输入'列表<dynamic> ' 不是类型 'List 的子类型<expense> ？ 在类型转换中</expense></dynamic>

Question

I use Hive to store daily expenses inside expenseBox like this:

final String now = DateFormat('yyyyMMdd').format(DateTime.now());
List<Expense> todaysExpenses = Hive.box<List<Expense>>('expenses').get(now, defaultValue: []) as List<Expense>;
todaysExpenses.add(expense);
expenseBox.put(now, todaysExpenses);

When I add a new expense to the expenseBox everything works fine and my expenses are displayed correctly. But as soon as I hot restart I get the following error.

This is my code for displaying My List of Expenses.

import 'package:flutter/material.dart';
import 'package:hive_flutter/hive_flutter.dart';
import 'package:intl/intl.dart';

import '/models/expense.dart';
import '/screens/add_expense_screen.dart';

class HomeScreen extends StatefulWidget {
  const HomeScreen({Key? key}) : super(key: key);

  static const routeName = '/home_page';

  @override
  _HomeScreenState createState() => _HomeScreenState();
}

class _HomeScreenState extends State<HomeScreen> {
  late Box expenseBox;
  late Box pocketBox;

  List<Expense> mapped = [];

  @override
  void initState() {
    expenseBox = Hive.box<List<Expense>>('expenses');
    pocketBox = Hive.box<int>('pocket');
    super.initState();
  }

  @override
  Widget build(BuildContext context) {
    return ValueListenableBuilder(
      valueListenable: Hive.box<int>('pocket').listenable(),
      builder: (context, Box<int> pocketBox, child) => Scaffold(
        appBar: AppBar(
          title: const Text('Expense Tracker'),
          elevation: 0,
          centerTitle: true,
        ),
        body: NestedScrollView(
          headerSliverBuilder: (context, _) => [
            SliverAppBar(
              expandedHeight: MediaQuery.of(context).size.height * 0.15,
              flexibleSpace: FlexibleSpaceBar(
                background: Container(
                  padding: const EdgeInsets.symmetric(horizontal: 10),
                  child: Row(
                    children: [
                      Expanded(
                        child: Column(
                          mainAxisSize: MainAxisSize.min,
                          children: [
                            Row(
                              mainAxisAlignment: MainAxisAlignment.spaceBetween,
                              children: [
                                const Text(
                                  'Expense Tracker',
                                  style: TextStyle(
                                      fontSize: 14, color: Colors.white),
                                ),
                                Text(
                                  '${pocketBox.get('budget') ?? 0}',
                                  style: const TextStyle(
                                      fontSize: 18,
                                      color: Colors.white,
                                      fontWeight: FontWeight.bold),
                                ),
                              ],
                            ),
                            Row(
                              mainAxisAlignment: MainAxisAlignment.spaceBetween,
                              children: [
                                const Text(
                                  'Income',
                                  style: TextStyle(
                                      fontSize: 14, color: Colors.white),
                                ),
                                Text(
                                  '${pocketBox.get('totalIncome') ?? 0}',
                                  style: const TextStyle(
                                      fontSize: 18,
                                      color: Colors.white,
                                      fontWeight: FontWeight.bold),
                                ),
                              ],
                            ),
                            Row(
                              mainAxisAlignment: MainAxisAlignment.spaceBetween,
                              children: [
                                const Text(
                                  'Expense',
                                  style: TextStyle(
                                      fontSize: 14, color: Colors.white),
                                ),
                                Text(
                                  '${pocketBox.get('totalExpense') ?? 0}',
                                  style: const TextStyle(
                                      fontSize: 18,
                                      color: Colors.white,
                                      fontWeight: FontWeight.bold),
                                ),
                              ],
                            ),
                          ],
                        ),
                      ),
                      Expanded(child: Container()),
                    ],
                  ),
                ),
              ),
            ),
          ],
          body: ValueListenableBuilder(
            valueListenable: Hive.box<List<Expense>>('expenses').listenable(),
            builder: (context, Box<List<Expense>> expensesBox, child) {
              return ListView.separated(
                separatorBuilder: (context, index) {
                  return const SizedBox(height: 20);
                },
                itemCount: expenseBox.length,
                itemBuilder: (ctx, ind) {
                  final expense = expenseBox.getAt(ind) as List<Expense>;
                  return SizedBox(
                    height: 200,
                    child: ListView.builder(
                      itemCount: expenseBox.getAt(ind).length,
                      itemBuilder: (context, index) {
                        return ListTile(
                          title: Text(expense[index].name),
                          subtitle: Text(DateFormat('yyyyMMdd').format(expense[index].date)),
                        );
                      },
                    ),
                  );
                },
              );
            },
          ),
        ),
        floatingActionButton: FloatingActionButton(
            onPressed: () {
              Navigator.of(context).push(MaterialPageRoute(
                builder: (_) => const AddExpenseScreen(
                  index: -1,
                ),
              ));
            },
            child: const Icon(Icons.add)),
      ),
    );
  }
}

