Objectbox 不以一对多关系存储可为 null 的值

Question

我有这样的一对多关系。

@Entity()
class Product {
  @Id()
  int id;
  String name;
  String category;
  int categoryId;
  WeightType weightType;
  double? price;
  double weight;
  bool isRefunded;

  Product({
    this.id = 0,
    required this.name,
    required this.category,
    required this.categoryId,
    this.weightType = WeightType.kg,
    this.price,
    this.weight = 0,
    this.isRefunded = false,
  });

  Product copy() => Product(
        name: name,
        category: category,
        id: id,
        price: price,
        weight: weight,
        weightType: weightType,
        categoryId: categoryId,
        isRefunded: isRefunded,
      );

  String getInfo(int index) {
    switch (index) {
      case 1:
        return name;
      case 2:
        return price.toString();
      case 3:
        return weight.toString() + ' ' + weightType.getName();
      case 4:
        if (weightType == WeightType.kg) {
          return (price! * weight).toString();
        } else {
          return (price! * (weight / 1000)).toString();
        }
      default:
        return '';
    }
  }
}

@Entity()
class Pdf {
  @Id()
  int id;
  Uint8List pdfData;
  final String customerName;
  @Property(type: PropertyType.date)
  final DateTime purchaseDate;
  ToMany<Product> products; //<----------- the relation
  double totalAmount;
  PaymentStatus paymentStatus;
  @Property(type: PropertyType.date)
  DateTime? updateDate;

  Pdf({
    this.id = 0,
    required this.pdfData,
    required this.purchaseDate,
    required this.customerName,
    required this.totalAmount,
    required this.products,
    this.paymentStatus = PaymentStatus.unPaid,
    this.updateDate,
  });

  int get status => paymentStatus.index;

  set status(int value) {
    paymentStatus = PaymentStatus.values[value];
  }
}

现在我如何将数据添加到db，

void addToDb(Bill bill){
final billPdf = Pdf(
      pdfData: pdf,
      purchaseDate: DateTime.now(),
      customerName: bill.customerName,
      totalAmount: bill.totalAmount,
      paymentStatus: bill.paymentStatus,
      products: obj.ToMany(items: bill.products) //<------- this is the product list
    );
    DBService.pdfBox.put(billPdf,mode: obj.PutMode.insert);
}

现在在执行Dbservice.pdfbox.put()

执行后Dbservice.pdfbox.put()

您可以看到 price 和 weight 不为 null，而且 RelInfo 也不是null（它有一个参数为 null）

现在，当我从数据库获取数据时，我得到的所有数据与我输入的数据相同，除了可为空的变量或包含默认值的变量。它们是价格、重量和'weightType`。

您可以在这里看到，

最后，这就是我创建 objectbox store 的方法，

class DBService {
  static late final Store store;

  static late final Box<Product> productBox;

  static late final Box<Category> categoryBox;

  static late final Box<Pdf> pdfBox;

  DBService._();

  static Future<void> create() async {
    store = await openStore();
    productBox = store.box();
    categoryBox = store.box();
    pdfBox = store.box();
  }
}

在 main() 中调用 create() code>

如果我把 final pdf = ToOne() 在产品模型中，然后我之前问的问题又出现了。

这是哪个-> 如何在objectbox的框中多次添加相同的对象？< /a>

现在你们能告诉我为什么只有可为空的/具有默认值的才没有存储在 objectbox 数据库中吗？