getItem method
Implementation
Future<Map<String, dynamic>?> getItem({
required String tableName,
String? fieldName = 'id',
required String fieldValue,
}) async {
final db = await database;
final res = await db.query(
tableName,
where: '$fieldName = ?',
whereArgs: [fieldValue],
);
return res.isNotEmpty ? _deserializeItem(res.first) : null;
}