I am using a map to store random string keys to *os.File objects. Users will be uploading a file and I want to hold a reference to the file in a global map so I can delete it later.
I have an http handler to process the upload and at the end, I map a random key from the OS uuidgen to "logBundleFile" which is type *os.File.
var db = map[string]*os.File{}
func uploadHandler(w http.ResponseWriter, r *http.Request) {
r.ParseMultipartForm(5 << 30)
file, handler, err := r.FormFile("file")
if err != nil {
log.Fatalf("Error retrieving the file: %v", err)
return
}
defer file.Close()
logBundleFile, err := ioutil.TempFile("", handler.Filename)
if err != nil {
log.Fatal(err)
}
defer logBundleFile.Close()
fileBytes, err := ioutil.ReadAll(file)
if err != nil {
log.Fatalf("Error reading file: %v", err)
}
logBundleFile.Write(fileBytes)
id, err := exec.Command("uuidgen").Output()
idStr := string(id[:])
//id := "1"
if err != nil {
log.Fatal(err)
}
db[idStr] = logBundleFile
log.Printf("ID: %v Type: %T
", idStr, idStr)
log.Printf("val: %v Type: %T
", db[idStr], db[idStr])
http.Redirect(w, r, fmt.Sprintf("/%s", idStr), http.StatusMovedPermanently)
}
Once that is done, you get redirected to this sessionHandler. It will check if the ID in the body is valid, i.e, mapped to a *os.File. The "ok" bool is always returning false.
func sessionHandler(w http.ResponseWriter, r *http.Request) {
vars := mux.Vars(r)
id := vars["id"]
log.Printf("ID: %v Type: %T
", id, id)
log.Printf("val: %v Type: %T
", db[id], db[id])
if val, ok := db[id]; ok {
w.Write([]byte(fmt.Sprintf("Session %s %v", id, val)))
} else {
http.Redirect(w, r, "/", http.StatusMovedPermanently)
}
}
Here is an output from the prints. In the uploadHandler, we can see that we have a string key mapped to a non-nil *os.File.
But in the session handler, the same string key maps to a nil *os.File. I don't know what is going on.
2019/08/27 19:49:49 ID: BA06C157-451E-48B5-85F9-8069D9A4EFCE
Type: string
2019/08/27 19:49:49 val: &{0xc000160120} Type: *os.File
2019/08/27 19:49:49 ID: BA06C157-451E-48B5-85F9-8069D9A4EFCE Type: string
2019/08/27 19:49:49 val: <nil> Type: *os.File
