Counter.razor

@page "/counter"

@implements IDisposable

@using System.Linq;
@using System.Threading
@using System.Reactive.Linq;

<h1>Counter</h1>

<p>Current count: @State?.Count</p>

<button class="btn btn-primary" @onclick="CounterService.Increment">Increment</button>
<button class="btn btn-primary" @onclick="CounterService.Decrement">Decrement</button>

<h4 class="mt-2 mb-2">Exception handling</h4>

<button class="btn mb-2 btn-warning" @onclick="ThrowException">Throw Exception</button>

<pre>@ExceptionInfo</pre>

@code {
    [Inject] ICounterService CounterService { get; set; }

    private CounterState State { get; set; }
    private IDisposable StateSubscription { get; set; }

    private string ExceptionInfo { get; set; }

    protected override void OnInitialized()
    {
        var asyncState = CounterService.SubscribeAsync();
        var state = asyncState.ToObservable();

        StateSubscription = state.Subscribe(async state =>
        {
            State = state;
            await InvokeAsync(() => StateHasChanged());
        });
    }

    private async Task ThrowException()
    {
        try
        {
            await CounterService.ThrowException();
        }
        catch (Grpc.Core.RpcException ex)
        {
            ExceptionInfo = $"RpcException: {ex.Status}";
        }
    }

    public void Dispose()
    {
        StateSubscription?.Dispose();
    }
}