This is the whole error code

type 'List<dynamic>' is not a subtype of type 'List<Expense>?' in type cast

When the exception was thrown, this was the stack: 
#0      BoxImpl.getAt (package:hive/src/box/box_impl.dart:57:41)
#1      _HomeScreenState.build.<anonymous closure>.<anonymous closure>.<anonymous closure> (package:expense_tracker/screens/home_screen.dart:123:46)
#2      new ListView.separated.<anonymous closure> (package:flutter/src/widgets/scroll_view.dart:1260:34)
#3      SliverChildBuilderDelegate.build (package:flutter/src/widgets/sliver.dart:457:22)
#4      SliverMultiBoxAdaptorElement._build (package:flutter/src/widgets/sliver.dart:1215:28)
#5      SliverMultiBoxAdaptorElement.createChild.<anonymous closure> (package:flutter/src/widgets/sliver.dart:1228:55)
#6      BuildOwner.buildScope (package:flutter/src/widgets/framework.dart:2531:19)
#7      SliverMultiBoxAdaptorElement.createChild (package:flutter/src/widgets/sliver.dart:1221:12)
#8      RenderSliverMultiBoxAdaptor._createOrObtainChild.<anonymous closure> (package:flutter/src/rendering/sliver_multi_box_adaptor.dart:349:23)
#9      RenderObject.invokeLayoutCallback.<anonymous closure> (package:flutter/src/rendering/object.dart:1962:59)
#10     PipelineOwner._enableMutationsToDirtySubtrees (package:flutter/src/rendering/object.dart:910:15)
#11     RenderObject.invokeLayoutCallback (package:flutter/src/rendering/object.dart:1962:14)
#12     RenderSliverMultiBoxAdaptor._createOrObtainChild (package:flutter/src/rendering/sliver_multi_box_adaptor.dart:338:5)
#13     RenderSliverMultiBoxAdaptor.addInitialChild (package:flutter/src/rendering/sliver_multi_box_adaptor.dart:422:5)
#14     RenderSliverList.performLayout (package:flutter/src/rendering/sliver_list.dart:79:12)
#15     RenderObject.layout (package:flutter/src/rendering/object.dart:1852:7)
#16     RenderSliverEdgeInsetsPadding.performLayout (package:flutter/src/rendering/sliver_padding.dart:137:12)
#17     RenderSliverPadding.performLayout (package:flutter/src/rendering/sliver_padding.dart:371:11)
#18     RenderObject.layout (package:flutter/src/rendering/object.dart:1852:7)
#19     RenderViewportBase.layoutChildSequence (package:flutter/src/rendering/viewport.dart:510:13)
#20     RenderViewport._attemptLayout (package:flutter/src/rendering/viewport.dart:1580:12)
#21     RenderViewport.performLayout (package:flutter/src/rendering/viewport.dart:1489:20)
#22     RenderObject.layout (package:flutter/src/rendering/object.dart:1852:7)
#23     RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:116:14)
#24     RenderObject.layout (package:flutter/src/rendering/object.dart:1852:7)
#25     RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:116:14)
#26     RenderObject.layout (package:flutter/src/rendering/object.dart:1852:7)
#27     RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:116:14)
#28     RenderObject.layout (package:flutter/src/rendering/object.dart:1852:7)
#29     RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:116:14)
#30     RenderObject.layout (package:flutter/src/rendering/object.dart:1852:7)
#31     RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:116:14)
#32     RenderObject.layout (package:flutter/src/rendering/object.dart:1852:7)
#33     RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:116:14)
#34     RenderObject.layout (package:flutter/src/rendering/object.dart:1852:7)
#35     RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:116:14)
#36     RenderObject.layout (package:flutter/src/rendering/object.dart:1852:7)
#37     RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:116:14)
#38     RenderCustomPaint.performLayout (package:flutter/src/rendering/custom_paint.dart:545:11)
