HTTP_GET not clarified in scope

Question

I'm trying to do an async webserver with access point using an ESP32.

It's a little bit of a mix between This tutorial for AP and async and this tutorial since it's also with an async webserver and it uses inputs which I desperately need.

The part I don't understand is I included all the necessary libraries and I still got this error. If I copy-paste the code in one block everything is fine. It was never necessary to declare HTTP_GET since it should be a variable from a library.

So what's wrong?

These are my errors:

    In file included from C:\..\Arduino\libraries\ESPAsyncWebServer-master\src/ESPAsyncWebServer.h:467:0,
                     from C:\..\AppData\Local\Temp\arduino_build_497972\sketch\webserver.h:5,
                     from C:\..\Async Webserver ESP32\main\main.ino:3:
    C:\..\Arduino\libraries\ESPAsyncWebServer-master\src/WebHandlerImpl.h: In constructor 'AsyncCallbackWebHandler::AsyncCallbackWebHandler()':
    C:\..\Arduino\libraries\ESPAsyncWebServer-master\src/WebHandlerImpl.h:76:49: error: 'HTTP_ANY' was not declared in this scope
         AsyncCallbackWebHandler() : _uri(), _method(HTTP_ANY), _onRequest(NULL), _onUpload(NULL), _onBody(NULL), _isRegex(false) {}
                                                     ^
    In file included from C:\..\Arduino\libraries\ESPAsyncWebServer-master\src/ESPAsyncWebServer.h:467:0,
                     from C:\..\AppData\Local\Temp\arduino_build_497972\sketch\webserver.h:5,
                     from C:\..\AppData\Local\Temp\arduino_build_497972\sketch\webserver.cpp:1:
    C:\..\Arduino\libraries\ESPAsyncWebServer-master\src/WebHandlerImpl.h: In constructor 'AsyncCallbackWebHandler::AsyncCallbackWebHandler()':
    C:\..\Arduino\libraries\ESPAsyncWebServer-master\src/WebHandlerImpl.h:76:49: error: 'HTTP_ANY' was not declared in this scope
         AsyncCallbackWebHandler() : _uri(), _method(HTTP_ANY), _onRequest(NULL), _onUpload(NULL), _onBody(NULL), _isRegex(false) {}
                                                     ^
    C:\Users\Valentin\AppData\Local\Temp\arduino_build_497972\sketch\webserver.cpp: In function 'void setup_server(AsyncWebServer)':
    webserver.cpp:6:18: error: 'HTTP_GET' was not declared in this scope
       server.on("/", HTTP_GET, [](AsyncWebServerRequest * request) {
                      ^
    Multiple libraries were found for "WiFi.h"
     Used: C:\..\Arduino15\packages\firebeetle32\hardware\esp32\0.1.1\libraries\WiFi
     Not used: C:\Program Files (x86)\Arduino\libraries\WiFi
    Using library ESPAsyncWebServer-master at version 1.2.3 in folder: C:\..\Arduino\libraries\ESPAsyncWebServer-master 
    Using library FS at version 1.0 in folder: C:\..\Arduino15\packages\firebeetle32\hardware\esp32\0.1.1\libraries\FS 
    Using library WiFi at version 1.0 in folder: C:\..\Arduino15\packages\firebeetle32\hardware\esp32\0.1.1\libraries\WiFi 
    Using library AsyncTCP-master at version 1.1.1 in folder: C:\..\Arduino\libraries\AsyncTCP-master 
    exit status 1
    'HTTP_GET' was not declared in this scope

I already tried to use the standard Arduino WiFi library which resulted just in more errors so I switched it back.

I split up the code into three pieces for better visibility.

main.ino

#include <Arduino.h>
#include "webserver.h"
    
// REPLACE WITH YOUR NETWORK CREDENTIALS
const char* ssid = "blabla";
const char* password = "blabla";
    
void setup() {
  Serial.begin(115200);
  WiFi.softAP(ssid, password);
  IP = WiFi.softAPIP();
    
  Serial.println();
  Serial.print("IP Address: ");
  Serial.println(IP);
      
  setup_server(server);
}

void loop() {}

webserver.cpp

#include "webserver.h"
    
void setup_server(AsyncWebServer server) {
  // Send web page with input fields to client
  server.on("/", HTTP_GET, [](AsyncWebServerRequest * request) {
    request->send_P(200, "text/html", index_html);
  });
    
