Golang如何实现自定义错误码

type ErrorCode int

const (
    ErrSuccess ErrorCode = iota
    ErrInvalidParameter
    ErrNotFound
    ErrDatabaseError
    ErrUnauthorized
)

type CustomError struct {
    Code    ErrorCode
    Message string
    Cause   error // 可选：记录原始错误
}

func (e *CustomError) Error() string {
    if e.Cause != nil {
        return fmt.Sprintf("[%d] %s: %v", e.Code, e.Message, e.Cause)
    }
    return fmt.Sprintf("[%d] %s", e.Code, e.Message)
}

func NewInvalidParameter(msg string) error {
    return &CustomError{
        Code:    ErrInvalidParameter,
        Message: msg,
    }
}

func NewNotFound(msg string) error {
    return &CustomError{
        Code:    ErrNotFound,
        Message: msg,
    }
}

func WrapError(code ErrorCode, msg string, err error) error {
    return &CustomError{
        Code:    code,
        Message: msg,
        Cause:   err,
    }
}

if userID <= 0 {
    return nil, NewInvalidParameter("用户ID无效")
}

if err := someFunc(); err != nil {
    if customErr, ok := err.(*CustomError); ok {
        switch customErr.Code {
        case ErrInvalidParameter:
            log.Println("参数错误:", customErr.Message)
        case ErrNotFound:
            log.Println("未找到资源")
        default:
            log.Println("其他错误:", err)
        }
    } else {
        log.Println("未知错误:", err)
    }
}

var customErr *CustomError
if errors.As(err, &customErr) {
    fmt.Printf("错误码: %d, 消息: %s\n", customErr.Code, customErr.Message)
}