Error: expected initializer before '.' token //

Other Hardware Sensors
1

Hi friends. First of all my first language is not English, excuse me if my spelling is not correct.
I am working in a LoRa network, sending data from a GP2Y1010AU0F sensor from a node to a master and then upload it to ThinkSpeak, in the code of my node I have no problems since it works correctly for me, the detail is in the master's code, at compile time I get an error saying: // expected initializer before '.' token // this error is in variables. Please give me your kind help to find a solution to my problem.

master code:

//ESP32 LoRa Gateway Code//
//En el siguiente código, realice cambios en el SSID WiFi, la contraseña y la clave API de Thingspeak//

#include <WiFi.h>
 
//Libraries for LoRa
#include <SPI.h>
#include <LoRa.h>
 
//define the pins used by the LoRa transceiver module
#define SCLK 5
#define MISO 19
#define MOSI 27
#define CS 18
#define RST 23
#define DIO 26
 
#define BAND 915E6    //433E6 for Asia, 866E6 for Europe, 915E6 for North America
 
 
// Replace with your network credentials
String apiKey = "AIA0FNJK6MGO"; // Enter your Write API key from ThingSpeak
const char *ssid = "Claro_657E94"; // replace with your wifi ssid and wpa2 key
const char *password = "Q7K7X3J2";
const char* server = "api.thingspeak.com";
 
WiFiClient client;
 
 
//Inicializar variables para obtener y guardar datos de LoRa
int rssi;
String loRaMessage;
String dustSensor.getDustDensity();
String dustSensor.getRunningAverage();
String readingID;
 
 
// Reemplaza el marcador de posición con valores GP2Y1010AU0F
  String processor(const String& var){
//Serial.println(var);
  if(var == "DENSIDAD DE POLVO")
  {
    return dustSensor.getDustDensity();
  }
  else if(var == "PROMEDIO")
  {
    return dustSensor.getRunningAverage();
  }
  else if (var == "RSSI")
  {
    return String(rssi);
  }
  return String();
}
 
  void setup() {
  Serial.begin(115200);
  int counter;
 
  //setup LoRa transceiver module
  LoRa.setPins(CS, RST, DIO); //setup LoRa transceiver module
 
  while (!LoRa.begin(BAND) && counter < 10) {
    Serial.print(".");
    counter++;
    delay(2000);
  }
  if (counter == 10) {
    // Increment readingID on every new reading
    Serial.println("Starting LoRa failed!"); 
  }
  Serial.println("LoRa Initialization OK!");
  delay(2000);
 
  // Connect to Wi-Fi network with SSID and password
  Serial.print("Connecting to ");
  Serial.println(ssid);
  WiFi.begin(ssid, password);
  while (WiFi.status() != WL_CONNECTED) {
    delay(2000);
    Serial.print(".");
  }
  // Print local IP address and start web server
  Serial.println("");
  Serial.println("WiFi connected.");
  Serial.println("IP address: ");
  Serial.println(WiFi.localIP());
}
 
 
// Read LoRa packet and get the sensor readings
void loop() 
{
  int packetSize = LoRa.parsePacket();
  if (packetSize)
  {
    Serial.print("Lora packet received: ");
    while (LoRa.available())    // Read packet
  {
    String LoRaData = LoRa.readString();
    Serial.print(LoRaData); 
    
    
    int pos1 = LoRaData.indexOf('/');   
    int pos2 = LoRaData.indexOf('&');   
    readingID = LoRaData.substring(0, pos1);                                          // Obtener readingID
    dustSensor.getDustDensity() = LoRaData.substring(pos1 +1, pos2);                  // Obtener densidad de polvo
    dustSensor.getRunningAverage() = LoRaData.substring(pos2+1, LoRaData.length());   // Obtener PROMEDIO
  }
  
  rssi = LoRa.packetRssi();                                                           // Obtener RSSI
  Serial.print(" with RSSI ");    
  Serial.println(rssi);
}
 
  
  if (client.connect(server, 80)) // "184.106.153.149" or api.thingspeak.com
   {
      String postStr = apiKey;
      postStr += "&field1=";
      postStr += String(readingID);
      postStr += "&field2=";
      postStr += String(dustSensor.getDustDensity());
      postStr += "&field3=";
      postStr += String(dustSensor.getRunningAverage());
      postStr += "&field4=";
      postStr += String(rssi);
      postStr += "\r\n\r\n\r\n\r\n";
    
      client.print("POST /update HTTP/1.1\n");
      client.print("Host: api.thingspeak.com\n");
      client.print("Connection: close\n");
      client.print("X-THINGSPEAKAPIKEY: " + apiKey + "\n");
      client.print("Content-Type: application/x-www-form-urlencoded\n");
      client.print("Content-Length: ");
      client.print(postStr.length());
      client.print("\n\n");
      client.print(postStr);
 
    }    
    //delay(30000);
    }

Sensor node:

//Libraria para LoRa
#include <SPI.h>
#include <LoRa.h>

//Libreria y declaracion de pines para sensor de Polvo
#include <GP2YDustSensor.h>

const uint8_t SHARP_LED_PIN = 12;   //Sharp Dust/particle sensor Led Pin
const uint8_t SHARP_VO_PIN = 36;    //Sharp Dust/particle analog out pin used for reading 

GP2YDustSensor dustSensor(GP2YDustSensorType::GP2Y1010AU0F, SHARP_LED_PIN, SHARP_VO_PIN);
 
