/// <summary>
/// Locates and renders a view specified by <see cref="ViewName"/>. If <see cref="ViewName"/> is <c>null</c>,
/// then the view name searched for is<c>"Default"</c>.
/// </summary>
/// <param name="context">The <see cref="ViewComponentContext"/> for the current component execution.</param>
/// <returns>A <see cref="Task"/> which will complete when view rendering is completed.</returns>
public async Task ExecuteAsync(ViewComponentContext context)
{
if (context == null)
{
throw new ArgumentNullException(nameof(context));
}
var viewEngine = ViewEngine ?? ResolveViewEngine(context);
var viewContext = context.ViewContext;
var isNullOrEmptyViewName = string.IsNullOrEmpty(ViewName);
ViewEngineResult result = null;
IEnumerable <string> originalLocations = null;
if (!isNullOrEmptyViewName)
{
// If view name was passed in is already a path, the view engine will handle this.
result = viewEngine.GetView(viewContext.ExecutingFilePath, ViewName, isMainPage: false);
originalLocations = result.SearchedLocations;
}
if (result == null || !result.Success)
{
// This will produce a string like:
//
// Components/Cart/Default
//
// The view engine will combine this with other path info to search paths like:
//
// Views/Shared/Components/Cart/Default.cshtml
// Views/Home/Components/Cart/Default.cshtml
// Areas/Blog/Views/Shared/Components/Cart/Default.cshtml
//
// This supports a controller or area providing an override for component views.
var viewName = isNullOrEmptyViewName ? DefaultViewName : ViewName;
var qualifiedViewName = string.Format(
CultureInfo.InvariantCulture,
ViewPathFormat,
context.ViewComponentDescriptor.ShortName,
viewName);
result = viewEngine.FindView(viewContext, qualifiedViewName, isMainPage: false);
}
var view = result.EnsureSuccessful(originalLocations).View;
using (view as IDisposable)
{
if (_diagnosticListener == null)
{
_diagnosticListener = viewContext.HttpContext.RequestServices.GetRequiredService <DiagnosticListener>();
}
_diagnosticListener.ViewComponentBeforeViewExecute(context, view);
var childViewContext = new ViewContext(
viewContext,
view,
ViewData ?? context.ViewData,
context.Writer);
await view.RenderAsync(childViewContext);
_diagnosticListener.ViewComponentAfterViewExecute(context, view);
}
}