Hive: Error when trying to retrieve list out of a box after hot-restart

[Flavsditz]

Steps to Reproduce
I am trying to store a complete list of objects in a box. I want to try and do that instead of iterating through all elements out of the box with box.values.toList().cast<MyObject>();. I would like to see if it would be better performance-wise at least.

So if I initially do the following:

1. Open the box
2. store a list inside the box
3. Directly afterwards try to retrieve the list out of the box
4. Print it

everything works and I get the expected result.
Now if I comment out step number 2 and hot reload, i.e. if I do the following:

1. Open the box
2. Retrieve the previously stored list out of the box
3. Print it

I get the following error:

E/flutter ( 7584): [ERROR:flutter/lib/ui/ui_dart_state.cc(148)] Unhandled Exception: type 'List<dynamic>' is not a subtype of type 'List<Foo>' in type cast
E/flutter ( 7584): #0      BoxImpl.get (package:hive/src/box/box_impl.dart:34:26)
E/flutter ( 7584): #1      initializeHive (package:[omitted]/main.dart:45:25)
E/flutter ( 7584): <asynchronous suspension>
E/flutter ( 7584): #2      main (package:[omitted]/main.dart:22:9)
E/flutter ( 7584): <asynchronous suspension>
E/flutter ( 7584): #3      _runMainZoned.<anonymous closure>.<anonymous closure> (dart:ui/hooks.dart:229:25)
E/flutter ( 7584): #4      _rootRun (dart:async/zone.dart:1124:13)
E/flutter ( 7584): #5      _CustomZone.run (dart:async/zone.dart:1021:19)
E/flutter ( 7584): #6      _runZoned (dart:async/zone.dart:1516:10)
E/flutter ( 7584): #7      runZoned (dart:async/zone.dart:1500:12)
E/flutter ( 7584): #8      _runMainZoned.<anonymous closure> (dart:ui/hooks.dart:221:5)
E/flutter ( 7584): #9      _startIsolate.<anonymous closure> (dart:isolate-patch/isolate_patch.dart:305:19)
E/flutter ( 7584): #10     _RawReceivePortImpl._handleMessage (dart:isolate-patch/isolate_patch.dart:172:12)

Code sample
Here is the Foo object:

import 'package:hive/hive.dart';
part 'foo.g.dart';
@HiveType()
class Foo extends HiveObject {
  @HiveField(0) final String id;
  Foo(this.id);
  @override
  String toString() {
    return 'Foo{id: $id}';
  }
}

The code for the storing:

 var fooBox = await Hive.openBox<List<Foo>>("Foo");
  var foos = [Foo("1"), Foo("2")];
  fooBox.put("foos", foos);
  var foosList = fooBox.get("foos", defaultValue: []);
  print(foosList);

and the code that throws the error

 var fooBox = await Hive.openBox<List<Foo>>("Foo");

  var foosList = fooBox.get("foos", defaultValue: []);
  print(foosList);

Version

• Platform: Android Emulator, Linux
• Flutter version: v1.9.1+hotfix.6 (Channel stable)
• Hive version: 1.1.1
• Hive Flutter version: 0.2.1
• Hive Generator version: 0.5.2

[leisim]

This is a limitation of Dart. Use the following:

var fooBox = await Hive.openBox<List<Foo>>("Foo");

var foosList = fooBox.get("foos", defaultValue: []).cast<Foo>();
print(foosList);

[Flavsditz]

I still get the same errors if I use the code you provided.

[leisim]

Sorry:

var fooBox = await Hive.openBox<List>("Foo");

var foosList = fooBox.get("foos", defaultValue: []).cast<Foo>();
print(foosList);

[Flavsditz]

That did the trick! Thanks for the info... I wouldn't have guessed that that was the case

[MaskyS]

I spent half a day trying to figure this bug out, solved thanks to this issue. @leisim Do the docs say anything about this?

[leisim]

@MaskyS

Do the docs say anything about this?

Yes, at the very bottom of this page. Maybe I should mention it at other places too...