ReactiveUI async freezes

Question

I am making some Avalonia MVVM app.

When the 'Log In' button is pressed, it looks in the database to see if the account matches, and this operation takes about 1 second. So in order to not freeze the UI for one second, I used await/async :

Login command:

private async Task loginCommand()
{
      //see if it exists in db
      using (var dbcontext = new DatabaseContext())
      {
          var user = await dbcontext.Credentials.FirstOrDefaultAsync(u => u.Email == this.Email);

          if (user == null)
          {
              //email not found
              await ShowErrorEmail();
              return;
          }

          if (user.Password != this.Password)
          {
              // incorrect password    
              await ShowErrorPassword();
              return;
          }

          //good to go
      }
}

Command definition:

var isInputValid = this.WhenAnyValue(x => x.Email, x => x.Password,
     (email, password) => (!string.IsNullOrWhiteSpace(password)
     && !string.IsNullOrWhiteSpace(email)));
     
LoginCommand = ReactiveCommand.CreateFromTask(loginCommand , isInputValid);

I debugged and found out that FirstOrDefaultAsync() takes about 1 second, but I awaited it so I have no idea why the UI freezes. Thanks!

Answer 1

Some database providers, such as SQLite, do not actually support async operations, so all the ...Async() calls are actually synchronous. If you're using such database provider, as a workaround you could wrap each call in a Task.Run().