#39     RenderObject.layout (package:flutter/src/rendering/object.dart:1852:7)
#40     RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:116:14)
#41     RenderObject.layout (package:flutter/src/rendering/object.dart:1852:7)
#42     RenderSliverFillRemainingWithScrollable.performLayout (package:flutter/src/rendering/sliver_fill.dart:92:14)
#43     RenderObject.layout (package:flutter/src/rendering/object.dart:1852:7)
#44     RenderViewportBase.layoutChildSequence (package:flutter/src/rendering/viewport.dart:510:13)
#45     RenderViewport._attemptLayout (package:flutter/src/rendering/viewport.dart:1580:12)
#46     RenderViewport.performLayout (package:flutter/src/rendering/viewport.dart:1489:20)
#47     RenderObject.layout (package:flutter/src/rendering/object.dart:1852:7)
#48     RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:116:14)
#49     RenderObject.layout (package:flutter/src/rendering/object.dart:1852:7)
#50     RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:116:14)
#51     RenderObject.layout (package:flutter/src/rendering/object.dart:1852:7)
#52     RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:116:14)
#53     RenderObject.layout (package:flutter/src/rendering/object.dart:1852:7)
#54     RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:116:14)
#55     RenderObject.layout (package:flutter/src/rendering/object.dart:1852:7)
#56     RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:116:14)
#57     RenderObject.layout (package:flutter/src/rendering/object.dart:1852:7)
#58     RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:116:14)
#59     RenderObject.layout (package:flutter/src/rendering/object.dart:1852:7)
#60     RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:116:14)
#61     RenderObject.layout (package:flutter/src/rendering/object.dart:1852:7)
#62     RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:116:14)
#63     RenderCustomPaint.performLayout (package:flutter/src/rendering/custom_paint.dart:545:11)
#64     RenderObject.layout (package:flutter/src/rendering/object.dart:1852:7)
#65     RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:116:14)
#66     RenderObject.layout (package:flutter/src/rendering/object.dart:1852:7)
#67     MultiChildLayoutDelegate.layoutChild (package:flutter/src/rendering/custom_layout.dart:171:12)
#68     _ScaffoldLayout.performLayout (package:flutter/src/material/scaffold.dart:1005:7)
#69     MultiChildLayoutDelegate._callPerformLayout (package:flutter/src/rendering/custom_layout.dart:240:7)
#70     RenderCustomMultiChildLayoutBox.performLayout (package:flutter/src/rendering/custom_layout.dart:403:14)
#71     RenderObject.layout (package:flutter/src/rendering/object.dart:1852:7)
#72     RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:116:14)
#73     RenderObject.layout (package:flutter/src/rendering/object.dart:1852:7)
#74     RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:116:14)
#75     _RenderCustomClip.performLayout (package:flutter/src/rendering/proxy_box.dart:1376:11)
#76     RenderObject.layout (package:flutter/src/rendering/object.dart:1852:7)
#77     RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:116:14)
#78     RenderObject.layout (package:flutter/src/rendering/object.dart:1852:7)
#79     RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:116:14)
#80     RenderObject.layout (package:flutter/src/rendering/object.dart:1852:7)
#81     RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:116:14)
#82     RenderObject.layout (package:flutter/src/rendering/object.dart:1852:7)
#83     RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:116:14)
#84     RenderObject.layout (package:flutter/src/rendering/object.dart:1852:7)
