Problems with Deleting Record with Realm for React Native

[s1tony]

When I attempt to delete a record, my app instantly crashes and I cannot seem to catch the exception. From the MongoDB support team, it seems the context is being closed too soon. Any idea what is happening? This happens whether I use a listener or not.

Delete method:

  const deleteList = (listId: string): void => {
    const listRealm = realmRef.current;
    const list = listRealm?.objectForPrimaryKey<List>("List", new ObjectId(listId));
    try {
      listRealm?.write<void>(() => {
        if (list) {
          listRealm?.delete(list);
        }
      })
    } catch(error) {
      console.log(error);
    }
  };

React Native 0.70

SDK: android vRealmJS/10.21.1 Platform Version: 31

MongoDB version 5.0.12

[ianpward]

Hi can you please provide the Device Sync AppId so we can take a look on the backend logs? Thank you

[s1tony]

Hi Ian,

listmaker-luqgq

Also, I am utilizing Flexible Sync.

Thank you so much,

Tony

[ianpward]

@s1tony looks like your access token is expired and you're not refreshing it. Not sure why but try re-authenticating

[ianpward]

You should be able to see this in the client-side logs if you have the logger enabled I believe?

[s1tony]

I need to enable the logger, I believe. I am not understanding why I can do everything but delete and not be authenticated? Perhap I am misunderstanding?

On Mon, Sep 26, 2022 at 11:26 AM Ian Ward @.***> wrote:

You should be able to see this in the client-side logs if you have the logger enabled I believe?

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[ianpward]

you should see it here - https://www.mongodb.com/docs/realm-sdks/js/latest/Realm.App.Sync.html#~LogLevel

[s1tony]

Thanks - will try this afternoon

[s1tony]

I setup logging and it logs fine until I try the delete and then the app crashes and no more logging :(.

[s1tony]

Just before the app crashes:

[s1tony]

Is this the culprit:

"Order Matters

In collection notification handlers, always apply changes in the following order: deletions, insertions, then modifications. Handling insertions before deletions may result in unexpected behavior."

[s1tony]

I just explored the above by removing the listener before the delete and the issue still occurs.

This is the exception from the MongoDB logs:

integrating changesets failed: retryable error while committing integrated changesets: failed to apply changesets: failed to insert into history: connection(listcluster-shard-00-02.mewf8.mesh.mongodb.net:30558[-41158]) incomplete read of message header: context canceled (ProtocolErrorCode=201)

[kraenhansen]

@s1tony are you registering any listeners on List collection or any objects containing the object you're deleting?

If so, can you catch any errors if you try-catch in those listener callback functions? You might be hitting https://github.com/realm/realm-js/issues/2654

[s1tony]

Yes, I did have listeners on the List collection. In fact, I was just doing some testing of adding and deleting from the List collection without the listeners and things seem to be working. As I recall, I could not catch any exceptions in the listener callback functions, but can try again.

Thanks for the feedback.

[s1tony]

Hmmm, the App crashed, as it did before, and I was not able to catch with a try-catch.

I reckon I will have to rewrite the code without the use is a listener 👎

[s1tony]

OK, so more test results. Listener or not, the issue arises when I add a List and then delete the List. No exception, no logs, just App crash:

Logs:

integrating changesets failed: retryable error while committing integrated changesets: error getting latest server version: connection(listcluster-shard-00-02.mewf8.mesh.mongodb.net:30558[-76754]) incomplete read of message header: context canceled (ProtocolErrorCode=201)

[s1tony]

I added react-native-exception-handler and still cannot catch the exception - the App just quits. I am out of ideas at this point and would really appreciate any ideas, thoughts or recommendations.

[kraenhansen]

What host machine are you developing on? I'm asking to determine what NDK might be used when compiling the app, specifically if you're on an Apple M1 / aarch64 and hitting this branch of the RN template: https://github.com/facebook/react-native/blob/v0.70.0/template/android/build.gradle#L12

Could I get you to share the output of running from the root of your repository?

npx react-native info

[s1tony]

info Fetching system and libraries information... System: OS: Windows 10 10.0.19044 CPU: (16) x64 11th Gen Intel(R) Core(TM) i7-11700K @ 3.60GHz Memory: 18.01 GB / 31.83 GB Binaries: Node: 14.18.0 - C:\Program Files\nodejs\node.EXE Yarn: Not Found npm: 8.9.0 - C:\Program Files\nodejs\npm.CMD Watchman: Not Found SDKs: Android SDK: Not Found Windows SDK: Not Found IDEs: Android Studio: AI-212.5712.43.2112.8609683 Visual Studio: Not Found Languages: Java: javac 17 - C:\Program Files\Common Files\Oracle\Java\javapath\javac.EXE npmPackages: @react-native-community/cli: Not Found react: 18.1.0 => 18.1.0 react-native: 0.70.1 => 0.70.1 react-native-windows: Not Found npmGlobalPackages: react-native: Not Found

[s1tony]

I am willing to build and test the library locally, if there is any way I can debug while it is running, in order to catch this "uncatchable error". I would just need some help and instructions on how to do so. I use VS for work, so I can install it on my home machine and utilize the C++ code.

