Offline sync in wasm

[FrederikFBrandt]

I remember reading that Blazor WASM offline sync isn't supported. I have however put my sqlite db file into the browser cache as base64. My application cannot rely on getting live data every single time a user starts up the wasm client, but it is ok for a full refresh whenever a user decides to clear cache. My solution is working, it feels snappy and it's reliable. My question is, how come it isn't officially supported? Is that a big issue or risk I haven't thought of?

[adrianhall]

There are many many things that can break, to the point where we can't control all the variables.

If it is working for you - great! However, that's a different story than "official support".

[tanudhawan]

I read this comment on the thread which says the documentation and samples are yet to be updated but wasm offline sync is supported. Can you pls throw some light to help me understand better. Thanks :)

[adrianhall]

The docs will say "we support online operations only - offline is not available"

[tanudhawan]

Thanks Adrian, I tried using the datasync toolkit with bit.besql database for Blazor Webassembly PWA- It integrates well with the Push operations but pull operation is failing as the PullRequestBuilder is using MD5 which isn't supported in browser. Are there any plans to extend this library to offer support for bit.besql (the library supports both mobile and PWA apps).

[adrianhall]

I'm not familiar with bit.besql and we only deal with dotnet - what happens in the WASM side isn't something we test (hence why Blazor is only supported with online facilities).

I have no intent on adding support for bit.besql. Happy to work with you on testing, etc. - perhaps you can start by creating a new test suite for bit.besql based on the existing client tests and see what breaks.

[MysterDru]

@FrederikFBrandt I have come up with a solution for using the toolkit in WASM as well, similar to your approach.

However, when it comes to doing data syncing, custom pull request operations do not work unless I specify a custom query id for every operation. As @tanudhawan stated, under the covers the toolkit uses MD5 hashing for creating the query id automatically which isn't supported in WASM. This can be avoided though if a custom id is set for every operation.

Note, i'm not using wasm for a production application, its being uses as a more rapid development app target when building a Blazor Hybrid MAUI application and to allow devs on our team to work on the project without having the mobile tooling setup.

[FrederikFBrandt]

I don't have issues with query id - I use pull / push, but not custom ones, so that could be the reason?

However - I do use a custom table controller: public abstract class CustomTableController<T1,T2> : TableController where T1 : EntityTableData, ITableData

where I do some overrides and configure stuff as my base for all tables. I did an override on DeleteAsync for example, before the delete changes were implemented in the latest patches:

public override async Task<IActionResult> DeleteAsync([FromRoute] string id, CancellationToken cancellationToken = default)
{
    try
    {
        return await base.DeleteAsync(id, cancellationToken);
    }
    catch (HttpException ex)
    {

        if(ex.StatusCode == 410)
        {
            // If the item is already deleted, we return NoContent, no harm done in accepting that an item that should be deleted is already deleted.
            return NoContent();
        }
        return StatusCode(ex.StatusCode, ex.Message);
    }
}