go从0到1项目实战体系三十三：service错误接收

三层代码就类似一个中间件,后面还可以扩展为函数式中间件,并且无框架无关.

1. service出错如何接收?

(1). service:

// 返回追加了两个参数
func(this *BookService) getList(req *BookListRequest) (*Models.AdminLoges, error) {
	books := &Models.AdminLoges{}
	// 如果在连接池错误或sql查询时出现错误,或者有逻辑需要判断错误
	err := Init.GetDB().Limit(req.Size).Order("id desc").Find(books).Error
	if err != nil {
		return nil, err
	} else {
		return books, nil
	}
}

func(this *BookService) getDetail(req *BookDetailRequest) (*Models.AdminLogs, error) {
	book := &Models.AdminLogs{}
	// 判断为空
	if Init.GetDB().Find(book, req.Id).RowsAffected != 1 {
		return nil, fmt.Errorf("no record")
	} else {
		return book, nil
	}
}

(2). endpoint:

func BookListEndpoint(book *BookService) Lib.Endpoint {
	return func(ctx *gin.Context, request interface{}) (interface{}, error) {
		req := request.(*BookListRequest)
		// 这里改为两个值接收
		result, err := book.getList(req)
		return &BookListResponse{Result: result}, err  // 将err返回出去
	}
}

func BookDetailEndpoint(book *BookService) Lib.Endpoint {
	return func(ctx *gin.Context, request interface{}) (interface{}, error) {
		req := request.(*BookDetailRequest)
		result, err := book.getDetail(req)
		return &BookDetailResponse{Result: result}, err
	}
}

---

2. panic错误处理:

(1). service:

func(this *BookService) getList(req *BookListRequest) (*Models.AdminLoges, error) {
	panic("出错了")
	books := &Models.AdminLoges{}
	......
}

(2). serviceHelp:

func RegisterHandler(encodeFunc EncodeRequestFunc, endpoint Endpoint, decodeFunc DecodeResponseFunc) func (ctx *gin.Context) {
	return func(ctx *gin.Context) {
		// 捕获panic错误,这里也可以优化,不写在这里,可以写在外部,使用装饰器的方式加进来
		defer func() {
			if r := recover(); r != nil {
				ctx.JSON(500, gin.H{"error": fmt.Sprintf("fatal error:%s", r)})
				return
			}
		}()
		// 获取参数
		request, err := encodeFunc(ctx)
		......
	}
}