//Libraria para la pantalla Oled
#include <U8g2lib.h>
U8G2_SSD1306_128X32_UNIVISION_F_HW_I2C u8g2(U8G2_R0);
 
//define the pins used by the LoRa transceiver module
#define SCLK 5
#define MISO 19
#define MOSI 27
#define CS 18
#define RST 23
#define DIO 26
 
#define BAND 915E6    //433E6 for Asia, 866E6 for Europe, 915E6 for North America
 
//packet counter
int readingID = 0;
 
int counter = 0;
String LoRaMessage = "";
 
//Initialize LoRa module
  void startLoRA()
  {
   LoRa.setPins(CS, RST, DIO); //setup LoRa transceiver module
 
  while (!LoRa.begin(BAND) && counter < 10) {
    Serial.print(".");
    counter++;
    delay(500);
  }
  if (counter == 10) 
  {
    // Increment readingID on every new reading
    readingID++;
    Serial.println("Starting LoRa failed!"); 
  }
  Serial.println("LoRa Initialization OK!");
  delay(2000);
}

void sendReadings() {
  LoRaMessage = String(readingID) + "/" + String(dustSensor.getDustDensity()) + "&" + String(dustSensor.getRunningAverage()) ;
  //Send LoRa packet to receiver
  LoRa.beginPacket();
  LoRa.print(LoRaMessage);
  LoRa.endPacket();
  
  Serial.print("Sending packet: ");
  Serial.println(readingID);
  readingID++;
  Serial.println(LoRaMessage);
}

void setup() {
  Serial.begin(115200);
  //dustSensor.setBaseline(0.4); // set no dust voltage according to your own experiments
  //dustSensor.setCalibrationFactor(1.1); // calibrate against precision instrument
  dustSensor.begin();
  u8g2.begin();
  startLoRA();
}

void loop() {
  
  sendReadings();
  delay(500);

  //Se imprime en el monitor serial
  Serial.print("Dust density: ");
  Serial.print(dustSensor.getDustDensity());
  Serial.print(" ug/m3; Running average: ");

  Serial.print(dustSensor.getRunningAverage());
  Serial.println(" ug/m3");
  delay(1000);

  //Se imprime en la pantalla Oled
  u8g2.clearBuffer();                          //Limpiar la memoria interna
  u8g2.setFont(u8g2_font_pxplusibmvga9_tr);    //Elija una fuente adecuada en https://github.com/olikraus/u8g2/wiki/fntlistall
  u8g2.drawStr(0,15,"Dust Density ");          //Escribe algo en la memoria interna
  u8g2.setCursor(0, 31);
  u8g2.print(dustSensor.getDustDensity()); 
  u8g2.sendBuffer();                           //Transferir la memoria interna a la pantalla
  delay(1000);

  }

The error is as follows:

Maestro_LoRa:33:18: error: expected initializer before '.' token
String dustSensor.getDustDensity();
^
Maestro_LoRa:34:18: error: expected initializer before '.' token
String dustSensor.getRunningAverage();
^
C:\Users\Darel\Desktop\Importante\Red LoRa 2021\Maestro_LoRa\Maestro_LoRa.ino: In function 'String processor(const String&)':
Maestro_LoRa:43:12: error: 'dustSensor' was not declared in this scope
return dustSensor.getDustDensity();
^~~~~~~~~~
C:\Users\Darel\Desktop\Importante\Red LoRa 2021\Maestro_LoRa\Maestro_LoRa.ino:43:12: note: suggested alternative: 'strerror'
return dustSensor.getDustDensity();
^~~~~~~~~~
strerror
Maestro_LoRa:47:12: error: 'dustSensor' was not declared in this scope
return dustSensor.getRunningAverage();
^~~~~~~~~~
C:\Users\Darel\Desktop\Importante\Red LoRa 2021\Maestro_LoRa\Maestro_LoRa.ino:47:12: note: suggested alternative: 'strerror'
return dustSensor.getRunningAverage();
^~~~~~~~~~
strerror
C:\Users\Darel\Desktop\Importante\Red LoRa 2021\Maestro_LoRa\Maestro_LoRa.ino: In function 'void loop()':
Maestro_LoRa:107:5: error: 'dustSensor' was not declared in this scope
dustSensor.getDustDensity() = LoRaData.substring(pos1 +1, pos2); // Obtener densidad de polvo
^~~~~~~~~~
C:\Users\Darel\Desktop\Importante\Red LoRa 2021\Maestro_LoRa\Maestro_LoRa.ino:107:5: note: suggested alternative: 'strerror'
dustSensor.getDustDensity() = LoRaData.substring(pos1 +1, pos2); // Obtener densidad de polvo
^~~~~~~~~~
strerror
Maestro_LoRa:123:25: error: 'dustSensor' was not declared in this scope
postStr += String(dustSensor.getDustDensity());
^~~~~~~~~~
C:\Users\Darel\Desktop\Importante\Red LoRa 2021\Maestro_LoRa\Maestro_LoRa.ino:123:25: note: suggested alternative: 'strerror'
postStr += String(dustSensor.getDustDensity());
^~~~~~~~~~
strerror
exit status 1
expected initializer before '.' token

2

where is "dustSensor" initialized in "master" code?
where is function block names "dustSensor.getDustDensity()"?
you using a function name as a string name.
rename such weird string to simple "DustDensity"

3

As @kolaha say rename these to, for example

String dustDensityStr;  // these are Strings not numbers
String dunningAverageStr;
4

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