ESPWoL/espwol/macsave.ino

void handleSaveMac() {
  if (server.hasArg("mac")) {
    // Extract the string from the POST request
    String data = server.arg("mac");

    // Open the file in write mode
    File file = LittleFS.open(DB_PATH, "w");
    if (!file) {
      server.send(500, "text/plain", "Failed to open file for writing");
      return;
    }

    // Write the string data to the file
    file.print(data);
    file.close();

    sendOK();
  } else {
    server.send(400, "text/plain", "No string provided in the request");
  }
}

void handleGetMac() {
  // Open the file in read mode
  File file = LittleFS.open(DB_PATH, "r");
  if (!file) {
    server.send(500, "text/plain", "Failed to open file for reading");
    return;
  }

  // Read the string data from the file
  String data = file.readString();
  file.close();

  // Send the string data as the json resp
  server.send(200, "application/json", data);
}