Can't insert values in sqlite database because of the model file in Flutter

Question

I am trying to parse this API response below and saving the response in a sqlite database. But getting this error message in the saving process.. And I think it happens because I cant properly create this model file. Can't figure it out how to implement 2 class within the "Map<String, Object?> toJson()" section.

Error:

 Invalid argument [{id: 1, name: İstanbul Ayasofya Müzesi, session_time: 12, distId: AYS, photo: https://api.thevoiceofmuseums.com/storage/contents/museums/1.jpeg, address: null, lat: null, long: null, sectionId: AYS01, email: null, updated_at: 2019-07-20T13:42:53.000, created_at: 2019-06-20T02:27:21.000}, {id: 2, name: İstanbul Topkapı Sarayı Müzesi, session_time: 12, distId: TPK01, photo: https://api.thevoiceofmuseums.com/storage/contents/museums/2.jpeg, address: null, lat: null, long: null, sectionId: TPK01, email: null, updated_at: 2019-07-20T13:44:12.000, created_at: 2019-06-21T14:11:43.000}, {id: 3, name: İstanbul Topkapı Sarayı - Harem Dairesi, session_time: 12, distId: TPK02, photo: https://api.thevoiceofmuseums.com/storage/contents/museums/3.jpeg, address: null, lat: null, long: null, sectionId: TPK02, email: null, updated_at: 2019-07-20T13:44:22.000, created_at: 2019-06-21T14:12:48.000}, {id: 4, name: İstanbul Topkapı Sarayı Müzesi ve Harem Dairesi, session_time: 12, di
E/flutter ( 7093): [ERROR:flutter/lib/ui/ui_dart_state.cc(186)] Unhandled Exception: DatabaseException(java.util.HashMap cannot be cast to java.lang.Integer) sql 'INSERT INTO museums_list.db (data) VALUES (?)' args

Table View screenshot:

Here is my endpoint response:

{
    "data": [
        {
            "id": 1,
            "name": "İstanbul Ayasofya Müzesi",
            "session_time": 12,
            "distId": "AYS",
            "photo": "https://api.thevoiceofmuseums.com/storage/contents/museums/1.jpeg",
            "address": "null",
            "lat": "null",
            "long": "null",
            "sectionId": "AYS01",
            "email": "null",
            "updated_at": "2019-07-20 13:42:53",
            "created_at": "2019-06-20 02:27:21"
        },
        {
            "id": 2,
            "name": "İstanbul Topkapı Sarayı Müzesi",
            "session_time": 12,
            "distId": "TPK01",
            "photo": "https://api.thevoiceofmuseums.com/storage/contents/museums/2.jpeg",
            "address": "null",
            "lat": "null",
            "long": "null",
            "sectionId": "TPK01",
            "email": "null",
            "updated_at": "2019-07-20 13:44:12",
            "created_at": "2019-06-21 14:11:43"
        },
        {
            "id": 3,
            "name": "İstanbul Topkapı Sarayı - Harem Dairesi",
            "session_time": 12,
            "distId": "TPK02",
            "photo": "https://api.thevoiceofmuseums.com/storage/contents/museums/3.jpeg",
            "address": "null",
            "lat": "null",
            "long": "null",
            "sectionId": "TPK02",
            "email": "null",
            "updated_at": "2019-07-20 13:44:22",
            "created_at": "2019-06-21 14:12:48"
        }
    ]
}

model file:

final String tableMuseums = 'MuseumsListTable';

// column names for database
class MuseumsFields {
  static const String MUSEUM_ID = 'id';
  static const String MUSEUM_NAME = 'name';
  static const String SESSION_TIME = 'session_time';
  static const String MUSEUM_DIST_ID = 'distId';
  static const String MUSEUM_PHOTO = 'photo';
  static const String MUSEUM_ADDRESS = 'address';
  static const String LAT = 'lat';
  static const String LONG = 'long';
  static const String MUSEUM_SECTION_ID = 'sectionId';
  static const String EMAIL = 'email';
  static const String UPDATED_AT = 'updated_at';
  static const String CREATED_AT = 'created_at';
}

class MuseumsList {
  List<Data>? data;

