Thailand's covid stat daily model class with support non-nullable in Flutter 2.0

covid_stat_model.dart

// To parse this JSON data, do
//
//     final covidStatModel = covidStatModelFromJson(jsonString);

import 'dart:convert';

List<CovidStatModel> covidStatModelFromJson(String str) =>
    List<CovidStatModel>.from(
        json.decode(str).map((x) => CovidStatModel.fromJson(x)));

String covidStatModelToJson(List<CovidStatModel> data) =>
    json.encode(List<dynamic>.from(data.map((x) => x.toJson())));

class CovidStatModel {
  CovidStatModel({
    required this.txnDate,
    required this.newCase,
    required this.totalCase,
    required this.newCaseExcludeabroad,
    required this.totalCaseExcludeabroad,
    required this.newDeath,
    required this.totalDeath,
    required this.newRecovered,
    required this.totalRecovered,
    required this.updateDate,
  });

  DateTime? txnDate;
  int? newCase;
  int? totalCase;
  int? newCaseExcludeabroad;
  int? totalCaseExcludeabroad;
  int? newDeath;
  int? totalDeath;
  int? newRecovered;
  int? totalRecovered;
  DateTime? updateDate;

  factory CovidStatModel.fromJson(Map<String, dynamic> json) => CovidStatModel(
        txnDate:
            json["txn_date"] == null ? null : DateTime.parse(json["txn_date"]),
        newCase: json["new_case"] == null ? null : json["new_case"],
        totalCase: json["total_case"] == null ? null : json["total_case"],
        newCaseExcludeabroad: json["new_case_excludeabroad"] == null
            ? null
            : json["new_case_excludeabroad"],
        totalCaseExcludeabroad: json["total_case_excludeabroad"] == null
            ? null
            : json["total_case_excludeabroad"],
        newDeath: json["new_death"] == null ? null : json["new_death"],
        totalDeath: json["total_death"] == null ? null : json["total_death"],
        newRecovered:
            json["new_recovered"] == null ? null : json["new_recovered"],
        totalRecovered:
            json["total_recovered"] == null ? null : json["total_recovered"],
        updateDate: json["update_date"] == null
            ? null
            : DateTime.parse(json["update_date"]),
      );

  Map<String, dynamic> toJson() => {
        "txn_date": txnDate == null
            ? null
            : "${txnDate?.year.toString().padLeft(4, '0')}-${txnDate?.month.toString().padLeft(2, '0')}-${txnDate?.day.toString().padLeft(2, '0')}",
        "new_case": newCase == null ? null : newCase,
        "total_case": totalCase == null ? null : totalCase,
        "new_case_excludeabroad":
            newCaseExcludeabroad == null ? null : newCaseExcludeabroad,
        "total_case_excludeabroad":
            totalCaseExcludeabroad == null ? null : totalCaseExcludeabroad,
        "new_death": newDeath == null ? null : newDeath,
        "total_death": totalDeath == null ? null : totalDeath,
        "new_recovered": newRecovered == null ? null : newRecovered,
        "total_recovered": totalRecovered == null ? null : totalRecovered,
        "update_date":
            updateDate == null ? null : updateDate?.toIso8601String(),
      };
}

Convert http response's data to Dart object with model class generated from Quicktype.io

if (snapshot.connectionState == ConnectionState.done) {
            var response = snapshot.data;
            var json = response?.body as String;
            var model = covidStatModelFromJson(json);
            return Text('ok');
          }

URL for this JSON:

https://covid19.ddc.moph.go.th/api/Cases/today-cases-all