当业务需要更复杂的错误码定义时，我们可以自定义实现业务自己的错误码，只需要实现​gcode.Code​相关的接口即可。

我们来看个例子。

自定义错误码

定义结构体并实现​gcode.code​接口定义的方法

type BizCode struct {
	code    int
	message string
	detail  BizCodeDetail
}
type BizCodeDetail struct {
	Code     string
	HttpCode int
}

func (c BizCode) BizDetail() BizCodeDetail {
	return c.detail
}

func (c BizCode) Code() int {
	return c.code
}

func (c BizCode) Message() string {
	return c.message
}

func (c BizCode) Detail() interface{} {
	return c.detail
}

func New(httpCode int, code string, message string) gcode.Code {
	return BizCode{
		code:    0,
		message: message,
		detail: BizCodeDetail{
			Code:     code,
			HttpCode: httpCode,
		},
	}
}

定义业务错误码

var (
	CodeNil      = New(200, "OK", "")
	CodeNotFound = New(404, "Not Found", "Resource does not exist")
	CodeInternal = New(500, "Internal Error", "An error occurred internally")
	// ...
)

使用到中间件

func ResponseHandler(r *ghttp.Request) {
	r.Middleware.Next()
	// There's custom buffer content, it then exits current handler.
	if r.Response.BufferLength() > 0 {
		return
	}
	res, err := r.GetHandlerResponse()
	code := gerror.Code(err)
	if code == gcode.CodeNil && err != nil {
		code = CodeInternal
	} else {
		code = CodeNil
	}
	if bizCode, ok := code.(BizCode); ok {
		r.Response.WriteStatus(bizCode.BizDetail().HttpCode)
	}
	_ = r.Response.WriteJson(g.Map{
		`code`:    gcode.CodeOK.Code(),
		`message`: gcode.CodeOK.Message(),
		`data`:    res,
	})
}