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package middleware
import (
"context"
"net/http"
"strings"
"github.com/go-chi/chi"
)
var (
// URLFormatCtxKey is the context.Context key to store the URL format data
// for a request.
URLFormatCtxKey = &contextKey{"URLFormat"}
)
// URLFormat is a middleware that parses the url extension from a request path and stores it
// on the context as a string under the key `middleware.URLFormatCtxKey`. The middleware will
// trim the suffix from the routing path and continue routing.
//
// Routers should not include a url parameter for the suffix when using this middleware.
//
// Sample usage.. for url paths: `/articles/1`, `/articles/1.json` and `/articles/1.xml`
//
// func routes() http.Handler {
// r := chi.NewRouter()
// r.Use(middleware.URLFormat)
//
// r.Get("/articles/{id}", ListArticles)
//
// return r
// }
//
// func ListArticles(w http.ResponseWriter, r *http.Request) {
// urlFormat, _ := r.Context().Value(middleware.URLFormatCtxKey).(string)
//
// switch urlFormat {
// case "json":
// render.JSON(w, r, articles)
// case "xml:"
// render.XML(w, r, articles)
// default:
// render.JSON(w, r, articles)
// }
// }
//
func URLFormat(next http.Handler) http.Handler {
fn := func(w http.ResponseWriter, r *http.Request) {
ctx := r.Context()
var format string
path := r.URL.Path
if strings.Index(path, ".") > 0 {
base := strings.LastIndex(path, "/")
idx := strings.LastIndex(path[base:], ".")
if idx > 0 {
idx += base
format = path[idx+1:]
rctx := chi.RouteContext(r.Context())
rctx.RoutePath = path[:idx]
}
}
r = r.WithContext(context.WithValue(ctx, URLFormatCtxKey, format))
next.ServeHTTP(w, r)
}
return http.HandlerFunc(fn)
}
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