/// <summary>
/// Disposes the host asynchronously.
/// </summary>
/// <returns>A <see cref="ValueTask"/> which respresents the completion of disposal.</returns>
public async ValueTask DisposeAsync()
{
if (_disposed)
{
return;
}
_disposed = true;
_renderer?.Dispose();
if (_scope is IAsyncDisposable asyncDisposableScope)
{
await asyncDisposableScope.DisposeAsync();
}
else
{
_scope?.Dispose();
}
if (_services is IAsyncDisposable asyncDisposableServices)
{
await asyncDisposableServices.DisposeAsync();
}
else if (_services is IDisposable disposableServices)
{
disposableServices.Dispose();
}
}
public Task StartAsync(CancellationToken cancellationToken = default)
{
// We need to do this as early as possible, it eliminates a bunch of problems. Note that what we do
// is a bit fragile. If you see things breaking because JSRuntime.Current isn't set, then it's likely
// that something on the startup path went wrong.
//
// We want to the JSRuntime created here to be the 'ambient' runtime when JS calls back into .NET. When
// this happens in the browser it will be a direct call from Mono. We effectively needs to set the
// JSRuntime in the 'root' execution context which implies that we want to do as part of a direct
// call from Program.Main, and before any 'awaits'.
JSRuntime.SetCurrentJSRuntime(_runtime);
SetBrowserHttpMessageHandlerAsDefault();
var scopeFactory = Services.GetRequiredService <IServiceScopeFactory>();
_scope = scopeFactory.CreateScope();
try
{
var startup = _scope.ServiceProvider.GetService <IBlazorStartup>();
if (startup == null)
{
var message =
$"Could not find a registered Blazor Startup class. " +
$"Using {nameof(IWebAssemblyHost)} requires a call to {nameof(IWebAssemblyHostBuilder)}.UseBlazorStartup.";
throw new InvalidOperationException(message);
}
// Note that we differ from the WebHost startup path here by using a 'scope' for the app builder
// as well as the Configure method.
var builder = new WebAssemblyBlazorApplicationBuilder(_scope.ServiceProvider);
startup.Configure(builder, _scope.ServiceProvider);
_renderer = builder.CreateRenderer();
}
catch
{
_scope.Dispose();
_scope = null;
if (_renderer != null)
{
_renderer.Dispose();
_renderer = null;
}
throw;
}
return(Task.CompletedTask);
}
public Task StopAsync(CancellationToken cancellationToken = default)
{
if (_scope != null)
{
_scope.Dispose();
_scope = null;
}
if (_renderer != null)
{
_renderer.Dispose();
_renderer = null;
}
return(Task.CompletedTask);
}
private async Task StartAsyncAwaited()
{
var scopeFactory = Services.GetRequiredService <IServiceScopeFactory>();
_scope = scopeFactory.CreateScope();
try
{
var startup = _scope.ServiceProvider.GetService <IBlazorStartup>();
if (startup == null)
{
var message =
$"Could not find a registered Blazor Startup class. " +
$"Using {nameof(IWebAssemblyHost)} requires a call to {nameof(IWebAssemblyHostBuilder)}.UseBlazorStartup.";
throw new InvalidOperationException(message);
}
// Note that we differ from the WebHost startup path here by using a 'scope' for the app builder
// as well as the Configure method.
var builder = new WebAssemblyBlazorApplicationBuilder(_scope.ServiceProvider);
startup.Configure(builder, _scope.ServiceProvider);
_renderer = await builder.CreateRendererAsync();
}
catch
{
_scope.Dispose();
_scope = null;
if (_renderer != null)
{
_renderer.Dispose();
_renderer = null;
}
throw;
}
}