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SteveSandersonMSSteveSandersonMS
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Add simpler prerendering API. Fixes aspnet#607 
1 parent 9cce26e commit 94fc84a

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Lines changed: 225 additions & 33 deletions

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‎samples/misc/NodeServicesExamples/Controllers/HomeController.cs‎

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using System.Threading.Tasks;
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using Microsoft.AspNetCore.Mvc;
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using Microsoft.AspNetCore.NodeServices;
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using Microsoft.AspNetCore.SpaServices.Prerendering;
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namespace NodeServicesExamples.Controllers
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{
@@ -34,6 +35,20 @@ public async Task<IActionResult> Chart([FromServices] INodeServices nodeServices
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return View();
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}
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public async Task<IActionResult> Prerendering([FromServices] ISpaPrerenderer prerenderer)
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{
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var result = await prerenderer.RenderToString("./Node/prerenderPage");
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if (!string.IsNullOrEmpty(result.RedirectUrl))
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{
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return Redirect(result.RedirectUrl);
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}
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ViewData["PrerenderedHtml"] = result.Html;
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ViewData["PrerenderedGlobals"] = result.CreateGlobalsAssignmentScript();
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return View();
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}
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public IActionResult Error()
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{
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return View("~/Views/Shared/Error.cshtml");

‎samples/misc/NodeServicesExamples/Node/prerenderPage.js‎

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var createServerRenderer = require('aspnet-prerendering').createServerRenderer;
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module.exports = createServerRenderer(function(params) {
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return new Promise(function (resolve, reject) {
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var message = 'The HTML was returned by the prerendering boot function. '
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+ 'The boot function received the following params:'
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+ '<pre>' + JSON.stringify(params, null, 4) + '</pre>';
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resolve({
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html: '<h3>Hello, world!</h3>' + message,
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globals: { sampleData: { nodeVersion: process.version } }
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});
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});
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});

‎samples/misc/NodeServicesExamples/NodeServicesExamples.csproj‎

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@@ -9,7 +9,7 @@
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</PropertyGroup>
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<ItemGroup>
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<ProjectReference Include="..\..\..\src\Microsoft.AspNetCore.NodeServices\Microsoft.AspNetCore.NodeServices.csproj" />
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<ProjectReference Include="..\..\..\src\Microsoft.AspNetCore.SpaServices\Microsoft.AspNetCore.SpaServices.csproj" />
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</ItemGroup>
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<ItemGroup>

‎samples/misc/NodeServicesExamples/Startup.cs‎

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@@ -17,6 +17,7 @@ public void ConfigureServices(IServiceCollection services)
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// Enable Node Services
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services.AddNodeServices();
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services.AddSpaPrerenderer();
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}
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// This method gets called by the runtime. Use this method to configure the HTTP request pipeline.

‎samples/misc/NodeServicesExamples/Views/Home/Index.cshtml‎

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@@ -9,4 +9,5 @@
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<ul>
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<li><a asp-action="ES2015Transpilation">ES2015 transpilation</a></li>
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<li><a asp-action="Chart">Server-side chart rendering</a></li>
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<li><a asp-action="Prerendering">Server-side SPA prerendering</a></li>
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</ul>

‎samples/misc/NodeServicesExamples/Views/Home/Prerendering.cshtml‎

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<h1>Server-side prerendering</h1>
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<p>
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This sample demonstrates how you can invoke a JavaScript module that contains
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prerendering logic for a Single-Page Application framework.
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</p>
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</p>
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Your prerendering boot function will receive parameters that describe the page
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being rendered and any data supplied by the .NET code. The return value should be
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a promise that resolves with data to be injected into the page, such as the
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rendered HTML and any global data that should be made available to client-side code.
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</p>
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@Html.Raw(ViewData["PrerenderedHtml"])
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<script>@Html.Raw(ViewData["PrerenderedGlobals"])</script>
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<script>
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// Demonstrates how client-side code can receive data from the prerendering process
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console.log('Received Node version from prerendering logic: ' + sampleData.nodeVersion);
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</script>

‎samples/misc/NodeServicesExamples/package.json‎

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"name": "nodeservicesexamples",
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"version": "0.0.0",
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"dependencies": {
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"aspnet-prerendering": "^2.0.6",
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"babel-core": "^6.7.4",
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"babel-preset-es2015": "^6.6.0",
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"node-chartist": "^1.0.2"

