UPDATE我建立了一个小样本,并将所有代码添加到这篇文章中。我必须相信对此有一个答案/解释,并希望有人可以就我所缺少的内容对我进行教育。类型为object的类字段未转换,我不明白为什么。
这是我正在使用的模型类。
import 'package:json_annotation/json_annotation.dart';
part 'parent.g.dart';
@JsonSerializable()
class Parent {
int id;
final String name;
final int age;
List<Child> children;
Job job;
Parent({this.name, this.age, this.children, this.job});
factory Parent.fromJson(Map<String, dynamic> json) => _$ParentFromJson(json);
Map<String, dynamic> toJson() => _$ParentToJson(this);
}
@JsonSerializable()
class Child{
int id;
final String name;
final int age;
Child({this.name, this.age});
factory Child.fromJson(Map<String, dynamic> json) => _$ChildFromJson(json);
Map<String, dynamic> toJson() => _$ChildToJson(this);
}
@JsonSerializable()
class Job{
int id;
String title;
Job({this.title});
factory Job.fromJson(Map<String, dynamic> json) => _$JobFromJson(json);
Map<String, dynamic> toJson() => _$JobToJson(this);
}
这是这些类的.g生成的文件
// GENERATED CODE - DO NOT MODIFY BY HAND
part of 'parent.dart';
// **************************************************************************
// JsonSerializableGenerator
// **************************************************************************
Parent _$ParentFromJson(Map<String, dynamic> json) {
return Parent(
name: json['name'] as String,
age: json['age'] as int,
children: (json['children'] as List)
?.map(
(e) => e == null ? null : Child.fromJson(e as Map<String, dynamic>))
?.toList(),
job: json['job'] == null
? null
: Job.fromJson(json['job'] as Map<String, dynamic>),
)..id = json['id'] as int;
}
Map<String, dynamic> _$ParentToJson(Parent instance) => <String, dynamic>{
'id': instance.id,
'name': instance.name,
'age': instance.age,
'children': instance.children,
'job': instance.job,
};
Child _$ChildFromJson(Map<String, dynamic> json) {
return Child(
name: json['name'] as String,
age: json['age'] as int,
)..id = json['id'] as int;
}
Map<String, dynamic> _$ChildToJson(Child instance) => <String, dynamic>{
'id': instance.id,
'name': instance.name,
'age': instance.age,
};
Job _$JobFromJson(Map<String, dynamic> json) {
return Job(
title: json['title'] as String,
)..id = json['id'] as int;
}
Map<String, dynamic> _$JobToJson(Job instance) => <String, dynamic>{
'id': instance.id,
'title': instance.title,
};
这里是父类的DAO类
import 'package:sembast/sembast.dart';
import 'package:json_serial_test/services/app_database.dart';
import 'package:json_serial_test/models/parent.dart';
class ParentDao {
static const String PARENT_STORE_NAME = 'parents';
// A Store with int keys and Map<String, dynamic> values.
// This Store acts like a persistent map, values of which are Parent objects converted to Map
final _parentStore = intMapStoreFactory.store(PARENT_STORE_NAME);
// Private getter to shorten the amount of code needed to get the
// singleton instance of an opened database.
Future<Database> get _db async => await AppDatabase.instance.database;
Future insert(Parent parent) async {
await _parentStore.add(await _db, parent.toJson());
}
Future update(Parent parent) async {
// For filtering by key (ID), RegEx, greater than, and many other criteria,
// we use a Finder.
final finder = Finder(filter: Filter.byKey(parent.id));
await _parentStore.update(
await _db,
parent.toJson(),
finder: finder,
);
}
Future deleteAll() async {
await _parentStore.delete(await _db);
}
Future delete(Parent parent) async {
final finder = Finder(filter: Filter.byKey(parent.id));
await _parentStore.delete(
await _db,
finder: finder,
);
}
Future<List<Parent>> getAllSortedByName() async {
// Finder object can also sort data.
final finder = Finder(sortOrders: [
SortOrder('name'),
]);
final recordSnapshots = await _parentStore.find(
await _db,
finder: finder,
);
// Making a List<Parent> out of List<RecordSnapshot>
return recordSnapshots.map((snapshot) {
final parent = Parent.fromJson(snapshot.value);
// An ID is a key of a record from the database.
