsx

import (
	"errors"
	"fmt"
	"net/http"
)

type AppError struct {
	message    string
	code       int
	statusCode int
	internal   bool
}

func (e *AppError) Code() int {
	return e.code
}

func (e *AppError) Message() string {
	return e.message
}

func (e *AppError) StatusCode() int {
	return e.statusCode
}

func (e *AppError) Internal() bool {
	return e.internal
}

func (e *AppError) Error() string {
	return fmt.Sprintf(`[%d] %s (internal=%t)`, e.code, e.message, e.internal)
}

func New() *AppError {
	return &AppError{
		code:       http.StatusOK,
		message:    http.StatusText(http.StatusOK),
		statusCode: http.StatusOK,
		internal:   false,
	}
}

func (e *AppError) WithCode(code int) *AppError {
	e.code = code
	return e
}

func (e *AppError) WithStatusCode(statusCode int) *AppError {
	e.statusCode = statusCode
	return e
}

func (e *AppError) WithMessage(message string) *AppError {
	e.message = message
	return e
}

func (e *AppError) WithInternal() *AppError {
	e.internal = true
	return e
}

func As(err error) (*AppError, bool) {
	var errX *AppError
	ok := errors.As(err, &errX)
	if errX == nil {
		return nil, false
	}
	return errX, ok
}