(ObjectBox | Dart) 如何将 json 传递给实体类？

编程问答 2022-09-05

问题描述

JSON 是：

{
    "name": "Leanne Graham","username": "Bret","email": "Sincere@april.biz","address": {
      "street": "Kulas Light","suite": "Apt. 556","city": "Gwenborough","zipcode": "92998-3874","geo": {
        "lat": "-37.3159","lng": "81.1496"
      }
    },"phone": "1-770-736-8031 x56442","website": "hildegard.org","company": {
      "name": "Romaguera-Crona","catchPhrase": "multi-layered client-server neural-net","bs": "harness real-time e-markets"
    }
  }

我为User、Address、Geo、Company 以及这些的扩展创建了四个实体类实体 usermodel、AddressModel、GeoModel、CompanyModel，其中每个模型都有 @JsonSerializable 批注以将 JSON 转换为楷模。 现在让我们以地址为例。问题在于当我必须将 AddressModel 传递给 User 实体类时 - 首先我在 User 构造函数中没有地址字段，User 类中的第二个地址现在是 final address = ToOne()，这不是地址类型。所以 JsonSerializable 要求我提供 toJson 和 fromJson 到 ToOne 类。

有什么好的例子吗，我如何将 json_serializable 包和 objectBox 与链接对象一起使用，例如这个 json，因为我正在努力解决它？

以下是 JSON 可序列化模型：

@JsonSerializable(explicitToJson: true)
class usermodel extends User {
  final String name;
  final String username;
  final String email;
  final AddressModel address;
  final String phone;
  final String website;
  final CompanyModel company;

  usermodel({
    required this.name,required this.username,required this.email,required this.address,required this.phone,required this.website,required this.company,}) : super(
          name: name,username: username,email: email,address: address,phone: phone,website: website,company: company,);

  factory usermodel.fromJson(Map<String,dynamic> json) =>
      _$usermodelFromJson(json);
  Map<String,dynamic> toJson() => _$usermodelToJson(this);
}

// ADDRESS
@JsonSerializable(explicitToJson: true)
class AddressModel extends Address {
  final String street;
  final String suite;
  final String city;
  final String zipcode;
  final GeoModel geo;
  AddressModel({
    required this.street,required this.suite,required this.city,required this.zipcode,required this.geo,}) : super(
          street: street,suite: suite,city: city,zipcode: zipcode,geo: geo,);

  factory AddressModel.fromJson(Map<String,dynamic> json) =>
      _$AddressModelFromJson(json);
  Map<String,dynamic> toJson() => _$AddressModelToJson(this);
}

// COMPANY
@JsonSerializable()
class CompanyModel extends Company {
  final String name;
  final String catchPhrase;
  final String bs;
  CompanyModel({
    required this.name,required this.catchPhrase,required this.bs,}) : super(name: name,catchPhrase: catchPhrase,bs: bs);

  factory CompanyModel.fromJson(Map<String,dynamic> json) =>
      _$CompanyModelFromJson(json);
  Map<String,dynamic> toJson() => _$CompanyModelToJson(this);
}

// GEO
@JsonSerializable()
class GeoModel extends Geo {
  final String lat;
  final String lng;
  GeoModel({
    required this.lat,required this.lng,}) : super(lat: lat,lng: lng);

  factory GeoModel.fromJson(Map<String,dynamic> json) =>
      _$GeoModelFromJson(json);
  Map<String,dynamic> toJson() => _$GeoModelToJson(this);
}

以下是实体类：

class User {
  final String name;
  final String username;
  final String email;
  final Address address;
  final String phone;
  final String website;
  final Company company;

  User({
    required this.name,});
}

// ADDRESS
class Address {
  final String street;
  final String suite;
  final String city;
  final String zipcode;
  final Geo geo;
  Address({
    required this.street,});
}

// COMPANY
class Company {
  final String name;
  final String catchPhrase;
  final String bs;
  Company({
    required this.name,});
}

// GEO
class Geo {
  final String lat;
  final String lng;
  Geo({
    required this.lat,});
}

虽然我可以在我的应用程序中使用实体，但我不知道如何使用 ToOne，因此我可以将 User 对象保存在 ObjectBox 数据库中，并带有指向 Address、Geo 和 Company 对象的链接。

解决方法

这可能是我发现如何设法将它们组合在一起的方式，但这不是理想的方式，因为在构造函数中清除参数对于 JSON 序列化的实体类结构来说确实很奇怪。

我想要一些更清晰的示例，如何使用 ObjectBox 将 JSON 解析为实体类。到目前为止我找不到任何，只是抽象的解释。

@JsonSerializable(explicitToJson: true)
class UserModel extends User {
  final String name;
  final String username;
  final String email;
  final String phone;
  final String website;

  @JsonKey(name: "address")
  final AddressModel ? addressModel;
  @JsonKey(name: "company")
  final CompanyModel ? companyModel;

  UserModel({
    required this.name,required this.username,required this.email,required this.address,required this.phone,required this.website,required this.company,}) : super(
          name: name,username: username,email: email,phone: phone,website: website,){
      this.address.target = addressModel;
      this.company.target = companyModel;
    }

  factory UserModel.fromJson(Map<String,dynamic> json) =>
      _$UserModelFromJson(json);
  Map<String,dynamic> toJson() => _$UserModelToJson(this);
}

@Entity()
class User {
  @JsonKey(ignore: true)
  int id = 0;

  final String name;
  final String username;
  final String email;
  final String phone;
  final String website;

  @JsonKey(ignore: true)
  final address= ToOne<Address>();

  @JsonKey(ignore: true)
  final company= ToOne<Company>();

  User({
    required this.name,});
}
dartjsonobjectbox