c# - WPF ProgressBar usage when using Async/Await

Question

I have a very simple task that loads some data like so:

async Task<List<Invoice>> GetInvoices()
{
    var invoices = await Task.Run(() => db.Invoices.AsNoTracking().ToList());
    return invoices;
}

What would be the best way to use this with a progressbar? I don't need to get the percentage loaded (although that would be useful), I simply need to show/hide the progressbar at start and finish of loading data. Is there a way to create a completed or finished method perhaps?

I am very new to async/await so kid gloves please!

Answer 1

Assuming GetInvoices gets called in some UI event handler and there is some progress bar control called ProgressBar, it's really simple:

private async void OnButton1Click(..)
{
    ProgressBar.IsIndeterminate = true;
    var result = await GetInvoices();
    ProgressBar.IsIndeterminate = false; // Maybe hide it, too
    // TODO: Do stuff with result
}

If you want to show actual progress, take a look at Progress<T> and IProgress<T>.