ASP.NET Core 2.1 中 ViewResultExecutor 的变化

异常："No service for type 'Microsoft.AspNetCore.Mvc.ViewFeatures.ViewResultExecutor' has been registered"

之前在 ASP.NET Core 2.0 中可以正常运行的代码：

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var services = HttpContext.RequestServices; var executor = services.GetRequiredService<ViewResultExecutor>(); var viewEngine = services.GetRequiredService<IRazorViewEngine>(); var view = viewEngine.GetView(null, "~/Pages/IeAlert.cshtml", true)?.View; if (view != null) {     using (view as IDisposable)     {         await executor.ExecuteAsync(ControllerContext, view, ViewData, TempData, "text/html; charset=utf-8", 200);     }     return new EmptyResult(); }

升级到 ASP.NET Core 2.1 之后出现下面的错误：

查看 ViewResultExecutor 的定义发现 ViewResultExecutor 实现了  IActionResultExecutor<ViewResult> 接口，查看最新的 ASP.NET Core MVC 的源代码发现这样的注册：

原来 ViewResultExecutor 也被抽象了，于是改为下面的代码解决了问题：

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var services = HttpContext.RequestServices; var executor = services.GetRequiredService<IActionResultExecutor<ViewResult>>() as ViewResultExecutor     ?? throw new ArgumentNullException("executor"); var viewEngine = services.GetRequiredService<IRazorViewEngine>(); var view = viewEngine.GetView(null, "~/Pages/IeAlert.cshtml", true)?.View; if (view != null) {     using (view as IDisposable)     {         await executor.ExecuteAsync(ControllerContext, view, ViewData, TempData, "text/html; charset=utf-8", 200);     }     return new EmptyResult(); }