private async Task RenderLayoutAsync(
ViewContext context,
IBufferedTextWriter bodyWriter)
{
// A layout page can specify another layout page. We'll need to continue
// looking for layout pages until they're no longer specified.
var previousPage = RazorPage;
var renderedLayouts = new List <IRazorPage>();
while (!string.IsNullOrEmpty(previousPage.Layout))
{
if (!bodyWriter.IsBuffering)
{
// Once a call to RazorPage.FlushAsync is made, we can no longer render Layout pages - content has
// already been written to the client and the layout content would be appended rather than surround
// the body content. Throwing this exception wouldn't return a 500 (since content has already been
// written), but a diagnostic component should be able to capture it.
var message = Resources.FormatLayoutCannotBeRendered(Path, nameof(Razor.RazorPage.FlushAsync));
throw new InvalidOperationException(message);
}
var layoutPage = GetLayoutPage(context, previousPage.Layout);
if (renderedLayouts.Count > 0 &&
renderedLayouts.Any(l => string.Equals(l.Path, layoutPage.Path, StringComparison.Ordinal)))
{
// If the layout has been previously rendered as part of this view, we're potentially in a layout
// rendering cycle.
throw new InvalidOperationException(
Resources.FormatLayoutHasCircularReference(previousPage.Path, layoutPage.Path));
}
// Notify the previous page that any writes that are performed on it are part of sections being written
// in the layout.
previousPage.IsLayoutBeingRendered = true;
layoutPage.PreviousSectionWriters = previousPage.SectionWriters;
layoutPage.RenderBodyDelegateAsync = bodyWriter.CopyToAsync;
bodyWriter = await RenderPageAsync(layoutPage, context, executeViewStart : false);
renderedLayouts.Add(layoutPage);
previousPage = layoutPage;
}
// Ensure all defined sections were rendered or RenderBody was invoked for page without defined sections.
foreach (var layoutPage in renderedLayouts)
{
layoutPage.EnsureRenderedBodyOrSections();
}
if (bodyWriter.IsBuffering)
{
// Only copy buffered content to the Output if we're currently buffering.
await bodyWriter.CopyToAsync(context.Writer);
}
}
private async Task RenderLayoutAsync(ViewContext context,
IBufferedTextWriter bodyWriter)
{
// A layout page can specify another layout page. We'll need to continue
// looking for layout pages until they're no longer specified.
var previousPage = RazorPage;
var unrenderedSections = new HashSet <string>(StringComparer.OrdinalIgnoreCase);
while (!string.IsNullOrEmpty(previousPage.Layout))
{
if (!bodyWriter.IsBuffering)
{
// Once a call to RazorPage.FlushAsync is made, we can no longer render Layout pages - content has
// already been written to the client and the layout content would be appended rather than surround
// the body content. Throwing this exception wouldn't return a 500 (since content has already been
// written), but a diagnostic component should be able to capture it.
var message = Resources.FormatLayoutCannotBeRendered("FlushAsync");
throw new InvalidOperationException(message);
}
var layoutPage = GetLayoutPage(context, previousPage.Layout);
// Notify the previous page that any writes that are performed on it are part of sections being written
// in the layout.
previousPage.IsLayoutBeingRendered = true;
layoutPage.PreviousSectionWriters = previousPage.SectionWriters;
layoutPage.RenderBodyDelegate = bodyWriter.CopyTo;
bodyWriter = await RenderPageAsync(layoutPage, context, executeViewStart : false);
// Verify that RenderBody is called
layoutPage.EnsureBodyWasRendered();
unrenderedSections.UnionWith(layoutPage.PreviousSectionWriters.Keys);
unrenderedSections.ExceptWith(layoutPage.RenderedSections);
previousPage = layoutPage;
}
// If not all sections are rendered, throw.
if (unrenderedSections.Any())
{
var sectionNames = string.Join(", ", unrenderedSections);
throw new InvalidOperationException(Resources.FormatSectionsNotRendered(sectionNames));
}
if (bodyWriter.IsBuffering)
{
// Only copy buffered content to the Output if we're currently buffering.
await bodyWriter.CopyToAsync(context.Writer);
}
}
private async Task <IBufferedTextWriter> RenderPageAsync(IRazorPage page,
ViewContext context,
bool executeViewStart)
{
var razorTextWriter = new RazorTextWriter(context.Writer, context.Writer.Encoding);
TextWriter writer = razorTextWriter;
IBufferedTextWriter bufferedWriter = razorTextWriter;
if (EnableInstrumentation)
{
writer = _pageExecutionFeature.DecorateWriter(razorTextWriter);
bufferedWriter = writer as IBufferedTextWriter;
if (bufferedWriter == null)
{
var message = Resources.FormatInstrumentation_WriterMustBeBufferedTextWriter(
nameof(TextWriter),
_pageExecutionFeature.GetType().FullName,
typeof(IBufferedTextWriter).FullName);
throw new InvalidOperationException(message);
}
}
// The writer for the body is passed through the ViewContext, allowing things like HtmlHelpers
// and ViewComponents to reference it.
var oldWriter = context.Writer;
context.Writer = writer;
try
{
if (executeViewStart)
{
// Execute view starts using the same context + writer as the page to render.
await RenderViewStartAsync(context);
}
await RenderPageCoreAsync(page, context);
return(bufferedWriter);
}
finally
{
context.Writer = oldWriter;
writer.Dispose();
}
}
private async Task RenderLayoutAsync(ViewContext context,
IBufferedTextWriter bodyWriter)
{
// A layout page can specify another layout page. We'll need to continue
// looking for layout pages until they're no longer specified.
