文件存在时，http.FileServer始终为404

Question

Beginner Go Question

I have this directory structure.

app_executable
html
 |
  - index.html
data
 |
  - static_file.json

I can't get it to serve the static_file.json in data/static_file.json.

func main() {
  // this works and serves html/index.html
  html := http.FileServer(http.Dir("html"))
  http.Handle("/", html)

  // this always 404's
  data := http.FileServer(http.Dir("data"))
  http.Handle("/data/", data)

  fmt.Println("Listening on port " + port + "...")
  log.Fatal(http.ListenAndServe(port, nil))
}

Any help is appreciated!

Answer 1

The problem is that the FileServer handler is actually looking for a file on this path:

./data/data/static_file.json

instead of

./data/statif_file.json

If you make the first file exist, your code will work. What you probably want to do is either:

data := http.FileServer(http.Dir("data"))
http.Handle("/", data)

Or

data := http.FileServer(http.Dir("data"))
http.Handle("/data/", http.StripPrefix("/data/", data))

I would opt for the former, as it is probably what you really want to do. Attach the handler to the root, and anything matching /data/ will return as expected.

If you look at what is actually returned from the call to

data := http.FileServer(http.Dir("data"))

You will see it is

&http.fileHandler{root:"data"}

Which is saying the root is at ./data, so try finding a file under that root matching the path of the request. In your case that path is data/static_file.json so ultimately it checks for ./data/data/static_file.json which does not exist and it 404s