Class event calling

Projects Programming
1

I have a problem with the onEvent function from the WebSocketClient lib. Here is my code and my error message.

header:

[
#ifndef Lamp_Alexa_h
#define Lamp_Alexa_h

// including Amazon Alexa necessary libaries
#include <WebSocketsClient.h> // get it from https://github.com/Links2004/arduinoWebSockets/releases 
#include <ArduinoJson.h> // get it from https://arduinojson.org/ or install via Arduino library manager
#include <StreamString.h>

// define parameters for sinric
#define API_ENDPOINT "http://sinric.com"
#define HEARTBEAT_INTERVAL 300000 // 5 Minutes


class Lamp_Alexa{
  public:
    Lamp_Alexa(String apiKey, String deviceId);
    void turnOn();
    void turnOff();
    void init();
  private:
    WebSocketsClient webSocket;
    String state;
    void webSocketEvent(WStype_t type, uint8_t * payload, size_t length);
    String _deviceId;
    String _apiKey;
    bool isConnected;
};

#endif

cpp:

#include "Lamp_Alexa.h"

Lamp_Alexa::Lamp_Alexa(String apiKey, String deviceId){
  _deviceId = deviceId;
  _apiKey = apiKey;
}

void Lamp_Alexa::init(){
  // server address, port and URL
  webSocket.begin("iot.sinric.com", 80, "/");

  // event handler
  webSocket.onEvent(this->webSocketEvent);
  webSocket.setAuthorization("apikey", _apiKey);
  
  // try again every 5000ms if connection has failed
  webSocket.setReconnectInterval(5000);
}

void Lamp_Alexa::webSocketEvent(WStype_t type, uint8_t * payload, size_t length){
  switch(type) {
    case WStype_DISCONNECTED:
      isConnected = false;    
      Serial.printf("[WSc] Webservice disconnected from sinric.com!\n");
      break;
    case WStype_CONNECTED: {
      isConnected = true;
      Serial.printf("[WSc] Service connected to sinric.com at url: %s\n", payload);
      Serial.printf("Waiting for commands from sinric.com ...\n");        
      }
      break;
    case WStype_TEXT: {
        Serial.printf("[WSc] get text: %s\n", payload);
                
        DynamicJsonBuffer jsonBuffer;
        JsonObject& json = jsonBuffer.parseObject((char*)payload); 
        String deviceId = json ["deviceId"];     
        String action = json ["action"];
        
        if(action == "setPowerState") { // Switch or Light
            String value = json ["value"];
            if(value == "ON") {
                ;
            } else {
                ;
            }
        }
        else if(action == "SetColor") {
            // Alexa, set the device name to red (0) / green (120) / blue (240)
            // get text: {"deviceId":"xxxx","action":"SetColor","value":{"hue":0,"saturation":1,"brightness":1}}
            String hue = json ["value"]["hue"];
            String saturation = json ["value"]["saturation"];
            String brightness = json ["value"]["brightness"];

            Serial.println("[WSc] hue: " + hue);
            Serial.println("[WSc] saturation: " + saturation);
            Serial.println("[WSc] brightness: " + brightness);

            if(hue == "0"){
              ;
            }
            else if(hue == "120"){
              ;
            }
            else if(hue == "240"){
              ;
            }
        }// end SetColor
        
        else if(action == "setBrightness") {
          ;
        }// end brightness
        
        else if(action == "AdjustBrightness") {
          ;
        }
        
        else if (action == "test") {
            Serial.println("[WSc] received test command from sinric.com");
        }
      }
      break;
    case WStype_BIN:
      Serial.printf("[WSc] get binary length: %u\n", length);
      break;
  } 
}

error message:

C:\Users\xanix\AppData\Local\Temp\arduino_build_362415\sketch\Lamp_Alexa.cpp: In member function 'void Lamp_Alexa::init()':

Lamp_Alexa.cpp:13: error: no matching function for call to 'WebSocketsClient::onEvent(<unresolved overloaded function type>)'

   webSocket.onEvent(this->webSocketEvent);

                                         ^

C:\Users\xanix\AppData\Local\Temp\arduino_build_362415\sketch\Lamp_Alexa.cpp:13:41: note: candidate is:

