Read Firebase RTDB Data Only on Updates (ESP8266 or ESP32)

[KKBUGHUNTER]

I'm working with the following code that reads data from a Firebase

#include <Arduino.h>
#if defined(ESP32) || defined(ARDUINO_RASPBERRY_PI_PICO_W)
#include <WiFi.h>
#elif defined(ESP8266)
#include <ESP8266WiFi.h>
#elif __has_include(<WiFiNINA.h>)
#include <WiFiNINA.h>
#elif __has_include(<WiFi101.h>)
#include <WiFi101.h>
#elif __has_include(<WiFiS3.h>)
#include <WiFiS3.h>
#endif

#include <Firebase_ESP_Client.h>
#include <addons/TokenHelper.h>
#include <addons/RTDBHelper.h>

#define WIFI_SSID ""
#define WIFI_PASSWORD ""
#define API_KEY ""
#define DATABASE_URL ""
#define USER_EMAIL ""
#define USER_PASSWORD ""

FirebaseData fbdo;
FirebaseAuth auth;
FirebaseConfig config;

unsigned long sendDataPrevMillis = 0;
unsigned long count = 0;



void setup()
{

  Serial.begin(115200);

  WiFi.begin(WIFI_SSID, WIFI_PASSWORD);


  Serial.print("Connecting to Wi-Fi");
  unsigned long ms = millis();
  while (WiFi.status() != WL_CONNECTED)
  {
    Serial.print(".");
    delay(300);

  }
  Serial.println();
  Serial.print("Connected with IP: ");
  Serial.println(WiFi.localIP());
  Serial.println();

  Serial.printf("Firebase Client v%s\n\n", FIREBASE_CLIENT_VERSION);

  config.api_key = API_KEY;
  config.database_url = DATABASE_URL;
  auth.user.email = USER_EMAIL;
  auth.user.password = USER_PASSWORD;

  
  config.token_status_callback = tokenStatusCallback;
  Firebase.reconnectNetwork(true);
  fbdo.setBSSLBufferSize(4096, 1024);
  fbdo.setResponseSize(2048);
  Firebase.begin(&config, &auth);


  Firebase.setDoubleDigits(5);
  config.timeout.serverResponse = 10 * 1000;
}

void loop()
{

  if (Firebase.ready())
  {

    Serial.printf("Get string... %s\n", Firebase.RTDB.getString(&fbdo, F("/test/string")) ? fbdo.to<const char *>() : fbdo.errorReason().c_str());

    Serial.println();
  }
}

Currently, the code reads data continuously from the path "/s1" in the database. I'd like to modify it to read data only when there's an update in the database at that path.

I've looked into the Firebase library documentation for stream functions, but I'm not sure how to integrate them effectively.

Could anyone provide guidance on how to achieve this behavior using the stream function or suggest alternative approaches, like event listeners?

[mobizt]

https://github.com/mobizt/Firebase-ESP-Client/tree/main/examples/RTDB/DataChangesListener