Add react tag helper. Clean up code and make it more consistent.

Microsoft.AspNet.NodeServices.React/Content/Node/react-rendering.js

@@ -10,6 +10,26 @@ var origJsLoader = require.extensions['.js'];
 require.extensions['.js'] = loadViaBabel;
 require.extensions['.jsx'] = loadViaBabel;
 
+function findReactComponent(options) {
+    var resolvedPath = path.resolve(process.cwd(), options.moduleName);
+    var loadedModule = require(resolvedPath);
+    if (options.exportName) {
+        // If exportName is specified explicitly, use it
+        if (!(options.exportName in loadedModule)) {
+            throw new Error('The module "' + resolvedPath + '" has no export named "' + options.exportName + '"');
+        }
+        return loadedModule[options.exportName];
+    } else if (typeof loadedModule === 'function') {
+        // Otherwise, if the module itself is a function, assume that is the component 
+        return loadedModule;
+    } else if (typeof loadedModule.default === 'function') {
+        // Otherwise, if the module has a default export which is a function, assume that is the component
+        return loadedModule.default;
+    } else {
+        throw new Error('Cannot find React component, because no export name was specified, and the module "' + resolvedPath + '" has no default exported class.');
+    }
+}
+
 function loadViaBabel(module, filename) {
     // Assume that all the app's own code is ES2015+ (optionally with JSX), but that none of the node_modules are.
     // The distinction is important because ES2015+ forces strict mode, and it may break ES3/5 if you try to run it in strict
@@ -25,14 +45,8 @@ function loadViaBabel(module, filename) {
 
 module.exports = {
     renderToString: function(callback, options) {
-        var resolvedPath = path.resolve(process.cwd(), options.moduleName);
-        var requestedModule = require(resolvedPath);
-        var component = options.exportName ? requestedModule[options.exportName] : requestedModule; 
-        if (!component) {
-            throw new Error('The module "' + resolvedPath + '" has no export named "' + options.exportName + '"');
-        }
-        
-        var history = createMemoryHistory(options.baseUrl);
+        var component = findReactComponent(options);
+        var history = createMemoryHistory(options.requestUrl);
         var reactElement = React.createElement(component, { history: history });
         var html = ReactDOMServer.renderToString(reactElement);
         callback(null, html);

Microsoft.AspNet.NodeServices.React/ReactPrerenderTagHelper.cs

@@ -0,0 +1,49 @@
+using System;
+using System.Threading.Tasks;
+using Microsoft.AspNet.Razor.Runtime.TagHelpers;
+using Microsoft.AspNet.Http;
+using Microsoft.AspNet.Http.Extensions;
+
+namespace Microsoft.AspNet.NodeServices.React
+{
+    [HtmlTargetElement(Attributes = PrerenderModuleAttributeName)]
+    public class ReactPrerenderTagHelper : TagHelper
+    {
+        static INodeServices fallbackNodeServices; // Used only if no INodeServices was registered with DI
+        
+        const string PrerenderModuleAttributeName = "asp-react-prerender-module";
+        const string PrerenderExportAttributeName = "asp-react-prerender-export";
+        
+        [HtmlAttributeName(PrerenderModuleAttributeName)]
+        public string ModuleName { get; set; }
+        
+        [HtmlAttributeName(PrerenderExportAttributeName)]
+        public string ExportName { get; set; }
+
+        private IHttpContextAccessor contextAccessor;
+        private INodeServices nodeServices;
+
+        public ReactPrerenderTagHelper(IServiceProvider nodeServices, IHttpContextAccessor contextAccessor)
+        {
+            this.contextAccessor = contextAccessor;
+            this.nodeServices = (INodeServices)nodeServices.GetService(typeof (INodeServices)) ?? fallbackNodeServices;
+            
+            // 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 (this.nodeServices == null) {
+                this.nodeServices = fallbackNodeServices = Configuration.CreateNodeServices(NodeHostingModel.Http);
+            }
+        }
+
+        public override async Task ProcessAsync(TagHelperContext context, TagHelperOutput output)
+        {
+            var request = this.contextAccessor.HttpContext.Request;
+            var result = await ReactRenderer.RenderToString(
+                nodeServices: this.nodeServices,
+                componentModuleName: this.ModuleName,
+                componentExportName: this.ExportName,
+                requestUrl: request.Path + request.QueryString.Value);
+            output.Content.SetContentEncoded(result);
+        }
+    }
+}

Microsoft.AspNet.NodeServices.React/ReactRenderer.cs

@@ -12,15 +12,11 @@ namespace Microsoft.AspNet.NodeServices.React
             nodeScript = new StringAsTempFile(script); // Will be cleaned up on process exit
         }
         
-        public static Task<string> RenderToString(INodeServices nodeServices, string moduleName, string baseUrl) {
-            return RenderToString(nodeServices, moduleName, /* exportName */ null, baseUrl);
-        }
-        
-        public static async Task<string> RenderToString(INodeServices nodeServices, string moduleName, string exportName, string baseUrl) {
+        public static async Task<string> RenderToString(INodeServices nodeServices, string componentModuleName, string componentExportName, string requestUrl) {
             return await nodeServices.InvokeExport(nodeScript.FileName, "renderToString", new {
-                moduleName,
-                exportName,
-                baseUrl
+                moduleName = componentModuleName,
+                exportName = componentExportName,
+                requestUrl = requestUrl
             });
         }
     }

Microsoft.AspNet.NodeServices.React/project.json

@@ -1,5 +1,5 @@
 {
-  "version": "1.0.0-alpha3",
+  "version": "1.0.0-alpha4",
   "description": "Microsoft.AspNet.NodeServices.React Class Library",
   "authors": [
     "Microsoft"
@@ -25,7 +25,8 @@
     }
   },
   "dependencies": {
-    "Microsoft.AspNet.NodeServices": "1.0.0-alpha3"
+    "Microsoft.AspNet.NodeServices": "1.0.0-alpha3",
+    "Microsoft.AspNet.Mvc.TagHelpers": "6.0.0-beta8"
   },
   "resource": [
     "Content/**/*"