Prerendering logic supplies PathBase (formatted as baseUrl) to boot logic

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

@@ -119,7 +119,8 @@ namespace Microsoft.AspNetCore.SpaServices.Prerendering
                 unencodedAbsoluteUrl,
                 unencodedPathAndQuery,
                 CustomDataParameter,
-                TimeoutMillisecondsParameter);
+                TimeoutMillisecondsParameter,
+                request.PathBase.ToString());
 
             if (!string.IsNullOrEmpty(result.RedirectUrl))
             {

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

@@ -30,6 +30,7 @@ namespace Microsoft.AspNetCore.SpaServices.Prerendering
         /// <param name="requestPathAndQuery">The path and query part of the URL of the currently-executing HTTP request. This is supplied to the prerendering code.</param>
         /// <param name="customDataParameter">An optional JSON-serializable parameter to be supplied to the prerendering code.</param>
         /// <param name="timeoutMilliseconds">The maximum duration to wait for prerendering to complete.</param>
+        /// <param name="requestPathBase">The PathBase for the currently-executing HTTP request.</param>
         /// <returns></returns>
         public static Task<RenderToStringResult> RenderToString(
             string applicationBasePath,
@@ -38,7 +39,8 @@ namespace Microsoft.AspNetCore.SpaServices.Prerendering
             string requestAbsoluteUrl,
             string requestPathAndQuery,
             object customDataParameter,
-            int timeoutMilliseconds)
+            int timeoutMilliseconds,
+            string requestPathBase)
         {
             return nodeServices.InvokeExportAsync<RenderToStringResult>(
                 NodeScript.Value.FileName,
@@ -48,7 +50,8 @@ namespace Microsoft.AspNetCore.SpaServices.Prerendering
                 requestAbsoluteUrl,
                 requestPathAndQuery,
                 customDataParameter,
-                timeoutMilliseconds);
+                timeoutMilliseconds,
+                requestPathBase);
         }
     }
 }

src/Microsoft.AspNetCore.SpaServices/npm/aspnet-prerendering/src/Prerendering.ts

@@ -7,7 +7,7 @@ import { run as domainTaskRun, baseUrl as domainTaskBaseUrl } from 'domain-task/
 const defaultTimeoutMilliseconds = 30 * 1000;
 
 export function createServerRenderer(bootFunc: BootFunc): RenderToStringFunc {
-    const resultFunc = (callback: RenderToStringCallback, applicationBasePath: string, bootModule: BootModuleInfo, absoluteRequestUrl: string, requestPathAndQuery: string, customDataParameter: any, overrideTimeoutMilliseconds: number) => {
+    const resultFunc = (callback: RenderToStringCallback, applicationBasePath: string, bootModule: BootModuleInfo, absoluteRequestUrl: string, requestPathAndQuery: string, customDataParameter: any, overrideTimeoutMilliseconds: number, requestPathBase: string) => {
         // Prepare a promise that will represent the completion of all domain tasks in this execution context.
         // The boot code will wait for this before performing its final render.
         let domainTaskCompletionPromiseResolve;
@@ -19,6 +19,7 @@ export function createServerRenderer(bootFunc: BootFunc): RenderToStringFunc {
             location: url.parse(requestPathAndQuery),
             origin: parsedAbsoluteRequestUrl.protocol + '//' + parsedAbsoluteRequestUrl.host,
             url: requestPathAndQuery,
+            baseUrl: (requestPathBase || '') + '/',
             absoluteUrl: absoluteRequestUrl,
             domainTasks: domainTaskCompletionPromise,
             data: customDataParameter

src/Microsoft.AspNetCore.SpaServices/npm/aspnet-prerendering/src/PrerenderingInterfaces.d.ts

@@ -23,6 +23,7 @@ interface BootFuncParams {
     location: any;              // e.g., Location object containing information '/some/path'
     origin: string;             // e.g., 'https://example.com:1234'
     url: string;                // e.g., '/some/path'
+    baseUrl: string;            // e.g., '' or '/myVirtualDir'
     absoluteUrl: string;        // e.g., 'https://example.com:1234/some/path'
     domainTasks: Promise<any>;
     data: any;                  // any custom object passed through from .NET