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\esp320円.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\esp320円.1.1\libraries\FS 
 Using library WiFi at version 1.0 in folder: C:\..\Arduino15\packages\firebeetle32\hardware\esp320円.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.

• Xenoshell: hello @timemage thanks for your very detailed answer. I got the code to compile too, but when i tried to connect to the wifi from the ESP the IP adress is not reachable. The output i get from serial monitor is " dhcps: send_offer>>udp_sendto result 0 ". Do you maybe know what could be the problem?
• timemage: As of yet, I don't have an ESP32 board, so I have no way of troubleshooting this. What you're asking about seems like an entirely new question. I would say cut down your program to the minimal thing necessary to demonstrate the problem. Given the message you're quoting, your demo program should not have #include "ESPAsyncWebServer.h" or #include "AsyncTCP.h" in it at all. If you don't find the problem in the course of making the demo, post it as part of a new question.
• Xenoshell: Ok still thanks for your answers, right now i settle on the version that works and if i have enough time i will come back to this problem
• Sun Bee: Thank you! This is a very helpful answer with expert analysis.