In file included from C:\Users\xanix\AppData\Local\Temp\arduino_build_362415\sketch\Lamp_Alexa.h:11:0,

                 from C:\Users\xanix\AppData\Local\Temp\arduino_build_362415\sketch\Lamp_Alexa.cpp:1:

C:\Users\xanix\Documents\Arduino\libraries\arduinoWebSockets-2.1.1\src/WebSocketsClient.h:66:14: note: void WebSocketsClient::onEvent(WebSocketsClient::WebSocketClientEvent)

         void onEvent(WebSocketClientEvent cbEvent);

              ^

C:\Users\xanix\Documents\Arduino\libraries\arduinoWebSockets-2.1.1\src/WebSocketsClient.h:66:14: note:   no known conversion for argument 1 from '<unresolved overloaded function type>' to 'WebSocketsClient::WebSocketClientEvent {aka std::function<void(WStype_t, unsigned char*, unsigned int)>}'

Lamp_Alexa.cpp:14: error: no matching function for call to 'WebSocketsClient::setAuthorization(const char [7], String&)'

   webSocket.setAuthorization("apikey", _apiKey);

                                               ^

C:\Users\xanix\AppData\Local\Temp\arduino_build_362415\sketch\Lamp_Alexa.cpp:14:47: note: candidates are:

In file included from C:\Users\xanix\AppData\Local\Temp\arduino_build_362415\sketch\Lamp_Alexa.h:11:0,

                 from C:\Users\xanix\AppData\Local\Temp\arduino_build_362415\sketch\Lamp_Alexa.cpp:1:

C:\Users\xanix\Documents\Arduino\libraries\arduinoWebSockets-2.1.1\src/WebSocketsClient.h:82:14: note: void WebSocketsClient::setAuthorization(const char*, const char*)

         void setAuthorization(const char * user, const char * password);

              ^

C:\Users\xanix\Documents\Arduino\libraries\arduinoWebSockets-2.1.1\src/WebSocketsClient.h:82:14: note:   no known conversion for argument 2 from 'String' to 'const char*'

C:\Users\xanix\Documents\Arduino\libraries\arduinoWebSockets-2.1.1\src/WebSocketsClient.h:83:14: note: void WebSocketsClient::setAuthorization(const char*)

         void setAuthorization(const char * auth);

              ^

C:\Users\xanix\Documents\Arduino\libraries\arduinoWebSockets-2.1.1\src/WebSocketsClient.h:83:14: note:   candidate expects 1 argument, 2 provided

Bibliothek arduinoWebSockets-2.1.1 in Version 2.1.1 im Ordner: C:\Users\xanix\Documents\Arduino\libraries\arduinoWebSockets-2.1.1  wird verwendet
Bibliothek ESP8266WiFi in Version 1.0 im Ordner: C:\Users\xanix\AppData\Local\Arduino15\packages\esp8266\hardware\esp8266\2.4.1\libraries\ESP8266WiFi  wird verwendet
Bibliothek ArduinoJson in Version 5.13.2 im Ordner: C:\Users\xanix\Documents\Arduino\libraries\ArduinoJson  wird verwendet
Bibliothek Adafruit_NeoPixel in Version 1.1.6 im Ordner: C:\Users\xanix\Documents\Arduino\libraries\Adafruit_NeoPixel  wird verwendet
Bibliothek Hash in Version 1.0 im Ordner: C:\Users\xanix\AppData\Local\Arduino15\packages\esp8266\hardware\esp8266\2.4.1\libraries\Hash  wird verwendet
exit status 1
no matching function for call to 'WebSocketsClient::onEvent(<unresolved overloaded function type>)'
2

Not a bootloader problem!

3 
void webSocketEvent(WStype_t type, uint8_t * payload, size_t length);

This is not a free function. It is a member function, so the first parameter is always a pointer to the instance. This means that it doesn't match the signature of the callback you're trying to assign it to.

Either make it static, or use std::bind. In the latter case, you have to be very careful that the lifetime of the websocket instance doesn't exceed the lifetime of the callback instance.

Pieter

4

Sorry but i dont get it. I'm just a newbie writing classes and i cant follow you 100%.

