从 AspNetCore TestHost 运行时编译 Razor 期间出现 CompilationFailedException

Question

我有 ASP.Net MVC 应用程序，其中一部分是将 Razor 视图编译为字符串。该代码与此示例非常相似： https://long2know.com/2017/08/rendering-and-emailing-embedded-razor-views-with-net-core/

我在 Startup.cs 中以这种方式注册了 Razor 引擎：

var viewAssembly = typeof(HtmlGeneratorService).GetTypeInfo().Assembly;
var fileProvider = new EmbeddedFileProvider(
    viewAssembly,
    "ApplicationServices.Widgets.Html.Templates");

services.Configure<MvcRazorRuntimeCompilationOptions>(options => {
    options.FileProviders.Clear();
    options.FileProviders.Add(fileProvider);
});

services.AddRazorPages().AddRazorRuntimeCompilation();

在测试项目中我有这个设置：

var builder = new HostBuilder()
    .ConfigureWebHost(webHost =>
    {
        webHost.UseTestServer();
        webHost.UseStartup<Startup>();
    });

var host = await builder.StartAsync();

HttpClient = host.GetTestClient();

但是当我使用这个 HttpClient 调用我的端点时，IRazorViewEngine.GetView 开始抛出奇怪的异常：

Microsoft.AspNetCore.Mvc.Razor.RuntimeCompilation.CompilationFailedException: 'One or more compilation failures occurred:
rnouw0xu.21w(4,41): error CS0234: The type or namespace name 'Razor' does not exist in the namespace 'Microsoft.AspNetCore' (are you missing an assembly reference?)
rnouw0xu.21w(4,82): error CS0518: Predefined type 'System.Type' is not defined or imported
rnouw0xu.21w(4,110): error CS0518: Predefined type 'System.String' is not defined or imported
rnouw0xu.21w(4,127): error CS0518: Predefined type 'System.String' is not defined or imported
rnouw0xu.21w(8,11): error CS0246: The type or namespace name 'System' could not be found (are you missing a using directive or an assembly reference?)
rnouw0xu.21w(9,11): error CS0246: The type or namespace name 'System' could not be found (are you missing a using directive or an assembly reference?)
rnouw0xu.21w(10,11): error CS0246: The type or namespace name 'System' could not be found (are you missing a using directive or an assembly reference?)
rnouw0xu.21w(11,11): error CS0246: The type or namespace name 'System' could not be found (are you missing a using directive or an assembly reference?)
rnouw0xu.21w(13,36): error CS0234: The type or namespace name 'Rendering' does not exist in the namespace 'Microsoft.AspNetCore.Mvc' (are you missing an assembly reference?)
rnouw0xu.21w(14,36): error CS0234: The type or namespace name 'ViewFeatures' does not exist in the namespace 'Microsoft.AspNetCore.Mvc' (are you missing an assembly reference?)
rnouw0xu.21w(29,35): error CS0234: The type or namespace name 'Razor' does not exist in the namespace 'Microsoft.AspNetCore' (are you missing an assembly reference?)
rnouw0xu.21w(29,78): error CS0518: Predefined type 'System.String' is not defined or imported
rnouw0xu.21w(29,87): error CS0518: Predefined type 'System.String' is not defined or imported

我尝试以多种不同的方式修复此错误，但看起来我被困在这里了。

Answer 1

看来我在这篇文章中找到了答案： https://github.com/aspnet/Razor/issues/1212

我刚刚将此代码添加到我的 test.csproj 文件中：

<Target Name="CopyDepsFiles" AfterTargets="Build" Condition="'$(TargetFramework)'!=''">

   <ItemGroup>
    <DepsFilePaths Include="$([System.IO.Path]::ChangeExtension('%(_ResolvedProjectReferencePaths.FullPath)', '.deps.json'))" />
   </ItemGroup>

   <Copy SourceFiles="%(DepsFilePaths.FullPath)" DestinationFolder="$(OutputPath)" Condition="Exists('%(DepsFilePaths.FullPath)')" />

</Target>

Answer 2

只是稍微扩展了已批准的答案，因为在升级到 .NET 6 时建议的修复对我不起作用，运行时仍然无法找到程序集，直到我明确添加 AddApplicationPart(assembly) 调用IMvcBuilder.

还有一个小的简化是将选项 lambda 传递给 AddRazordRuntimeCompilation 调用，在这种情况下可以删除 services.Configure<MvcRazorRuntimeCompilationOptions>。

它可能由于多种原因而失败（这是一个 Windows 服务项目，视图在一个单独的 dll 中），但无论如何这是我从网上收集的各种修复程序的汇编：

// this part is needed if you don't have a valid IWebHostEnvironment
// service registered, in which case you need to create your own dummy
// implementation because Razor needs IWebHostEnvironment.ApplicationName
// (it should return Assembly.GetEntryAssembly().GetName().Name, and you 
// can leave other properties null)
services.AddSingleton<IWebHostEnvironment, DummyHostingEnvironment>();
services.AddSingleton<IHostEnvironment, DummyHostingEnvironment>();

// this also needs to be registered as two separate dependencies
// if you're getting "Unable to resolve service for type
// 'System.Diagnostics.DiagnosticListener'"
// (see https://github.com/dotnet/aspnetcore/issues/14544)
var diagnosticSource = new DiagnosticListener("Microsoft.AspNetCore");
services.AddSingleton<DiagnosticSource>(diagnosticSource);
services.AddSingleton<DiagnosticListener>(diagnosticSource);

// make sure you specify correct assemblies, in case the views
// are in a separate dll
var assemblyWithTemplates = ...;
var assemblyReferencingTheRazorPackage = ...;

services
    .AddRazorPages()
    .AddApplicationPart(assemblyReferencingTheRazorPackage ) // <-- added this
    .AddRazorRuntimeCompilation(options =>
    {
        // important to clear because some of them are null
        options.FileProviders.Clear();

        // resolve views as embedded resources
        options.FileProviders.Add(new EmbeddedFileProvider(assemblyWithTemplates));
    });

然后还将已接受答案中的代码添加到 .csproj 文件，以便正确复制 .deps 文件。

从 AspNetCore TestHost 运行时编译 Razor 期间出现 CompilationFailedException

CompilationFailedException during runtime compilation of Razor from AspNetCore TestHost

c#

razor

.net-core

asp.net-core

asp.net-core-testhost