Question

我们正在尝试在ASP.NET MVC 5中开发企业CMS应用程序。用户需要创建新页面，更改现有页面内容或从管理应用程序中完全删除页面。另一个要求是，某些页面可以包含使用Razor语法编写的自定义小部件。

这两个要求导致我从数据库加载剃刀视图。我用Google搜索并找到了几个例子。

第一个是扩展VirtualPathProvider并在Application_Start方法中使用下面的表达式注册它。

protected void Application_Start()
{
    ...
    HostingEnvironment.RegisterVirtualPathProvider(new MyVirtualPathProvider());
}

当我尝试运行它时，它会抛出错误

[InvalidOperationException: The view at '~/Views/Home/Index.aspx' must derive from ViewPage, ViewPage, ViewUserControl, or ViewUserControl.]
    System.Web.Mvc.WebFormView.RenderView(ViewContext viewContext, TextWriter writer, Object instance) +180
    System.Web.Mvc.BuildManagerCompiledView.Render(ViewContext viewContext, TextWriter writer) +107
    System.Web.Mvc.ViewResultBase.ExecuteResult(ControllerContext context) +291
    System.Web.Mvc.ControllerActionInvoker.InvokeActionResult(ControllerContext controllerContext, ActionResult actionResult) +13
    System.Web.Mvc.ControllerActionInvoker.InvokeActionResultFilterRecursive(IList`1 filters, Int32 filterIndex, ResultExecutingContext preContext, ControllerContext controllerContext, ActionResult actionResult) +56
    System.Web.Mvc.ControllerActionInvoker.InvokeActionResultFilterRecursive(IList`1 filters, Int32 filterIndex, ResultExecutingContext preContext, ControllerContext controllerContext, ActionResult actionResult) +420
    System.Web.Mvc.ControllerActionInvoker.InvokeActionResultWithFilters(ControllerContext controllerContext, IList`1 filters, ActionResult actionResult) +52
    System.Web.Mvc.Async.c__DisplayClass2b.b__1c() +173
    System.Web.Mvc.Async.c__DisplayClass21.b__1e(IAsyncResult asyncResult) +100
    System.Web.Mvc.Async.WrappedAsyncResult`1.CallEndDelegate(IAsyncResult asyncResult) +10
    System.Web.Mvc.Async.WrappedAsyncResultBase`1.End() +49
    System.Web.Mvc.Async.AsyncControllerActionInvoker.EndInvokeAction(IAsyncResult asyncResult) +27
    System.Web.Mvc.Controller.b__1d(IAsyncResult asyncResult, ExecuteCoreState innerState) +13
    System.Web.Mvc.Async.WrappedAsyncVoid`1.CallEndDelegate(IAsyncResult asyncResult) +29
    System.Web.Mvc.Async.WrappedAsyncResultBase`1.End() +49
    System.Web.Mvc.Controller.EndExecuteCore(IAsyncResult asyncResult) +36
    System.Web.Mvc.Controller.b__15(IAsyncResult asyncResult, Controller controller) +12
    System.Web.Mvc.Async.WrappedAsyncVoid`1.CallEndDelegate(IAsyncResult asyncResult) +22
    System.Web.Mvc.Async.WrappedAsyncResultBase`1.End() +49
    System.Web.Mvc.Controller.EndExecute(IAsyncResult asyncResult) +26
    System.Web.Mvc.Controller.System.Web.Mvc.Async.IAsyncController.EndExecute(IAsyncResult asyncResult) +10
    System.Web.Mvc.MvcHandler.b__5(IAsyncResult asyncResult, ProcessRequestState innerState) +21
    System.Web.Mvc.Async.WrappedAsyncVoid`1.CallEndDelegate(IAsyncResult asyncResult) +29
    System.Web.Mvc.Async.WrappedAsyncResultBase`1.End() +49
    System.Web.Mvc.MvcHandler.EndProcessRequest(IAsyncResult asyncResult) +28
    System.Web.Mvc.MvcHandler.System.Web.IHttpAsyncHandler.EndProcessRequest(IAsyncResult result) +9
    System.Web.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() +9644097
    System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) +155

另一个例子是

protected void Application_Start()
{
    ...
    ViewEngines.Engines.Clear();
    ViewEngines.Engines.Add(new MyViewEngine());
}

private class MyViewEngine : RazorViewEngine
{
    public MyViewEngine()
    {
        this.VirtualPathProvider = new MyVirtualPathProvider();
    }
}

