private async Task<StringCollectionTextWriter> RenderPageAsync(IRazorPage page,
ViewContext context,
bool executeViewStart)
{
var bufferedWriter = new StringCollectionTextWriter(context.Writer.Encoding);
var writer = (TextWriter)bufferedWriter;
// The writer for the body is passed through the ViewContext, allowing things like HtmlHelpers
// and ViewComponents to reference it.
var oldWriter = context.Writer;
var oldFilePath = context.ExecutingFilePath;
context.Writer = writer;
context.ExecutingFilePath = page.Path;
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;
context.ExecutingFilePath = oldFilePath;
writer.Dispose();
}
}
// Partial support from HtmlHelperPartialExtensions.cs
public HtmlString Partial(string partialViewName)
{
using (var writer = new StringCollectionTextWriter(Encoding.UTF8))
{
RenderPartialCore(partialViewName, writer);
return new HtmlString(writer);
}
}
// Partial support from HtmlHelperPartialExtensions.cs
// Core code is in HtmlHelper.cs
public IHtmlContent Partial(string partialViewName)
{
using (var writer = new StringCollectionTextWriter(Encoding.UTF8))
{
RenderPartialCore(partialViewName, writer);
return writer.Content;
}
}
public async Task<IHtmlContent> PartialAsync(
[NotNull] string partialViewName)
{
using (var writer = new StringCollectionTextWriter(Encoding.UTF8))
{
await RenderPartialCoreAsync(partialViewName, writer);
return writer.Content;
}
}
private async Task RenderLayoutAsync(ViewContext context,
StringCollectionTextWriter 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))
{
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);
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();
}
await bodyWriter.CopyToAsync(context.Writer);
}
/// <summary>
/// Initializes a new instance of <see cref="HtmlString"/> that is backed by <paramref name="writer"/>.
/// </summary>
/// <param name="writer"></param>
public HtmlString([NotNull] StringCollectionTextWriter writer)
{
_writer = writer;
}