getById method
Retrieves the item with the given id
from the local database.
Returns null if the item is not found.
Implementation
@override
Future<T?> getById(String id) async {
final maps = await (database).query(
tableName,
where: 'id = ?',
whereArgs: [id], // Use placeholders for SQL injection prevention
);
return maps.isNotEmpty ? fromJson(maps.first) : null;
}