  MuseumsList({this.data});

  MuseumsList.fromJson(Map<String, dynamic> json) {
    if (json['data'] != null) {
      data = <Data>[];
      json['data'].forEach((v) {
        data!.add(new Data.fromJson(v));
      });
    }
  }

  Map<String, dynamic> toJson() {
    print("TOJSON");
    final Map<String, dynamic> data = new Map<String, dynamic>();
    if (this.data != null) {
      data['data'] = this.data!.map((v) => v.toJson()).toList();
    }
    return data;
  }
}

class Data {
  int? id;
  String? name;
  int? sessionTime;
  String? distId;
  String? photo;
  String? address;
  String? lat;
  String? long;
  String? sectionId;
  String? email;
  DateTime? updatedAt;
  DateTime? createdAt;

  Data({
    this.id,
    this.name,
    this.sessionTime,
    this.distId,
    this.photo,
    this.address,
    this.lat,
    this.long,
    this.sectionId,
    this.email,
    this.updatedAt,
    this.createdAt,
  });


  Data.fromJson(Map<String, dynamic> json) {
    id = json['id'];
    name = json['name'];
    sessionTime = json['session_time'];
    distId = json['distId'];
    photo = json['photo'];
    address = json['address'];
    lat = json['lat'];
    long = json['long'];
    sectionId = json['sectionId'];
    email = json['email'];
    updatedAt = DateTime.parse(json["updated_at"]);
    createdAt = DateTime.parse(json["created_at"]);
  }

  Map<String, Object?> toJson() => {
        MuseumsFields.MUSEUM_ID: id,
        MuseumsFields.MUSEUM_NAME: name,
        MuseumsFields.SESSION_TIME: sessionTime,
        MuseumsFields.MUSEUM_DIST_ID: distId,
        MuseumsFields.MUSEUM_PHOTO: photo,
        MuseumsFields.MUSEUM_ADDRESS: address,
        MuseumsFields.LAT: lat,
        MuseumsFields.LONG: long,
        MuseumsFields.MUSEUM_SECTION_ID: sectionId,
        MuseumsFields.EMAIL: email,
        MuseumsFields.UPDATED_AT: updatedAt!.toIso8601String(),
        MuseumsFields.CREATED_AT: createdAt!.toIso8601String(),
      };
}

database provider file:

import 'dart:io';
import 'package:path/path.dart';
import 'package:the_vom/models/museums_list_model.dart';

import 'package:path_provider/path_provider.dart';
import 'package:sqflite/sqflite.dart';

class DBProvider {
  static final DBProvider instance = DBProvider._init();
  static Database? _database;
  DBProvider._init();

  Future<Database?> get database async {
    if (_database != null) return _database!;

    _database = await _initDB('museums.db');
    return _database;
  }

  Future<Database> _initDB(String filePath) async {
    // final dbPath = await getDatabasesPath();
    Directory documentsDirectory = await getApplicationDocumentsDirectory();
    String path = join(documentsDirectory.path, filePath);
    print('database location: $path');

    return await openDatabase(path, version: 1, onCreate: _createDB);
  }

  Future _createDB(Database db, int version) async {
    final idType = 'INTEGER PRIMARY KEY';
    final textType = 'TEXT';
    final intType = 'INTEGER';

    await db.execute('''
    CREATE TABLE $tableMuseums (
    ${MuseumsFields.MUSEUM_ID} $idType,
    ${MuseumsFields.MUSEUM_NAME} $textType,
    ${MuseumsFields.SESSION_TIME} $intType,
    ${MuseumsFields.MUSEUM_DIST_ID} $textType,
    ${MuseumsFields.MUSEUM_PHOTO} $textType,
    ${MuseumsFields.MUSEUM_ADDRESS} $textType,
    ${MuseumsFields.LAT} $textType,
    ${MuseumsFields.LONG} $textType,
    ${MuseumsFields.MUSEUM_SECTION_ID} $textType,
    ${MuseumsFields.EMAIL} $textType,
    ${MuseumsFields.UPDATED_AT} $textType,
    ${MuseumsFields.CREATED_AT} $textType
    )
     ''');