parent.id = snapshot.key;
return parent;
}).toList();
}
}
这是我的考试
// Setup
final k1 = Child(name: 'Billy', age: 10);
final k2 = Child(name: 'Jannet', age: 9);
final job = Job(title: 'Cook');
final List<Child> kids = [k1, k2];
final dad = Parent(name: 'Dave', age: 52, job: job, children: kids);
await pDao.insert(dad);
List<Parent> dadsInDb = await pDao.getAllSortedByName();
print('Dads from DB: ${dadsInDb.toString()}');
在尝试将父项插入到我的sembast数据库中时,这是显示的错误。
E/flutter (12986): [ERROR:flutter/lib/ui/ui_dart_state.cc(157)] Unhandled Exception: Invalid argument(s): value Instance of 'Child' unsupported type Child E/flutter (12986): #0 cloneValue (package:sembast/src/utils.dart:191:3) E/flutter (12986): #1 cloneValue.<anonymous closure> (package:sembast/src/utils.dart:177:33) E/flutter (12986): #2 MappedListIterable.elementAt (dart:_internal/iterable.dart:417:29) E/flutter (12986): #3 ListIterable.toList (dart:_internal/iterable.dart:221:19) E/flutter (12986): #4 cloneValue (package:sembast/src/utils.dart:177:52) E/flutter (12986): #5 cloneValue.<anonymous closure> (package:sembast/src/utils.dart:174:49) E/flutter (12986): #6 MapMixin.map (dart:collection/maps.dart:165:28) E/flutter (12986): #7 cloneValue (package:sembast/src/utils.dart:173:18) E/flutter (12986):
#8 SembastStore.txnPutSync (package:sembast/src/store_impl.dart:133:15) E/flutter (12986): #9 SembastStore.txnAdd (package:sembast/src/store_impl.dart:117:11) E/flutter (12986): <asynchronous suspension> E/flutter (12986): #10 StoreRefMixin.add.<anonymous closure> (package:sembast/src/store_ref_impl.dart:75:12) E/flutter (12986): #11 SembastDatabase.inTransaction.<anonymous closure> (package:sembast/src/database_impl.dart:1238:34) E/flutter (12986):
#12 SembastDatabase.transaction.<anonymous closure>.<anonymous closure> (package:sembast/src/database_impl.dart:1090:59) E/flutter (12986): #13 new Future.sync (dart:async/future.dart:224:31) E/flutter (12986): #14 SembastDatabase.transaction.<anonymous closure> (package:sembast/src/database_impl.dart:1090:26) E/flutter (12986): #15 BasicLock.synchronized (package:synchronized/src/basic_lock.dart:32:26) E/flutter (12986):
#16 SembastDatabase.transaction (package:sembast/src/database_impl.dart:1073:38) E/flutter (12986):
#17 SembastDatabase.inTransaction (package:sembast/src/database_impl.dart:1238:7) E/flutter (12986): #18 StoreRefMixin.add (package:sembast/src/store_ref_impl.dart:72:25) E/flutter (12986): #19 ParentDao.insert (package:json_serial_test/data/parent_dao.dart:17:24) E/flutter (12986): <asynchronous suspension> E/flutter (12986): #20
_MyHomePageState.build.<anonymous closure> (package:json_serial_test/main.dart:120:22) E/flutter (12986): #21
_InkResponseState._handleTap (package:flutter/src/material/ink_well.dart:706:14) E/flutter (12986):
#22 _InkResponseState.build.<anonymous closure> (package:flutter/src/material/ink_well.dart:789:36) E/flutter (12986):
