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Copy pathPrerenderTagHelper.cs
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117 lines (101 loc) · 5.16 KB
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using System;
using System.Text;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Hosting;
using Microsoft.AspNetCore.Http.Features;
using Microsoft.AspNetCore.Mvc.ViewFeatures;
using Microsoft.AspNetCore.Mvc.Rendering;
using Microsoft.AspNetCore.NodeServices;
using Microsoft.AspNetCore.Razor.TagHelpers;
using Newtonsoft.Json;
namespace Microsoft.AspNetCore.SpaServices.Prerendering
{
[HtmlTargetElement(Attributes = PrerenderModuleAttributeName)]
public class PrerenderTagHelper : TagHelper
{
private const string PrerenderModuleAttributeName = "asp-prerender-module";
private const string PrerenderExportAttributeName = "asp-prerender-export";
private const string PrerenderWebpackConfigAttributeName = "asp-prerender-webpack-config";
private const string PrerenderDataAttributeName = "asp-prerender-data";
private const string PrerenderTimeoutAttributeName = "asp-prerender-timeout";
private static INodeServices _fallbackNodeServices; // Used only if no INodeServices was registered with DI
private readonly string _applicationBasePath;
private readonly INodeServices _nodeServices;
public PrerenderTagHelper(IServiceProvider serviceProvider)
{
var hostEnv = (IHostingEnvironment) serviceProvider.GetService(typeof(IHostingEnvironment));
_nodeServices = (INodeServices) serviceProvider.GetService(typeof(INodeServices)) ?? _fallbackNodeServices;
_applicationBasePath = hostEnv.ContentRootPath;
// Consider removing the following. Having it means you can get away with not putting app.AddNodeServices()
// in your startup file, but then again it might be confusing that you don't need to.
if (_nodeServices == null)
{
_nodeServices = _fallbackNodeServices = NodeServicesFactory.CreateNodeServices(
new NodeServicesOptions(serviceProvider));
}
}
[HtmlAttributeName(PrerenderModuleAttributeName)]
public string ModuleName { get; set; }
[HtmlAttributeName(PrerenderExportAttributeName)]
public string ExportName { get; set; }
[HtmlAttributeName(PrerenderWebpackConfigAttributeName)]
public string WebpackConfigPath { get; set; }
[HtmlAttributeName(PrerenderDataAttributeName)]
public object CustomDataParameter { get; set; }
[HtmlAttributeName(PrerenderTimeoutAttributeName)]
public int TimeoutMillisecondsParameter { get; set; }
[HtmlAttributeNotBound]
[ViewContext]
public ViewContext ViewContext { get; set; }
public override async Task ProcessAsync(TagHelperContext context, TagHelperOutput output)
{
// We want to pass the original, unencoded incoming URL data through to Node, so that
// server-side code has the same view of the URL as client-side code (on the client,
// location.pathname returns an unencoded string).
// The following logic handles special characters in URL paths in the same way that
// Node and client-side JS does. For example, the path "/a=b%20c" gets passed through
// unchanged (whereas other .NET APIs do change it - Path.Value will return it as
// "/a=b c" and Path.ToString() will return it as "/a%3db%20c")
var requestFeature = ViewContext.HttpContext.Features.Get<IHttpRequestFeature>();
var unencodedPathAndQuery = requestFeature.RawTarget;
var request = ViewContext.HttpContext.Request;
var unencodedAbsoluteUrl = $"{request.Scheme}://{request.Host}{unencodedPathAndQuery}";
var result = await Prerenderer.RenderToString(
_applicationBasePath,
_nodeServices,
new JavaScriptModuleExport(ModuleName)
{
ExportName = ExportName,
WebpackConfig = WebpackConfigPath
},
unencodedAbsoluteUrl,
unencodedPathAndQuery,
CustomDataParameter,
TimeoutMillisecondsParameter);
if (!string.IsNullOrEmpty(result.RedirectUrl))
{
// It's a redirection
ViewContext.HttpContext.Response.Redirect(result.RedirectUrl);
return;
}
// It's some HTML to inject
output.Content.SetHtmlContent(result.Html);
// Also attach any specified globals to the 'window' object. This is useful for transferring
// general state between server and client.
if (result.Globals != null)
{
var stringBuilder = new StringBuilder();
foreach (var property in result.Globals.Properties())
{
stringBuilder.AppendFormat("window.{0} = {1};",
property.Name,
property.Value.ToString(Formatting.None));
}
if (stringBuilder.Length > 0)
{
output.PostElement.SetHtmlContent($"<script>{stringBuilder}</script>");
}
}
}
}
}