    print("database table is created.");
  }

  Future<MuseumsList> create(MuseumsList museum) async {
    print("inside of create function in db_provider.dart");
    final db = await instance.database;

    final json = museum.toJson();
    print("+++++++++++");
    print(json.values);
    print("+++++++++++");
    // // COLUMN NAMES
    // final columns =
    //     '${MuseumsFields.MUSEUM_ID}, ${MuseumsFields.MUSEUM_NAME},  ${MuseumsFields.SESSION_TIME},  ${MuseumsFields.MUSEUM_DIST_ID},  ${MuseumsFields.MUSEUM_PHOTO},  ${MuseumsFields.MUSEUM_ADDRESS},  ${MuseumsFields.LAT},  ${MuseumsFields.LONG},  ${MuseumsFields.MUSEUM_SECTION_ID},  ${MuseumsFields.EMAIL},  ${MuseumsFields.UPDATED_AT},  ${MuseumsFields.CREATED_AT}';
    // // ROWS
    // final values =
    //     '${json[MuseumsFields.MUSEUM_ID]}, ${json[MuseumsFields.MUSEUM_NAME]}, ${json[MuseumsFields.SESSION_TIME]}, ${json[MuseumsFields.MUSEUM_DIST_ID]}, ${json[MuseumsFields.MUSEUM_PHOTO]}, ${json[MuseumsFields.MUSEUM_ADDRESS]}, ${json[MuseumsFields.LAT]}, ${json[MuseumsFields.LONG]}, ${json[MuseumsFields.MUSEUM_SECTION_ID]}, ${json[MuseumsFields.EMAIL]}, ${json[MuseumsFields.UPDATED_AT]}, ${json[MuseumsFields.CREATED_AT]}';
    //
    // final y = await db!
    //     .rawInsert('INSERT INTO $tableMuseums ($columns) VALUES ($values)');

    final x =
        await db!.insert(tableMuseums, museum.toJson()); //convert to a map.

    print("museums are saved in the database.");

    return museum;
  }

  Future close() async {
    final db = await instance.database;

    db!.close();
  }
}

service file: I pass my decoded response.body to db provider here as you can see below.

class MuseumsService {
  Future getMuseums() async {
    print("Future getMuseums");
    try {
      // headers of the post request
      final _headers = {
        //todo bearer token, remove the hardcoded one.
        'Authorization': _hardCodedBearerToken,
        'Content-Type': 'application/x-www-form-urlencoded',
      };

      // body of the post request
      // final _body = '';

      // sending post request
      http.Response response = await http.post(
        loginAPIURL,
        headers: _headers,
        // body: _body,
      );
      print("getMuseums Request Sent!");

      //get response from endpoint
      if (response.statusCode == 200) {
        print('$loginAPIURL Endpoint Response: response.body');
        print(response.body);

        MuseumsList museums =
            await MuseumsList.fromJson(jsonDecode(response.body));

        // print(museums.data![0].name);

        DBProvider.instance.create(museums); //-> **** 
      }
    } catch (e) {
      print(e);
      return throw Exception("MUSEUMSLIST ALINAMADI");
    }
  }
}

Luis A. Chaglla · Accepted Answer · 2021-04-29 17:35:04Z

1

You are trying to insert the result of MuseumsList.toJson instead of Data.toJson

Try with something like this:

Future<MuseumsList> create(MuseumsList museums) async {
  print("inside of create function in db_provider.dart");
  final db = await instance.database;

  // {'data': [...]}
  final jsons = museums.toJson();
  if (jsons['data'] != null) {
    batch = db!.batch();

    jsons['data'].forEach((museum) {
      batch.insert(tableMuseums, museum);
    });

    await batch.commit();
  }

  print("museums are saved in the database.");

  return museums;
}

answered Apr 29, 2021 at 17:35

Luis A. Chaglla

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