[Bug]: Update from V10 to V11 is not keeping existing user database

[Picao84]

Describe the bug 🐞

I have updated to V11 and while it finally works on MAUI on Android, it is not using the same database location used by V10. This is not an app with a cloud backend, so users will lose all their data! Can confirm the appName is exactly the same in both V10 and V11 code.

Step to reproduce

1 - Create an app with V10 and a simple CacheDatabase.UserAccount with a test object with one property with key "test".
2 - Launch the app and update the property value.
2 - Update the app with V11 and load data: it throws KeyNotFoundException.
3 - Reinstall the app with V10 and see that the test object is actually still there.

Reproduction repository

https://github.com/reactiveui/ReactiveUI

Expected behavior

V11 should pick up existing data from V10...

Screenshots 🖼️

No response

IDE

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Operating system

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Version

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Device

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ReactiveUI Version

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Additional information ℹ️

No response

[glennawatson]

There's examples in the docs of the conversion process and example program in the /src

It's expected behaviour.

[Picao84]

What conversion process? I followed the migration and this is what happens. I see nothing on conversion?

[Picao84]

I see the src folder with example code, but are we expected to have V10 and V11 simultaneously in the same app?

Edit - So to make the conversion I should launch a version of my app with V10 and copy the database to a V11 compatible directory? And then release another version with V11?

This is totally not clear and it's not anywhere I can find in the docs???

[glennawatson]

https://github.com/reactiveui/Akavache/blob/main/docs%2Fmigration-v10-to-v11.md

The data migration part

GitHub

Akavache/docs/migration-v10-to-v11.md at main · reactiveui/Akavache

An asynchronous, persistent key-value store created for writing desktop and mobile applications, based on SQLite3. Akavache is great for both storing important data as well as cached local data tha...

[Picao84]

You even have on the migration guide a section called "Testing your migration" with the comment "Test that old data is still available". There is not mention of a 'conversion' other than src folder?

[Picao84]

https://github.com/reactiveui/Akavache/blob/main/docs%2Fmigration-v10-to-v11.md

The data migration part

GitHub**Akavache/docs/migration-v10-to-v11.md at main · reactiveui/Akavache**An asynchronous, persistent key-value store created for writing desktop and mobile applications, based on SQLite3. Akavache is great for both storing important data as well as cached local data tha...

Yes, I followed that?

GitHub

Akavache/docs/migration-v10-to-v11.md at main · reactiveui/Akavache

An asynchronous, persistent key-value store created for writing desktop and mobile applications, based on SQLite3. Akavache is great for both storing important data as well as cached local data tha...

[glennawatson]

The old serializer is a bson one. So you use that serializer against the path of the old db. Then you can use writer as a example how to convert to v11 more efficient formats.

[Picao84]

Where exactly is that on the docs?

[glennawatson]

Also in terms of location you can manually specify location of the old db with the blobcache. Locations might be slightly different since we are using isolated storage now.

We can probably add a compatibility location helper which gets the old location if it helps.

[Picao84]

Yes, I imagine that would be helpful, otherwise this is really not fully backwards compatible is it?

[glennawatson]

Data Migration

Cross-Serializer Compatibility

V11.1 can read data written by V10.x and different serializers:

// This works! V11.1 can read V10.x data regardless of serializer choice var oldData = await CacheDatabase.UserAccount.GetObject("key_from_v10");

Gradual Migration

You can migrate serializers gradually:

// 1. Start with Newtonsoft for compatibility AppBuilder.CreateSplatBuilder() .WithAkavacheCacheDatabase(/* ... /); // 2. Later, change to System.Text.Json for performance // Old data will still be readable! AppBuilder.CreateSplatBuilder() .WithAkavacheCacheDatabase(/ ... */);

Platform-Specific Migration

.NET MAUI Migration

Before (V10.x):

public partial class App : Application { public App() { InitializeComponent(); BlobCache.ApplicationName = "MyMauiApp"; MainPage = new AppShell(); }

[Picao84]

I had already tried the Bson Serializer by the way. The problem is the location...

[Picao84]

I was able to access the old data through manual instance creation:

public class CustomCacheManager
{
private readonly IBlobCache _primaryCache;
private readonly IBlobCache _secondaryCache;

public CustomCacheManager()
{
    // Create specific cache instances for different purposes
    _primaryCache = new SqliteBlobCache(
        Path.Combine(Environment.GetFolderPath(Environment.SpecialFolder.LocalApplicationData), "userblobs.db"),
        new SystemJsonSerializer()
    );
    
    _secondaryCache = new InMemoryBlobCache(new SystemJsonSerializer());
}

}

[Picao84]

Could there be any potential downsides to do it this way? I guess I can just retrieve the existing data and then move it to the new instance.