当指定的文件（例如/View/Home/Index.cshtml）在文件系统中时，即使它没有任何内容，也可以使用此文件。当我从文件系统中删除文件时，抛出以下错误

[InvalidOperationException: The view 'Index' or its master was not found or no view engine supports the searched locations. The following locations were searched:
    ~/Views/Home/Index.cshtml
    ~/Views/Home/Index.vbhtml
    ~/Views/Shared/Index.cshtml
    ~/Views/Shared/Index.vbhtml]
    System.Web.Mvc.ViewResult.FindView(ControllerContext context) +382
    System.Web.Mvc.ViewResultBase.ExecuteResult(ControllerContext context) +116
    System.Web.Mvc.ControllerActionInvoker.InvokeActionResult(ControllerContext controllerContext, ActionResult actionResult) +13
    System.Web.Mvc.ControllerActionInvoker.InvokeActionResultFilterRecursive(IList`1 filters, Int32 filterIndex, ResultExecutingContext preContext, ControllerContext controllerContext, ActionResult actionResult) +56
    System.Web.Mvc.ControllerActionInvoker.InvokeActionResultFilterRecursive(IList`1 filters, Int32 filterIndex, ResultExecutingContext preContext, ControllerContext controllerContext, ActionResult actionResult) +420
    System.Web.Mvc.ControllerActionInvoker.InvokeActionResultWithFilters(ControllerContext controllerContext, IList`1 filters, ActionResult actionResult) +52
    System.Web.Mvc.Async.c__DisplayClass2b.b__1c() +173
    System.Web.Mvc.Async.c__DisplayClass21.b__1e(IAsyncResult asyncResult) +100
    System.Web.Mvc.Async.WrappedAsyncResult`1.CallEndDelegate(IAsyncResult asyncResult) +10
    System.Web.Mvc.Async.WrappedAsyncResultBase`1.End() +49
    System.Web.Mvc.Async.AsyncControllerActionInvoker.EndInvokeAction(IAsyncResult asyncResult) +27
    System.Web.Mvc.Controller.b__1d(IAsyncResult asyncResult, ExecuteCoreState innerState) +13
    System.Web.Mvc.Async.WrappedAsyncVoid`1.CallEndDelegate(IAsyncResult asyncResult) +29
    System.Web.Mvc.Async.WrappedAsyncResultBase`1.End() +49
    System.Web.Mvc.Controller.EndExecuteCore(IAsyncResult asyncResult) +36
    System.Web.Mvc.Controller.b__15(IAsyncResult asyncResult, Controller controller) +12
    System.Web.Mvc.Async.WrappedAsyncVoid`1.CallEndDelegate(IAsyncResult asyncResult) +22
    System.Web.Mvc.Async.WrappedAsyncResultBase`1.End() +49
    System.Web.Mvc.Controller.EndExecute(IAsyncResult asyncResult) +26
    System.Web.Mvc.Controller.System.Web.Mvc.Async.IAsyncController.EndExecute(IAsyncResult asyncResult) +10
    System.Web.Mvc.MvcHandler.b__5(IAsyncResult asyncResult, ProcessRequestState innerState) +21
    System.Web.Mvc.Async.WrappedAsyncVoid`1.CallEndDelegate(IAsyncResult asyncResult) +29
    System.Web.Mvc.Async.WrappedAsyncResultBase`1.End() +49
    System.Web.Mvc.MvcHandler.EndProcessRequest(IAsyncResult asyncResult) +28
    System.Web.Mvc.MvcHandler.System.Web.IHttpAsyncHandler.EndProcessRequest(IAsyncResult result) +9
    System.Web.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() +9644097
    System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) +155

即使您覆盖VirtualPathProvider以从数据库加载视图数据，RazorViewEngine也会尝试在文件系统中查找该文件。

我想这些示例适用于以前版本的ASP.NET MVC（我认为2或3）。我得到的最好的解决方案是从头开始编写自定义视图引擎，但是要做的工作太多，以使其像剃刀视图引擎一样工作。是否还有其他技巧可以使这些示例有效或者其他替代方案？

Answer 1

查看这些链接。希望这可能有所帮助。

http://rebuildall.umbraworks.net/2009/11/17/ASP_NET_MVC_and_virtual_views

Using custom VirtualPathProvider to load embedded resource Partial Views

Storing ASP.Net MVC Views in the Database

ASP.NET MVC load Razor view from database

从ASP.NET MVC 5中的数据库加载Razor视图

1 个答案: