Question 179768 in Flutter Question posted in
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Flutter – firebase_database/unknown : Could not convert Error

I’m trying to send data to a Firebase Realtime database, but when I’m trying to write I get an error that says [firebase_database/unknown] Could not convert.

Here is the stack tree:

[firebase_database/unknown] Could not convert

dart-sdk/lib/_internal/js_dev_runtime/private/ddc_runtime/errors.dart 288:49      throw_
packages/firebase_database_web/src/interop/utils/utils.dart 92:5                  jsify
packages/firebase_database_web/src/interop/utils/utils.dart 80:36                 <fn>
dart-sdk/lib/_internal/js_dev_runtime/private/linked_hash_map.dart 21:13          forEach
packages/firebase_database_web/src/interop/utils/utils.dart 79:15                 jsify
packages/firebase_database_web/src/interop/database.dart 142:53                   set
packages/firebase_database_web/src/database_reference_web.dart 51:23              set
dart-sdk/lib/_internal/js_dev_runtime/patch/async_patch.dart 84:54                runBody
dart-sdk/lib/_internal/js_dev_runtime/patch/async_patch.dart 123:5                _async
packages/firebase_database_web/src/database_reference_web.dart 49:19              set
packages/firebase_database/src/database_reference.dart 73:22                      set
packages/ziique/FireService/RealtimeData/fire_beatIt_realtime_service.dart 34:23  createSession
dart-sdk/lib/_internal/js_dev_runtime/patch/async_patch.dart 45:50                <fn>
dart-sdk/lib/async/zone.dart 1661:54                                              runUnary
dart-sdk/lib/async/future_impl.dart 147:18                                        handleValue
dart-sdk/lib/async/future_impl.dart 784:44                                        handleValueCallback
dart-sdk/lib/async/future_impl.dart 813:13                                        _propagateToListeners
dart-sdk/lib/async/future_impl.dart 584:5                                         [_completeWithValue]
dart-sdk/lib/async/future_impl.dart 657:7                                         callback
dart-sdk/lib/async/schedule_microtask.dart 40:11                                  _microtaskLoop
dart-sdk/lib/async/schedule_microtask.dart 49:5                                   _startMicrotaskLoop
dart-sdk/lib/_internal/js_dev_runtime/patch/async_patch.dart 177:15               <fn>

And here is my code:

DatabaseReference ref = FirebaseDatabase.instance.ref();
  var uuid = const Uuid();
  List<User> users = [];
  int timeschanged = 0;
  int timesplayed = 0;
  int versionID = 1;

  Future<void> createSession(Beat beat, User host) async {
    String id = uuid.v4();
    try {
      BeatItSession beatItSession = BeatItSession(
          sessionid: id,
          usersadded: users,
          creationTime: DateTime.now(),
          lastModified: DateTime.now(),
          beatString: beat.beatString,
          timeschanged: timeschanged,
          timesplayed: timesplayed,
          hostID: host.uid,
          versionid: versionID);
      final sessionRef = ref.child("beatItSessions").child(id);
      print(beatItSession.toMap());
      print(ref.path);
      await sessionRef.set(beatItSession.toMap());
    } catch (e) {
      if (kDebugMode) {
        print(e);
      }
    }
  }

I have edited the rules on firebase to allow all read.
I have also tried to write manual json code with a simple name and still got the error.
I have tried giving the ref a path but got the same issue.

How can I solve this?

Tags:

2

Answers


  1. Chosen as BEST ANSWER
    0

    I Have just figured out the cause of the error. Objects. Firebase realtime does not like Objects.

    soo my list with objects could not exists. had to use thier ID´s instead.


  2. 0

    Firebase Realtime Database is a NoSQL database that stores data in a hierarchical JSON-like structure – so the above error will come up when you try save a non-JSON-like object.

    All your objects need to be converted to JSON – freezed is a popular code generating package that is used to model data and it enables json conversions with the help of json_serializable. In your case it could look something like this:

    part 'beat_it_session.model.freezed.dart';
part 'beat_it_session.model.g.dart';

@freezed
class BeatItSessionModel with _$BeatItSessionModel {
  const BeatItSessionModel._();

  const factory BeatItSessionModel({
    required String sessionID,
    @Default([]) List<UserModel> users,
    DateTime creationTime,
    DateTime lastModified,
    String? beatString,
    @Default({}) Map<String, dynamic> timeschanged,
    @Default({}) Map<String, dynamic> timesplayed,
    required String hostID,
    required String versionid,
  }) = _BeatItSessionModel;


  // ** OBJECT CONVERSIONS
  factory BeatItSessionModel.fromJson(Map<String, dynamic> json) =>
  _$BeatItSessionModelFromJson(json);

  Map<String, dynamic> toSnapshot() => toJson()
   ..update('users', (_) => users.map((user) => user.toJson()).toList());
}

    There are many tutorials to help you set it up, such as this one.

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