API发现自己的URL Golang

Question

I've created an API in Go that can search or directly access an Element via ElasticSearch, which then adds some data to the JSON payload, and returns that to the user. When searching I'm returning a list of Elements, and I'd like to be able to give a direct URL to the specific Element should the user wish to get more information.

However I can't ascertain how the application is supposed to figure out its own URL. In the event that it can't, what would be a reasonable alternative for the URL itself?

Using net/http package and gorilla/mux for net based things.

Answer 1

You can "reverse" a gorilla/mux url by looking up the route by name, and generating the url with Route.URL

You will want to name your route, so that you can easily look it up via Router.Get.

r := mux.NewRouter()
r.HandleFunc("/articles/{category}/{id:[0-9]+}", ArticleHandler).
  Name("article")

And once you have the route, you can build a url by passing the parameters to URL

url, err := r.Get("article").URL("category", "technology", "id", "42")
// "/articles/technology/42"

Note that if you want the host to be inserted automatically, it will need to be defined on your route:

r := mux.NewRouter()
r.Host("{subdomain}.domain.com").
  HandleFunc("/articles/{category}/{id:[0-9]+}", ArticleHandler).
  Name("article")

// url.String() will be "http://news.domain.com/articles/technology/42"
url, err := r.Get("article").URL("subdomain", "news",
                                 "category", "technology",
                                 "id", "42")