protected async Task ExecuteAsync(
ViewContext viewContext,
string?contentType,
int?statusCode)
{
if (viewContext == null)
{
throw new ArgumentNullException(nameof(viewContext));
}
var response = viewContext.HttpContext.Response;
ResponseContentTypeHelper.ResolveContentTypeAndEncoding(
contentType,
response.ContentType,
(DefaultContentType, Encoding.UTF8),
MediaType.GetEncoding,
out var resolvedContentType,
out var resolvedContentTypeEncoding);
response.ContentType = resolvedContentType;
if (statusCode != null)
{
response.StatusCode = statusCode.Value;
}
OnExecuting(viewContext);
await using (var writer = WriterFactory.CreateWriter(response.Body, resolvedContentTypeEncoding))
{
var view = viewContext.View;
var oldWriter = viewContext.Writer;
try
{
viewContext.Writer = writer;
DiagnosticListener.BeforeView(view, viewContext);
await view.RenderAsync(viewContext);
DiagnosticListener.AfterView(view, viewContext);
}
finally
{
viewContext.Writer = oldWriter;
}
// Perf: Invoke FlushAsync to ensure any buffered content is asynchronously written to the underlying
// response asynchronously. In the absence of this line, the buffer gets synchronously written to the
// response as part of the Dispose which has a perf impact.
await writer.FlushAsync();
}
}