GOLANG How can I load a certain html file from templates directory using http.FileServer

Issue

func main() {
    mux := http.NewServeMux()
    staticHandler := http.FileServer(http.Dir("./templates"))
    mux.Handle("/", http.StripPrefix("/", staticHandler))
    log.Fatal(http.ListenAndServe(":8080", mux))
}

I want to load a html file which is in ‘templates’ directory.
if there are more than one files in ‘templates’, how can I select certain file to load?

Solution

You can use http.ServeFile() to build your own file server.

See sketch below.

Then you can intercept the served files within your custom fileHandler.ServeHTTP().

package main

import (
    "log"
    "net/http"
    "path"
    "path/filepath"
    "strings"
)

func main() {
    mux := http.NewServeMux()

    //staticHandler := http.FileServer(http.Dir("./templates"))
    staticHandler := fileServer("./templates")

    mux.Handle("/", http.StripPrefix("/", staticHandler))
    log.Printf("listening")
    log.Fatal(http.ListenAndServe(":8080", mux))
}

// returns custom file server
func fileServer(root string) http.Handler {
    return &fileHandler{root}
}

// custom file server
type fileHandler struct {
    root string
}

func (f *fileHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
    upath := r.URL.Path
    if !strings.HasPrefix(upath, "/") {
        upath = "/" + upath
        r.URL.Path = upath
    }
    name := filepath.Join(f.root, path.Clean(upath))
    log.Printf("fileHandler.ServeHTTP: path=%s", name)
    http.ServeFile(w, r, name)
}

Answered By – Everton

Answer Checked By – Timothy Miller (GoLangFix Admin)

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