‎src/Microsoft.AspNetCore.SpaServices/Prerendering/DefaultSpaPrerenderer.cs‎

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using System.Threading;
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using Microsoft.AspNetCore.Hosting;
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using Microsoft.AspNetCore.Http;
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using Microsoft.AspNetCore.NodeServices;
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using System.Threading.Tasks;
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namespace Microsoft.AspNetCore.SpaServices.Prerendering
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{
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/// <summary>
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/// Default implementation of a DI service that provides convenient access to
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/// server-side prerendering APIs. This is an alternative to prerendering via
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/// the asp-prerender-module tag helper.
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/// </summary>
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internal class DefaultSpaPrerenderer : ISpaPrerenderer
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{
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private readonly string _applicationBasePath;
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private readonly CancellationToken _applicationStoppingToken;
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private readonly IHttpContextAccessor _httpContextAccessor;
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private readonly INodeServices _nodeServices;
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public DefaultSpaPrerenderer(
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INodeServices nodeServices,
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IApplicationLifetime applicationLifetime,
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IHostingEnvironment hostingEnvironment,
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IHttpContextAccessor httpContextAccessor)
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{
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_applicationBasePath = hostingEnvironment.ContentRootPath;
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_applicationStoppingToken = applicationLifetime.ApplicationStopping;
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_httpContextAccessor = httpContextAccessor;
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_nodeServices = nodeServices;
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}
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public Task<RenderToStringResult> RenderToString(
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string moduleName,
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string exportName = null,
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object customDataParameter = null,
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int timeoutMilliseconds = default(int))
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{
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return Prerenderer.RenderToString(
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_applicationBasePath,
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_nodeServices,
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_applicationStoppingToken,
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new JavaScriptModuleExport(moduleName) { ExportName = exportName },
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_httpContextAccessor.HttpContext,
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customDataParameter,
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timeoutMilliseconds);
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}
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}
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}

‎src/Microsoft.AspNetCore.SpaServices/Prerendering/ISpaPrerenderer.cs‎

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using System.Threading.Tasks;
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namespace Microsoft.AspNetCore.SpaServices.Prerendering
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{
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/// <summary>
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/// Represents a service that can perform server-side prerendering for
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/// JavaScript-based Single Page Applications. This is an alternative
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/// to using the 'asp-prerender-module' tag helper.
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/// </summary>
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public interface ISpaPrerenderer
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{
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/// <summary>
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/// Invokes JavaScript code to perform server-side prerendering for a
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/// Single-Page Application. This is an alternative to using the
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/// 'asp-prerender-module' tag helper.
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/// </summary>
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/// <param name="moduleName">The JavaScript module that exports a prerendering function.</param>
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/// <param name="exportName">The name of the export from the JavaScript module, if it is not the default export.</param>
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/// <param name="customDataParameter">An optional JSON-serializable object to pass to the JavaScript prerendering function.</param>
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/// <param name="timeoutMilliseconds">If specified, the prerendering task will time out after this duration if not already completed.</param>
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/// <returns></returns>
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Task<RenderToStringResult> RenderToString(
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string moduleName,
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string exportName = null,
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object customDataParameter = null,
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int timeoutMilliseconds = default(int));
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}
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}

‎src/Microsoft.AspNetCore.SpaServices/Prerendering/PrerenderTagHelper.cs‎

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using System;
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using System.Text;
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using System.Threading;
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using System.Threading.Tasks;
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using Microsoft.AspNetCore.Hosting;
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using Microsoft.AspNetCore.Http.Features;
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using Microsoft.AspNetCore.Mvc.ViewFeatures;
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using Microsoft.AspNetCore.Mvc.Rendering;
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using Microsoft.AspNetCore.NodeServices;
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using Microsoft.AspNetCore.Razor.TagHelpers;
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using Newtonsoft.Json;
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namespace Microsoft.AspNetCore.SpaServices.Prerendering
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{
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/// <returns>A <see cref="Task"/> representing the operation.</returns>
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public override async Task ProcessAsync(TagHelperContext context, TagHelperOutput output)
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{
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// We want to pass the original, unencoded incoming URL data through to Node, so that
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// server-side code has the same view of the URL as client-side code (on the client,
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// location.pathname returns an unencoded string).
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// The following logic handles special characters in URL paths in the same way that
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// Node and client-side JS does. For example, the path "/a=b%20c" gets passed through
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// unchanged (whereas other .NET APIs do change it - Path.Value will return it as
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// "/a=b c" and Path.ToString() will return it as "/a%3db%20c")
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var requestFeature = ViewContext.HttpContext.Features.Get<IHttpRequestFeature>();
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var unencodedPathAndQuery = requestFeature.RawTarget;
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var request = ViewContext.HttpContext.Request;
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var unencodedAbsoluteUrl = $"{request.Scheme}://{request.Host}{unencodedPathAndQuery}";
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var result = await Prerenderer.RenderToString(
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_applicationBasePath,
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_nodeServices,
@@ -111,11 +95,9 @@ public override async Task ProcessAsync(TagHelperContext context, TagHelperOutpu
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{
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ExportName = ExportName
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},
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unencodedAbsoluteUrl,
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unencodedPathAndQuery,
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ViewContext.HttpContext,
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CustomDataParameter,
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TimeoutMillisecondsParameter,
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request.PathBase.ToString());
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TimeoutMillisecondsParameter);
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if (!string.IsNullOrEmpty(result.RedirectUrl))
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{
@@ -134,19 +116,10 @@ public override async Task ProcessAsync(TagHelperContext context, TagHelperOutpu
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// Also attach any specified globals to the 'window' object. This is useful for transferring
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// general state between server and client.
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if (result.Globals != null)
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var globalsScript = result.CreateGlobalsAssignmentScript();
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if (!string.IsNullOrEmpty(globalsScript))
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{
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var stringBuilder = new StringBuilder();
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foreach (var property in result.Globals.Properties())
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{
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stringBuilder.AppendFormat("window.{0} = {1};",
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property.Name,
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property.Value.ToString(Formatting.None));
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}
146-
if (stringBuilder.Length > 0)
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{
148-
output.PostElement.SetHtmlContent($"<script>{stringBuilder}</script>");
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}
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output.PostElement.SetHtmlContent($"<script>{globalsScript}</script>");
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}
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}
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}

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