Error while updating object property in flutter. Error code: 2005

MongoDB Atlas App Services & Realm Realm
,
1

Hello, I have a flutter project where I want to update an object property but I get this error:
Error: RealmException: Trying to modify database while in read transaction. Error code: 2005.

I tried all the documentation but still cannot solve the problem. Anyone can help me to solve it?

Here is my project: https://drive.google.com/file/d/1iDfK1m2AR2v1YfDeA3N-zptoKlJe9q4R/view?usp=sharing

2

Can you post the code that actually triggers the exception?

3

The exception says I’m trying to modify database while in read transaction, but db.isInTransaction here always output false.

  Future<void> updateFood(void Function() updateCallback) async {
    final db = await dbConn.realm;
    debugPrint(db.isInTransaction.toString());
    await db.writeAsync(updateCallback);
  }
4

The updateFood method calls writeAsync.

Future<void> updateFood(void Function() updateCallback) async {
    final db = await dbConn.realm;
    await db.writeAsync(updateCallback);
  }
5

Here is my code. Exception raised when this line is called:

foodsManager.allFoods[i].listOrder = i;

I want to update listOrder inside the onReorder event.

Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: const Text("Reorder"),
      ),
      body: SafeArea(
        child: Obx(
          () => ReorderableListView(
            onReorder: (oldIndex, newIndex) async {
              setState(() {
                final newIdx = newIndex > oldIndex ? newIndex - 1 : newIndex;
                final item = foodsManager.allFoods.removeAt(oldIndex);
                foodsManager.allFoods.insert(newIdx, item);
              });

              for (var i = 0; i < foodsManager.allFoods.length; i++) {
                await foodsManager.updateFood(() {
                  foodsManager.allFoods[i].listOrder = i;
                });
              }
            },
            children: foodsManager.allFoods
                .map(
                  (e) => ListTile(
                    key: Key(e.hashCode.toString()),
                    leading: ClipRRect(
                      borderRadius: BorderRadius.circular(10),
                      child: Container(
                        color: null,
                        height: 20,
                        width: 20,
                      ),
                    ),
                    title: Text(e.text!),
                    trailing: const Icon(Icons.reorder),
                    onTap: () {},
                  ),
                )
                .toList(),
          ),
        ),
      ),
    );
  }

And another weird thing is that when I read only one type of objects , the exception will not raise.


  RxList<FoodTag> allFoodTags = <FoodTag>[].obs;

  late final Future<List<FoodTag>> getTags = _getTags();
  Future<List<FoodTag>> _getTags() async {
    final db = await dbConn.realm;
    allFoodTags.clear();
    allFoodTags.addAll(db.all<FoodTag>());
    return allFoodTags;
  }


  RxList<FoodItem> allFoods = <FoodItem>[].obs;

  late final Future<List<FoodItem>> getFoods = _getFoods();
  Future<List<FoodItem>> _getFoods() async {
    final db = await dbConn.realm;
    allFoods.clear();
    allFoods.addAll(db.all<FoodItem>());
    allFoods.sort(
      (a, b) => a.listOrder.compareTo(b.listOrder),
    );
    return allFoods;
  }

 Widget build(BuildContext context) {
    final foodsManager = Get.put(FoodsManager());
    foodsManager.getFoods;
    final tagsManager = Get.put(TagsManager());
    tagsManager.getTags; //If i comment this line, the exception will gone.

    return MaterialApp(
      ...
      ...
    );
  }
6

Still cannot solve the problem.
Once I read two types of objects into list, the exception raises.
But if I read only one type of object from db, there will be no exception with the same update code.

7

Once I used realm with multiple schemas, this exception raises. Even set a single property. I’m already wrap my code in write or writeAsync method but the error keep saying I’m trying to modify property in read transaction. Need help.

8

The problem is that your code has a race condition, which leads to multiple realm instances getting opened. The race condition is in this code:

  Future<Realm> get realm async {
    if (_realm != null) {
      return _realm!;
    } else {
      _realm = await _initDB(notesDBFileName);
      return _realm!;
    }
  }

  Future<Realm> _initDB(String filePath) async {
    final dbPath = join(Configuration.defaultStoragePath, notesDBFileName);
    final config = Configuration.local(
      [FoodItem.schema, FoodTag.schema],
      path: dbPath,
      initialDataCallback: initData,
      shouldDeleteIfMigrationNeeded: kDebugMode,
    );
    return Realm(config);
  }

Because you only assigning _realm after the future resolves, there’s a brief window where db.realm is called twice and _realm is still null. That causes two different realm instances to get opened - then only one will start a write transaction, while the other will not. There’s no reason for _initDB to be a future, so if you convert it to a regular synchronous function, things work as expected.

9

Thanks very much, the problem is solved! And I will check all similar
async method calls.