On Sun, Oct 2, 2022 at 3:27 PM Kræn Hansen @.***> wrote:

What host machine are you developing on? I'm asking to determine what NDK might be used when compiling the app, specifically if you're on an Apple M1 / aarch64 and hitting this branch of the RN template: https://github.com/facebook/react-native/blob/v0.70.0/template/android/build.gradle#L12

Could I get you to share the output of running from the root of your repository?

npx react-native info

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[kneth]

@s1tony We need to investigate a bit more. Out of curiosity, which Android version do you target?

[s1tony]

I think 31 - but will verify and let you know.

On Tue, Oct 4, 2022 at 7:34 AM Kenneth Geisshirt @.***> wrote:

@s1tony https://github.com/s1tony We need to investigate a bit more. Out of curiosity, which Android version do you target?

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[s1tony]

Pretty sure 31

On Tue, Oct 4, 2022, 7:37 AM Tony Schilling @.***> wrote:

I think 31 - but will verify and let you know.

On Tue, Oct 4, 2022 at 7:34 AM Kenneth Geisshirt @.***> wrote:

@s1tony https://github.com/s1tony We need to investigate a bit more. Out of curiosity, which Android version do you target?

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[kneth]

@s1tony We are currently investigating the ticket, and I hope that I will be able to come with an update early next week.

[s1tony]

Hi guys, I think I have made some headway. After thinking about this some more and reviewing my code, it sure seems to have something to do with listeners. After a list is added, the app routes to a details page, which display the list items - and instantiates two listeners. One is on List and the other on ListItems, which is an embedded type within List.

A quick test seemed to confirm this as the cause. I will do some more testing and see if I can find another way to implement this page. Since users can share lists, I wanted the List Items to be updated if another user made a change.

[s1tony]

Unfortunately, it seems if I have a listener on the List or ListItems object at any time - even if I remove the listener before the delete - and try to delete - the app will crash.

Doesn't this pretty much deem listeners useless for me? This is very frustrating and very much limits what I can do.

[kraenhansen]

@s1tony can you share the code for the callback you're adding as a listener on these collections? And did you try my suggestion of adding a try-catch block around the entire body of those listener callbacks?

If you for example add this callback:

items.addListener(() => {
  // Some of your code, which might throw
});

it would turn into

items.addListener(() => {
  try {
    // Some of your code, which might throw
  } catch (err) {
    console.error(err);
  }
});

[s1tony]

Hi, I thought I had taken your suggestion at one time, but am losing track now. However, today I was going down the road of trying to remove the listener(s) before doing the delete, which was having inconsistent results.

I just tried your suggestion within my attempt to remove the listener upon the page losing focus. Anyway, here is a snippet of my now messy code:

` useFocusEffect( useCallback(() => { const item = listData.getList(listId); setList(item); //item?.listItems.addListener(listItemUpdateListener);

  item?.listItems.addListener((listItems) => {
    try {
      setListItems(getListItems(listItems));  
    } catch (err) {
      console.error(err);
    }
  });

  console.log('Add event listener');
  //item?.addListener(listUpdateListener);

  return () => {
    console.log('Remove event listener');
    //item?.listItems.removeListener(listItemUpdateListener);

    item?.listItems.removeListener((listItems) => {
      try {
        setListItems(getListItems(listItems));  
      } catch (err) {
        console.error(err);
      }
    });

    //item?.removeListener(listUpdateListener);
  };
}, [])

); `

Here is what I received:

This makes sense, I guess - except I thought removing the listener would take care of this.

I reckon my journey continues.

[s1tony]

I think what I tried originally after your suggestion was to put the try/catch in the callback method:

`  const listsUpdateListener = (lists: Realm.Collection<List & Realm.Object>) => {
    try {
      const items: IBaseList[] = [];

      lists?.forEach(t => {
        items.push({ _id: t._id, date: t.date, name: `${t.name}`, userId: t.userId, ownsList: t.userId === currentUser?.id});   
      });

      setLists(items);
    } catch(ex) {
      console.error(ex);
    }
  };
`

and then

listRawData?.removeListener(listsUpdateListener);

[s1tony]

It sure seems as though it was the listener on my details page, not the list page, and so my attempts to catch the exception were not successful because I was trying to catch on the list page.

With the try/catch on the details page, I can catch the exception and continue.

I feel as though I went round and round, getting lost trying different things - and for this I apologize.

[danieltabacaru]

@s1tony do you have a stack trace and/or full client logs?

[s1tony]

Yes, I will get what I can for you, as I can cause this exception to happen at will.

On Mon, Oct 10, 2022 at 9:32 AM Daniel Tabacaru @.***> wrote:

@s1tony https://github.com/s1tony do you have a stack trace and/or full client logs?

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[s1tony]

I don't have a full stack trace, but let me see what I can do.

From the logs:

[s1tony]

Yes, the exception is the following:

[Error: Access to invalidated Collection object]

What is happening is I have a listener on the embedded ListItems array within List in a detailed page. When I add a List, the application goes to this page where details (List Items) can be added. Then when I go to the Lists page and try to delete this List, the exception occurs.

While this makes sense, what is frustrating is I tried to remove the listener when leaving the page, but the exception still occurs.

[s1tony]

I think we have everything straightened out, for the most part. It seems that even if a listener is removed, it may not be completely removed. The code updates I made to handle this are as follows:

`  const listItemUpdateListener = (listItems: Realm.Collection<ListItem>) => {
    try {
      if (listItems.isValid()) {
        setListItems(getListItems(listItems));  
      }
    } catch(err) {
      console.error(err);
    }
  };
`