golang中字段的界面

Question

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

Answer 1

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 uploadResult
  ul.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.