  // Send a GET request to <ESP_IP>/get?input1=<inputMessage>
  server.on("/get", HTTP_GET, [] (AsyncWebServerRequest * request) {
    // GET input1 value on <ESP_IP>/get?input1=<inputMessage>
    if (request->hasParam(PARAM_INPUT_1)) {
      inputMessage = request->getParam(PARAM_INPUT_1)->value();
      inputParam = PARAM_INPUT_1;
    }
    // GET input2 value on <ESP_IP>/get?input2=<inputMessage>
    else if (request->hasParam(PARAM_INPUT_2)) {
      inputMessage = request->getParam(PARAM_INPUT_2)->value();
      inputParam = PARAM_INPUT_2;
    }
    // GET input3 value on <ESP_IP>/get?input3=<inputMessage>
    else if (request->hasParam(PARAM_INPUT_3)) {
      inputMessage = request->getParam(PARAM_INPUT_3)->value();
      inputParam = PARAM_INPUT_3;
    }
    else {
      inputMessage = "No message sent";
      inputParam = "none";
    }
    Serial.println(inputMessage);
    request->send(200, "text/html", "HTTP GET request sent to your ESP on input field ("
      + inputParam + ") with value: " + inputMessage +
      "<br><a href=\"/\">Return to Home Page</a>");
    });
    server.onNotFound(notFound);
    server.begin();
  }
    
void notFound(AsyncWebServerRequest *request) {
  request->send(404, "text/plain", "Not found");
}

webserver.h

#ifndef WEBSERVER_H
#define WEBSERVER_H
    
#include "Arduino.h"
#include "ESPAsyncWebServer.h"
#include "AsyncTCP.h"
#include <WiFi.h>
    
const char* PARAM_INPUT_1 = "input1";
const char* PARAM_INPUT_2 = "input2";
const char* PARAM_INPUT_3 = "input3";
  
AsyncWebServer server(80);
    
String music_state;
IPAddress IP;
    
String inputMessage;
String inputParam;
    
// HTML web page to handle 3 input fields (input1, input2, input3)
const char index_html[] PROGMEM = R"rawliteral(
<!DOCTYPE HTML><html><head>
  <title>ESP Input Form</title>
  <meta name="viewport" content="width=device-width, initial-scale=1">
  </head><body>
  <form action="/get">
    input1: <input type="text" name="input1">
    <input type="submit" value="Submit">
  </form><br>
  <form action="/get">
    input2: <input type="text" name="input2">
    <input type="submit" value="Submit">
  </form><br>
  <form action="/get">
    input3: <input type="text" name="input3">
    <input type="submit" value="Submit">
  </form>
</body></html>)rawliteral";

void setup_server(AsyncWebServer server);
    
void notFound(AsyncWebServerRequest *request);
    
#endif

Thanks for the input, I will check back tomorrow and answer all questions and test every suggestion.

Answer 1

Macro Conflict

You have two basic problems here. The more significant one is that your use of SERVER_H in your include guard:

#ifndef WEBSERVER_H
#define WEBSERVER_H

conflicts with a usage in ESPAsyncWebServer.h:

#ifndef WEBSERVER_H
typedef enum {
  HTTP_GET     = 0b00000001,
  HTTP_POST    = 0b00000010,
  HTTP_DELETE  = 0b00000100,
  HTTP_PUT     = 0b00001000,
  HTTP_PATCH   = 0b00010000,
  HTTP_HEAD    = 0b00100000,
  HTTP_OPTIONS = 0b01000000,
  HTTP_ANY     = 0b01111111,
} WebRequestMethod;
#endif

and that explains why your HTTP_GET etc are not found. They're not being defined because of your include guard macro.

Changing your code to:

#ifndef XENOSHELL_WEBSERVER_H
#define XENOSHELL_WEBSERVER_H

or something similar will get you past that problem.

Multiply Defined Variables

You also have some non-static variables defined in your webserver.h that will also need to be changed somehow. A simple change just being to make them static:

static const char* PARAM_INPUT_1 = "input1";
static const char* PARAM_INPUT_2 = "input2";
static const char* PARAM_INPUT_3 = "input3";

IPAddress IP; is only used in main.ino, and should be moved there as a local const IPAddress IP = WiFi.softAPIP(); If you leave it in the header you'll get multiple definitions because of that.

String inputMessage; and String inputParam; Same problem, only these belong inside your lambda expression in server.on("/get", HTTP_GET, [] (AsyncWebServerRequest * request) {

I don't know why your server variable is in the header either. The simplest thing to do is put it in webserver.cpp instead and don't pass it in to setup_server, in other word remove the parameter and use the variable defined in the same file as the function.

---

Having done that your code compiles fine. Whether or not it works is another question. I am unable to test that.