Convert struct array to json array and vise vera

[johnwasser]

The ArduinoJson.org/v6/Assistant will do most of the code writing for you. Here is a way to make your original "array of structures work:

{
  "modules": [
    {
      "modulesrno": 0,
      "moduleID": "123456",
      "moduletype": "M41",
      "moduleNRFID": "1"
    },
    {
      "modulesrno": 1,
      "moduleID": "123457",
      "moduletype": "M42",
      "moduleNRFID": "2"
    },
    {
      "modulesrno": 2,
      "moduleID": "123457",
      "moduletype": "M42",
      "moduleNRFID": "3"
    },
    {
      "modulesrno": 3,
      "moduleID": "123457",
      "moduletype": "M42",
      "moduleNRFID": "2"
    },
    {
      "modulesrno": 4,
      "moduleID": "123457",
      "moduletype": "M42",
      "moduleNRFID": "2"
    },
    {
      "modulesrno": 5,
      "moduleID": "123457",
      "moduletype": "M42",
      "moduleNRFID": "2"
    },
    {
      "modulesrno": 6,
      "moduleID": "123457",
      "moduletype": "M42",
      "moduleNRFID": "2"
    },
    {
      "modulesrno": 7,
      "moduleID": "123457",
      "moduletype": "M42",
      "moduleNRFID": "2"
    },
    {
      "modulesrno": 8,
      "moduleID": "123457",
      "moduletype": "M42",
      "moduleNRFID": "2"
    },
    {
      "modulesrno": 1,
      "moduleID": "123457",
      "moduletype": "M42",
      "moduleNRFID": "2"
    },
    {
      "modulesrno": 1,
      "moduleID": "123457",
      "moduletype": "M42",
      "moduleNRFID": "2"
    },
    {
      "modulesrno": 1,
      "moduleID": "123457",
      "moduletype": "M42",
      "moduleNRFID": "2"
    },
    {
      "modulesrno": 1,
      "moduleID": "123457",
      "moduletype": "M42",
      "moduleNRFID": "2"
    },
    {
      "modulesrno": 1,
      "moduleID": "123457",
      "moduletype": "M42",
      "moduleNRFID": "2"
    },
    {
      "modulesrno": 1,
      "moduleID": "123457",
      "moduletype": "M42",
      "moduleNRFID": "2"
    },
    {
      "modulesrno": 1,
      "moduleID": "123457",
      "moduletype": "M42",
      "moduleNRFID": "2"
    },
    {
      "modulesrno": 1,
      "moduleID": "123457",
      "moduletype": "M42",
      "moduleNRFID": "2"
    },
    {
      "modulesrno": 1,
      "moduleID": "123457",
      "moduletype": "M42",
      "moduleNRFID": "2"
    },
    {
      "modulesrno": 1,
      "moduleID": "123457",
      "moduletype": "M42",
      "moduleNRFID": "2"
    },
    {
      "modulesrno": 1,
      "moduleID": "123457",
      "moduletype": "M42",
      "moduleNRFID": "2"
    },
    {
      "modulesrno": 1,
      "moduleID": "123457",
      "moduletype": "M42",
      "moduleNRFID": "2"
    },
    {
      "modulesrno": 1,
      "moduleID": "123457",
      "moduletype": "M42",
      "moduleNRFID": "2"
    },
    {
      "modulesrno": 1,
      "moduleID": "123457",
      "moduletype": "M42",
      "moduleNRFID": "2"
    },
    {
      "modulesrno": 1,
      "moduleID": "123457",
      "moduletype": "M42",
      "moduleNRFID": "2"
    },
    {
      "modulesrno": 1,
      "moduleID": "123457",
      "moduletype": "M42",
      "moduleNRFID": "2"
    },
    {
      "modulesrno": 1,
      "moduleID": "123457",
      "moduletype": "M42",
      "moduleNRFID": "2"
    },
    {
      "modulesrno": 1,
      "moduleID": "123457",
      "moduletype": "M42",
      "moduleNRFID": "2"
    },
    {
      "modulesrno": 1,
      "moduleID": "123457",
      "moduletype": "M42",
      "moduleNRFID": "2"
    },
    {
      "modulesrno": 1,
      "moduleID": "123457",
      "moduletype": "M42",
      "moduleNRFID": "2"
    },
    {
      "modulesrno": 1,
      "moduleID": "123457",
      "moduletype": "M42",
      "moduleNRFID": "2"
    }
  ]
}

#include <ArduinoJson.h>
#include <LittleFS.h>

struct ConfigModule
{
  signed int modulesrno;
  // String      moduletimestamp;
  String      moduleID;
  // String      moduleplacename;
  // String      moduleplaceID;
  // String      moduleroomname;
  // String      moduleroomID;
  String      moduletype;
  String      moduleNRFID;

} configmod[30];

StaticJsonDocument<3072> doc;

void setup()
{
  Serial.begin(115200);
  delay(200);
  
  // always use this to "mount" the filesystem
  bool result = LittleFS.begin();
  Serial.println("LittleFS opened: " + result);

  File file = LittleFS.open("/configmod.json", "r");
  if (!file) return;

  DeserializationError error = deserializeJson(doc, file);

  if (error)
  {
    Serial.print(F("deserializeJson() failed: "));
    Serial.println(error.f_str());
    return;
  }

  for (JsonObject module : doc["modules"].as<JsonArray>())
  {
    int srno = module["modulesrno"];
    
    configmod[srno].modulesrno = srno;
    configmod[srno].moduleID = module["moduleID"].as<String>();
    configmod[srno].moduletype = module["moduletype"].as<String>();
    configmod[srno].moduleNRFID = module["moduleNRFID"].as<String>();
  }
}

void loop() {}