英文:
interface for fields in golang
问题
假设我有一个用作上传结果的结构体：
type uploadResult struct {Filename string `json:"filename"`Code string `json:"code"`Reason string `json:"reason"`}
还会有其他类似的结构体，它们都有一个名为Code和另一个名为Reason的字段。因此，有一个类似于公共接口的东西会很有意思（伪代码；这个是无法工作的）：
type apiResult interface {GetCode() stringGetReason() string}
因为我想调用一个函数来提取一些公共字段，但只提取那些公共字段：
func failExit(result apiResult) {fmt.Println(result.GetReason())}
那么，我应该如何重写它以达到我期望的效果呢？
最好的问候。
英文:
Let's say I have a struct which should be used as a result for an upload:
type uploadResult struct {Filename string `json:"filename"`Code string `json:"code"`Reason string `json:"reason"`}
There will be other structs like this one, both having a field Code and another one called Reason. It would therefore be interesting to have something like a common interface (pseudo-go-code; this one doesn't work):
type apiResult interface {Code string `json:"code"`Reason string `json:"reason"`}
Because I would like to call a function which extracts some common fields, but only those that are common:
func failExit(result apiResult) {fmt.Println(result.Reason)}
So how would I rewrite it so that it does what I'm expecting?
Best regards
答案1
得分: 11
你只需要在特定的结构体中嵌入具有共同字段的结构体即可。
type apiResult struct {Code string `json:"code"`Reason string `json:"reason"`}func failExit(result apiResult) {fmt.Println(result.Reason)}type uploadResult struct {Filename string `json:"filename"`apiResult // <-- 嵌入}func main() {var ul uploadResultul.Code = "...一些代码..."ul.Reason = "描述"ul.Filename = "foo.txt"failExit(ul.apiResult)}
所以在这种情况下，实际上不需要使用接口。只需将apiResult嵌入到需要它的结构体中即可。
英文:
You should just be able to embed a struct with the common fields in the specific structs.
Live demo: http://play.golang.org/p/7Ju-r-yE1-
type apiResult struct {Code string `json:"code"`Reason string `json:"reason"`}func failExit(result apiResult) {fmt.Println(result.Reason)}type uploadResult struct {Filename string `json:"filename"`apiResult // <-- embedded}func main() {var ul uploadResultul.Code = "...some code..."ul.Reason = "The description"ul.Filename = "foo.txt"failExit(ul.apiResult)}
So there shouldn't really be any need for interfaces in this situation. Just embed the apiResult in whatever structs need it.
答案2
得分: 4
长话短说，Go语言的接口不允许声明字段，因为从概念上讲，它们处理的是行为而不是数据。字段是数据。
有几种方法可以实现你想要做的事情：
以下是一些处理方法的示例：
这个示例使用接口将APIResult字段作为apiResponse接口的一部分公开：
http://play.golang.org/p/ONLzvqlP5R
这个示例使用接口将APIResult作为包含它的任何Result结构的一部分公开：
http://play.golang.org/p/NzxPHhDls_
另外，你可以通过组合来解决这个问题，让APIResponse成为一个包含常见字段的结构体，然后任何需要这些字段的其他结构体都导出APIResponse结构体。
type APIResult struct {Code string `json:"code"`Reason string `json:"reason"`}type UploadResult struct {Filename string `json:"filename"`APIResult}func failExit(result APIResult) {fmt.Println(result.Reason)}
http://play.golang.org/p/k85vTJoFRn
英文:
Long story short, Go interfaces don't allow fields to be declared because conceptually they deal with behavior not data. Fields are data.
There's a couple of ways to go about what you want to do:
Here's some examples on how to approach this:
This one uses an interface to expose the APIResult fields as part of the apiResponse interface:
http://play.golang.org/p/ONLzvqlP5R
This one uses an interface to expose the APIResult as part of any Result struct that contains one:
http://play.golang.org/p/NzxPHhDls_
On that note, you could solve this by using composition by having APIResponse be a struct that has the common fields and then any other struct that needs those fields exports the APIResponse struct.
type APIResult struct {Code string `json:"code"`Reason string `json:"reason"`}type UploadResult struct {Filename string `json:"filename"`APIResult}func failExit(result APIResult) {fmt.Println(result.Reason)}
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