var previousPage = _razorPage;
while (!string.IsNullOrEmpty(previousPage.Layout))
{
if (!bodyWriter.IsBuffering)
{
// Once a call to RazorPage.FlushAsync is made, we can no longer render Layout pages - content has
// already been written to the client and the layout content would be appended rather than surround
// the body content. Throwing this exception wouldn't return a 500 (since content has already been
// written), but a diagnostic component should be able to capture it.
var message = Resources.FormatLayoutCannotBeRendered("FlushAsync");
throw new InvalidOperationException(message);
}
var layoutPage = _pageFactory.CreateInstance(previousPage.Layout);
if (layoutPage == null)
{
var message = Resources.FormatLayoutCannotBeLocated(previousPage.Layout);
throw new InvalidOperationException(message);
}
// Notify the previous page that any writes that are performed on it are part of sections being written
// in the layout.
previousPage.IsLayoutBeingRendered = true;
layoutPage.PreviousSectionWriters = previousPage.SectionWriters;
layoutPage.RenderBodyDelegate = bodyWriter.CopyTo;
bodyWriter = await RenderPageAsync(layoutPage, context, executeViewStart: false);
// Verify that RenderBody is called, or that RenderSection is called for all sections
layoutPage.EnsureBodyAndSectionsWereRendered();
previousPage = layoutPage;
}
if (bodyWriter.IsBuffering)
{
// Only copy buffered content to the Output if we're currently buffering.
await bodyWriter.CopyToAsync(context.Writer);
}
}
private async Task RenderLayoutAsync(
ViewContext context,
IBufferedTextWriter bodyWriter)
{
// A layout page can specify another layout page. We'll need to continue
// looking for layout pages until they're no longer specified.
var previousPage = RazorPage;
var renderedLayouts = new List<IRazorPage>();
while (!string.IsNullOrEmpty(previousPage.Layout))
{
if (!bodyWriter.IsBuffering)
{
// Once a call to RazorPage.FlushAsync is made, we can no longer render Layout pages - content has
// already been written to the client and the layout content would be appended rather than surround
// the body content. Throwing this exception wouldn't return a 500 (since content has already been
// written), but a diagnostic component should be able to capture it.
var message = Resources.FormatLayoutCannotBeRendered(Path, nameof(Razor.RazorPage.FlushAsync));
throw new InvalidOperationException(message);
}
var layoutPage = GetLayoutPage(context, previousPage.Layout);
if (renderedLayouts.Count > 0 &&
renderedLayouts.Any(l => string.Equals(l.Path, layoutPage.Path, StringComparison.Ordinal)))
{
// If the layout has been previously rendered as part of this view, we're potentially in a layout
// rendering cycle.
throw new InvalidOperationException(
Resources.FormatLayoutHasCircularReference(previousPage.Path, layoutPage.Path));
}
// Notify the previous page that any writes that are performed on it are part of sections being written
// in the layout.
previousPage.IsLayoutBeingRendered = true;
layoutPage.PreviousSectionWriters = previousPage.SectionWriters;
layoutPage.RenderBodyDelegateAsync = bodyWriter.CopyToAsync;
bodyWriter = await RenderPageAsync(layoutPage, context, executeViewStart: false);
renderedLayouts.Add(layoutPage);
previousPage = layoutPage;
}
// Ensure all defined sections were rendered or RenderBody was invoked for page without defined sections.
foreach (var layoutPage in renderedLayouts)
{
layoutPage.EnsureRenderedBodyOrSections();
}
if (bodyWriter.IsBuffering)
{
// Only copy buffered content to the Output if we're currently buffering.
await bodyWriter.CopyToAsync(context.Writer);
}
}
private async Task RenderLayoutAsync(ViewContext context,
IBufferedTextWriter bodyWriter)
{
// A layout page can specify another layout page. We'll need to continue
// looking for layout pages until they're no longer specified.
var previousPage = RazorPage;
var unrenderedSections = new HashSet<string>(StringComparer.OrdinalIgnoreCase);
while (!string.IsNullOrEmpty(previousPage.Layout))
{
if (!bodyWriter.IsBuffering)
{
// Once a call to RazorPage.FlushAsync is made, we can no longer render Layout pages - content has
// already been written to the client and the layout content would be appended rather than surround
// the body content. Throwing this exception wouldn't return a 500 (since content has already been
// written), but a diagnostic component should be able to capture it.
var message = Resources.FormatLayoutCannotBeRendered("FlushAsync");
throw new InvalidOperationException(message);
}
var layoutPage = GetLayoutPage(context, previousPage.Layout);
// Notify the previous page that any writes that are performed on it are part of sections being written
// in the layout.
previousPage.IsLayoutBeingRendered = true;
layoutPage.PreviousSectionWriters = previousPage.SectionWriters;
layoutPage.RenderBodyDelegate = bodyWriter.CopyTo;
bodyWriter = await RenderPageAsync(layoutPage, context, executeViewStart: false);
// Verify that RenderBody is called
layoutPage.EnsureBodyWasRendered();
unrenderedSections.UnionWith(layoutPage.PreviousSectionWriters.Keys);
unrenderedSections.ExceptWith(layoutPage.RenderedSections);
previousPage = layoutPage;
}
// If not all sections are rendered, throw.
if (unrenderedSections.Any())
{
var sectionNames = string.Join(", ", unrenderedSections);
throw new InvalidOperationException(Resources.FormatSectionsNotRendered(sectionNames));
}
if (bodyWriter.IsBuffering)
{
// Only copy buffered content to the Output if we're currently buffering.
await bodyWriter.CopyToAsync(context.Writer);
}
}
