How to storage sensors value in JSON string - c

Question

i'm doing with JSON string, i want to storage my sensor data to JSON string then i will send it to Node red or firebase (which i heard is it need JSON format, not sure about that). My actually project is receive lots of sensors value like
["ID": 01, "temp": value_temp_1, "humid": value_humid_1] , ["ID": 02, "temp": value_temp_2, "humid": value_humid_2],...
#include <DHT.h>
#include <DHT_U.h>
#include <ArduinoJson.h>
#define DHTPIN 2
#define DHTTYPE DHT11
DHT dht(DHTPIN, DHTTYPE);
int humidity, temperature;
void setup() {
// put your setup code here, to run once:
Serial.begin(9600);
Serial.println("Begin");
dht.begin();
}
void loop()
{
delay(2000);
humidity = dht.readHumidity();
temperature = dht.readTemperature();
StaticJsonDocument<50> doc;
JsonObject object = doc.to<JsonObject>();
object["ID"] = "Node01";
object["humidity"] = humidity;
object["temperature"] = temperature;
serializeJson(doc, Serial);
Serial.println("");
}
my question is do i have to use those code in loop()? everytime it will create a Json<50> so it will be full later or it only create 1 time? i have little confuse about that or could anyone give me some advices to optimize my code.
thank you

Answer 1

You don't need to create your object each time. Just define it as a global variable and change its values on your loop. Something like this:
#include <DHT.h>
#include <DHT_U.h>
#include <ArduinoJson.h>
#define DHTPIN 2
#define DHTTYPE DHT11
DHT dht(DHTPIN, DHTTYPE);
int humidity, temperature;
StaticJsonDocument<50> doc;
JsonObject object;
void setup()
{
// put your setup code here, to run once:
Serial.begin(9600);
Serial.println("Begin");
dht.begin();
object = doc.to<JsonObject>();
}
void loop()
{
humidity = dht.readHumidity();
temperature = dht.readTemperature();
object["ID"] = "Node01";
object["humidity"] = humidity;
object["temperature"] = temperature;
serializeJson(doc, Serial);
Serial.println("");
delay(2000);
}