#85     RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:116:14)
#86     RenderObject.layout (package:flutter/src/rendering/object.dart:1852:7)
#87     RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:116:14)
#88     RenderObject.layout (package:flutter/src/rendering/object.dart:1852:7)
#89     RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:116:14)
#90     RenderObject.layout (package:flutter/src/rendering/object.dart:1852:7)
#91     RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:116:14)
#92     RenderObject.layout (package:flutter/src/rendering/object.dart:1852:7)
#93     RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:116:14)
#94     RenderOffstage.performLayout (package:flutter/src/rendering/proxy_box.dart:3428:13)
#95     RenderObject.layout (package:flutter/src/rendering/object.dart:1852:7)
#96     RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:116:14)
#97     RenderObject.layout (package:flutter/src/rendering/object.dart:1852:7)
#98     _RenderTheatre.performLayout (package:flutter/src/widgets/overlay.dart:751:15)
#99     RenderObject.layout (package:flutter/src/rendering/object.dart:1852:7)
#100    RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:116:14)
#101    RenderObject.layout (package:flutter/src/rendering/object.dart:1852:7)
#102    RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:116:14)
#103    RenderObject.layout (package:flutter/src/rendering/object.dart:1852:7)
#104    RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:116:14)
#105    RenderObject.layout (package:flutter/src/rendering/object.dart:1852:7)
#106    RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:116:14)
#107    RenderObject.layout (package:flutter/src/rendering/object.dart:1852:7)
#108    RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:116:14)
#109    RenderObject.layout (package:flutter/src/rendering/object.dart:1852:7)
#110    RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:116:14)
#111    RenderObject.layout (package:flutter/src/rendering/object.dart:1852:7)
#112    RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:116:14)
#113    RenderObject.layout (package:flutter/src/rendering/object.dart:1852:7)
#114    RenderView.performLayout (package:flutter/src/rendering/view.dart:165:14)
#115    RenderObject._layoutWithoutResize (package:flutter/src/rendering/object.dart:1707:7)
#116    PipelineOwner.flushLayout (package:flutter/src/rendering/object.dart:879:18)
#117    RendererBinding.drawFrame (package:flutter/src/rendering/binding.dart:497:19)
#118    WidgetsBinding.drawFrame (package:flutter/src/widgets/binding.dart:883:13)
#119    RendererBinding._handlePersistentFrameCallback (package:flutter/src/rendering/binding.dart:363:5)
#120    SchedulerBinding._invokeFrameCallback (package:flutter/src/scheduler/binding.dart:1145:15)
#121    SchedulerBinding.handleDrawFrame (package:flutter/src/scheduler/binding.dart:1082:9)
#122    SchedulerBinding.scheduleWarmUpFrame.<anonymous closure> (package:flutter/src/scheduler/binding.dart:863:7)

Answer 1

Hive can handle primitive data types well as stated in the documents https://docs.hivedb.dev/#/custom-objects/type_adapters

But it does not know much about the type of the serialized data you've stored in the previous sessions. It will be able to handle the live data correctly during the session, since the live data is defined, created and stored as is in the memory at the time. But after serialization and deserialization in some other session, it'll not be able to guess the type from the contents beyond the primitive types.

You'll have to create type adapters for your data types for hive to handle them correctly or you could cast the deserialized data manually to your own types.