Unable to save extra properties in offline db which are not exists in remote table

[taddisateesh]

I've integrated the Community data sync client into our .NET MAUI app, and everything is functioning well. However, I'm encountering an issue with the offline sync table. Specifically, in the attached ConstructionDto file, I've added a new property that should be retained only in the offline table and not synced with the remote table. Is this possible? If so, could you please provide a solution?

FYI: This was working fine with old sdk. Reference link : https://github.com/Azure/azure-mobile-apps

• Server:

  • Version of dotnet being used to compile? 8.0.11
  • Library versions? - 8.0.6
  • What database are you using? - Azure
  • Where are you running the server? - Azure
  • GitHub repository containing the code (optional, but helps!)

• Client:

  • What platform (Android, iOS, Windows, etc.) versions are you running on? - Android and iOS
  • Does it happen in an emulator / simulator, or only on a real device? - both
  • Version of dotnet being used to compile? - 8.0.11
  • .NET Runtime Environment (WPF, UWP, WinUI3, MAUI, etc.): MAUI
  • Datsync Toolkit NuGet versions? 8.0.6
  • GitHub repository containing the code (optional, but helps!)

Do let me know if you require any additional details
Regrads,
Sateesh taddi.

[adrianhall]

There are two methods that you can use:

1. Put [JsonIgnore] on the property to remain local.
2. Create a new table with the local only properties and use [DoNotSynchronize] on the DbSet property in the context.

Of the two, (2) is preferred since it ensures that you can reset the table without destroying the local only data. In production, table resets are not unknown as a fix to missing data that can't be re-created except through a re-synchronization event.

[taddisateesh]

@adrianhall Thanks for your response.

For the first case, the property is simply ignored and is not being saved in the local database.

I will try to implement the second approach. However, with the old SDK (https://github.com/Azure/azure-mobile-apps), it used to save local-only properties in the local database along with remote properties without requiring a separate table

[adrianhall]

For the first case, - I think there is something else going on here. JsonIgnore does not affect what is happening via EF Core. It only affects serialization. Thus, it should not be ignored by EF Core. I've got explicit tests for this case, so there is something else happening with your code.

[taddisateesh]

Hey @adrianhall,

JsonIgnore works fine until we explicitly call PushAsync. However, the marked JsonIgnore property values reset when calling PullAsync after PushAsync

Here is sample code

  public async Task SaveItemAsync(T item, CancellationToken token = default(CancellationToken))
        {
            try
            {
                using (var dbContext = new AppDbContext(dbContextOptionsBuilder.Options))
                {
                    dbContext.TokenRequester = TokenRequester;
                    await ClearExistingQueue(dbContext, typeof(T));
                    if (item == null)
                    {
                        throw new ArgumentException(nameof(item));
                    }
                    ListAction action = (item.Id == null) ? ListAction.Add : ListAction.Update;
                    if (item.Id == null)
                    {
                        item.Id = Guid.NewGuid().ToString("N");
                        await dbContext.Set<T>().AddAsync(item, token);
                    }
                    else
                    {
                        dbContext.Set<T>().Update(item);
                    }
                    await dbContext.SaveChangesAsync();
                    await dbContext.Set<T>().PushAsync();
                }
            }
            catch(Exception ex)
            {
                Console.WriteLine(ex);
            }
            //ItemsUpdated?.Invoke(this, new RemoteServiceEventArgs<T>(action, item));
        }

[taddisateesh]

@adrianhall and one more thing CommunityToolkit.Datasync.Client ignores nested models and returns null values. Where as it used work Microsoft.Datasync.Client (https://github.com/Azure/azure-mobile-apps).

[adrianhall]

Microsoft.Datasync.Client never supported nested models. They worked by accident. Because of the move to EF Core for database access (instead of a direct SQlite system), we're explicitly not supporting nested models. The lack of support has been in the documentation for as long as I was managing Azure Mobile Apps (going on a decade now).

I'll work up a design for properly ignoring model properties.