#23 GestureRecognizer.invokeCallback (package:flutter/src/gestures/recognizer.dart:182:24) E/flutter (12986): #24 TapGestureRecognizer.handleTapUp (package:flutter/src/gestures/tap.dart:486:11) E/flutter (12986): #25 BaseTapGestureRecognizer._checkUp (package:flutter/src/gestures/tap.dart:264:5) E/flutter (12986): #26 BaseTapGestureRecognizer.acceptGesture (package:flutter/src/gestures/tap.dart:236:7) E/flutter (12986): #27 GestureArenaManager.sweep (package:flutter/src/gestures/arena.dart:156:27) E/flutter (12986):
#28 GestureBinding.handleEvent (package:flutter/src/gestures/binding.dart:222:20) E/flutter (12986):
#29 GestureBinding.dispatchEvent (package:flutter/src/gestures/binding.dart:198:22) E/flutter (12986):
#30 GestureBinding._handlePointerEvent (package:flutter/src/gestures/binding.dart:156:7) E/flutter (12986):
#31 GestureBinding._flushPointerEventQueue (package:flutter/src/gestures/binding.dart:102:7) E/flutter (12986):
#32 GestureBinding._handlePointerDataPacket (package:flutter/src/gestures/binding.dart:86:7) E/flutter (12986):
#33 _rootRunUnary (dart:async/zone.dart:1138:13) E/flutter (12986): #34 _CustomZone.runUnary (dart:async/zone.dart:1031:19) E/flutter (12986): #35 _CustomZone.runUnaryGuarded (dart:async/zone.dart:933:7) E/flutter (12986): #36 _invoke1 (dart:ui/hooks.dart:273:10) E/flutter (12986): #37
_dispatchPointerDataPacket (dart:ui/hooks.dart:182:5) E/flutter (12986):
如果有人可以帮助我显示我错过的,做错的事情,我将不胜感激。
原始帖子===============json_serializable
应该将类的全部转换为JSON,还是我遇到了限制?
我已决定尝试解决通过使用json_serializable
创建使用NoSQL DB
所需的toJson和fromJson方法导致的一系列问题。
如果我创建一个包含List<Ojb>
字段的类,则生成的代码似乎为该类的每个字段生成JSON,但对列表中的对象却不这样做。
简单示例
class Parent {
final int age;
final String name;
List<Child> children;
Parent({this.age, this.name, this.children});
}
class Child {
final int age;
final String name;
Child({this.age, this.name});
}
[当我使用json_serializable时,它看起来很不错,我为上述类获取了toJson和fromJson方法。乍看起来,一切看起来都很完美。
[当我尝试将父级(包含子级)插入我的NoSQL DB时,插入无法说不支持类型(引用子级对象)-True语句,对此没有任何问题。
当我通过调试器逐步执行此操作时,这就是我所看到的。
Parent
转换为地图年龄是价值的关键名称显示为键及其值
到目前为止,我可以看到所有内容都是地图[..看起来都很不错
然后我们进入子对象列表。
此部分未转换为映射,但仍作为子对象列表存在,因此插入失败。
两个类都具有jsonSerializable
批注这两个类都正在生成期望的代码(部分),类
只要我不尝试在我的一个课程中使用List<myObject>
,一切都可以正常运行。
使用诸如json_serializable之类的软件包的全部原因是依赖于自动生成的代码,而不必自己构建。我不想手动更新自动生成的代码来解决此问题,这就是为什么我没有粘贴代码。如果这是答案,那么我将采取其他方法。
我的问题是...是否缺少某些配置或可能做错了,即使该类的字段不仅仅是简单的int,也允许该类中的所有项目都转换为map / json。和字符串类型。我希望我可以有一个包含基元,对象,对象列表等的类,并且所有内容都应正确生成,否则就没有?
[经过许多次尝试和重建,我已经解决了这个问题,并且对于我的Sembast DB来说,现在一切正常,并且对我的模型类使用json_serializable可能还有其他因素促成了我的成功,但我认为主要区别是在Parent类的JSONSerializable注释中添加了以下参数。
explicitToJson:是
这里是代码,如果有帮助,可以帮助其他人。
@JsonSerializable(explicitToJson: true)
class Parent {
int id;
final String name;
final int age;
List<Child> children;
Job job;
Parent({this.name, this.age, this.children, this.job});
factory Parent.fromJson(Map<String, dynamic> json) => _$ParentFromJson(json);
Map<String, dynamic> toJson() => _$ParentToJson(this);
}