I changed it to a static void: static void Lamp_Alexa::webSocketEvent(WStype_t type, uint8_t * payload, size_t length) and it seem it worked but now i've got a new error message.

error message:

sketch\Lamp_Alexa.cpp: In member function 'void Lamp_Alexa::init()':

Lamp_Alexa.cpp:14: error: no matching function for call to 'WebSocketsClient::setAuthorization(const char [7], String&)'

   webSocket.setAuthorization("apikey", _apiKey);

                                               ^

sketch\Lamp_Alexa.cpp:14:47: note: candidates are:

In file included from sketch\Lamp_Alexa.h:11:0,

                 from sketch\Lamp_Alexa.cpp:1:

C:\Users\xanix\Documents\Arduino\libraries\WebSockets\src/WebSocketsClient.h:81:14: note: void WebSocketsClient::setAuthorization(const char*, const char*)

         void setAuthorization(const char * user, const char * password);

              ^

C:\Users\xanix\Documents\Arduino\libraries\WebSockets\src/WebSocketsClient.h:81:14: note:   no known conversion for argument 2 from 'String' to 'const char*'

C:\Users\xanix\Documents\Arduino\libraries\WebSockets\src/WebSocketsClient.h:82:14: note: void WebSocketsClient::setAuthorization(const char*)

         void setAuthorization(const char * auth);

              ^

C:\Users\xanix\Documents\Arduino\libraries\WebSockets\src/WebSocketsClient.h:82:14: note:   candidate expects 1 argument, 2 provided

sketch\Lamp_Alexa.cpp: At global scope:

Lamp_Alexa.cpp:20: error: cannot declare member function 'static void Lamp_Alexa::webSocketEvent(WStype_t, uint8_t*, size_t)' to have static linkage [-fpermissive]

 static void Lamp_Alexa::webSocketEvent(WStype_t type, uint8_t * payload, size_t length){

                                                                                       ^

In file included from sketch\Lamp_Alexa.cpp:1:0:

sketch\Lamp_Alexa.h: In static member function 'static void Lamp_Alexa::webSocketEvent(WStype_t, uint8_t*, size_t)':

Lamp_Alexa.h:32: error: invalid use of member 'Lamp_Alexa::isConnected' in static member function

     bool isConnected;

          ^

Lamp_Alexa.cpp:23: error: from this location

       isConnected = false;    

       ^

In file included from sketch\Lamp_Alexa.cpp:1:0:

Lamp_Alexa.h:32: error: invalid use of member 'Lamp_Alexa::isConnected' in static member function

     bool isConnected;

          ^

Lamp_Alexa.cpp:27: error: from this location

       isConnected = true;

       ^

exit status 1
no matching function for call to 'WebSocketsClient::setAuthorization(const char [7], String&)'

in this section:

void Lamp_Alexa::init(){
  // server address, port and URL
  webSocket.begin("iot.sinric.com", 80, "/");

  // event handler
  webSocket.onEvent(this->webSocketEvent);
  webSocket.setAuthorization("apikey", _apiKey);
  
  // try again every 5000ms if connection has failed
  webSocket.setReconnectInterval(5000);
}
5 
webSocket.setAuthorization("apikey", _apiKey);

Why is _apiKey a String? Just change it to a const char *. I find it very unlikely that your username is "apikey", but I could be wrong, I've never used Alexa.

webSocket.onEvent(this->webSocketEvent);

Not sure if that compiles or not, but even if it does, it doesn't reflect what you're doing. Don't call static class methods from an instance pointer.

6

Going back to your original issue - if making the method static isn't an option because it's interacting with instance-scoped data/methods/variables, i believe this is the syntax to handle calling a member function as the handler for WebSocketClient::onEvent. (I'm away from my full dev environment ATM and not able to 100% verify)

webSocket.onEvent([&](WStype_t t, uint8_t * p, size_t l) {
    webSocketEvent(t, p, l);
  });

Where webSocket is your instance of WebSocketClient, and webSocketEvent() is an instance method of your class (presumably Lamp::Alexa) with the proper signature that WebSocketClientEvent expects. Basically what you're doing here is popping an anonymous function into existence, and
delegating to your other instance method.

Good Luck.