ragnar-johannsson/rww

http.ResponseWriter wrapper

ResponseWriter Wrapper

rww is a wrapper for http.ResponseWriter enabling response manipulation based on status codes specified downstream in the middleware chain, as well as getting some basic information about the response being sent out.

Example usage

Logging handler using rww to report final status and response content size:

logger := func(h http.Handler) http.Handler {
    return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
        ww := rww.New(w)

        h.ServeHTTP(ww, r)

        log.Printf(
            "- %s - \"%s %s %s\" %d %d",
            r.RemoteAddr,
            r.Method,
            r.URL.RequestURI(),
            r.Proto,
            ww.Status, // Get both the response status and the
            ww.Size,   // content length from the wrapper
        )
    })
}

helloWorld := func(w http.ResponseWriter, r *http.Request) {
    fmt.Fprintln(w, "Hello world!")
}

http.HandleFunc("/", helloWorld)
http.ListenAndServe(":8080", logger(http.DefaultServeMux))

Redirect handler using rww to handle response based on downstream status:

redirector := func(h http.Handler) http.Handler {
    return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
        ww := rww.New(w)
        u, _ := url.Parse("http://other.host/")
        u.Path = r.URL.EscapedPath()

        ww.AddIntercept(
            // Expected status code
            http.StatusNotFound,
            // Intended status code
            http.StatusTemporaryRedirect,
            // Injected http.ResponseWriter.Write() func
            nil,
            // Headers to add to the response
            map[string]string{
                "Location": u.String(),
            },
        )
    })
}

staticFileHandler := http.FileServer(http.Dir("/path/to/files"))
http.ListenAndServe(":8080", redirector(staticFileHandler))

License

BSD 2-Clause. See the LICENSE file for details.