Blazor Server EF Core Cancelation - entity-framework-core

Question

In my app I have to be able to cancel uploads, I tried with threads cancelation but nothing happens, I think it is because I use DBContextFactory and I create a context for each uploaded file.
So I did this to save files in DB:
private async Task OnFilesDropped(FileUploadModel upload)
{
Uploads.Add(upload);
if (string.IsNullOrEmpty(upload.Error))
{
using var context = DbFactory.CreateDbContext();
upload.Context = context;
context.FileUploads.Add(upload);
upload.UploadCompletion = 45;
await context.SaveChangesAsync();
upload.UploadCompletion = 100;
}
}
and this in case of deleting a uploaded/uploading file:
private async Task DeleteUpload(FileUploadModel upload)
{
Uploads.Remove(upload);
await UploadsChanged.InvokeAsync(Uploads);
if (string.IsNullOrEmpty(upload.Error))
{
if (upload.UploadCompletion != 100)
{
await upload.Context.DisposeAsync();
}
else
{
using var context = DbFactory.CreateDbContext();
context.FileUploads.Remove(upload);
await context.SaveChangesAsync();
}
}
}
This way works because I dispose of the context, but I wonder if there is a better way of doing this? or if this solution could be problematic somehow?
Best Regards.

Answer 1

You should use a CancellationToken.
The SaveChangesAsync method on your context has an overload that can be provided a cancellationToken.
await context.SaveChangesAsync(cancellationToken);
If you already have a CancellationToken higher in the call stack, you can just pass that one down. Otherwise, you can create a CancellationTokenSource and use that to generate a cancellation token and then cancel it when appropriate.