Question

我正在尝试为我的网站创建一个错误横幅，例如webjob失败，第三方服务失败等等。我在我的控制器中放了一个函数来查询我的“错误”表，理想情况下应该显示每条消息风景。我在布局页面中进行了部分页面渲染，但是由于部分页面在创建和渲染实际网站内容之前呈现，因此我遇到了NullReferenceException错误。这是堆栈跟踪：

在实例化之前，我对如何访问数据库感到有点迷茫。如何在页面的其余部分加载之前访问数据并显示它？还有更好的方法来实现这个错误横幅吗？

编辑：上下文的一些代码。

这是布局文件结构：

[NullReferenceException: Object reference not set to an instance of an object.]
System.Web.HttpContextBaseExtensions.GetOwinEnvironment(HttpContextBase context) +34
System.Web.HttpContextBaseExtensions.GetOwinContext(HttpContextBase context) +50
Webapp.Controllers.ManageController.getContext() in c:\Users\Sergey\Source\Workspaces\xxx\xxx\Webapp\Controllers\ManageController.cs:26
Webapp.Controllers.ManageController.SiteErrorBanner() in c:\Users\Sergey\Source\Workspaces\xxx\xxx\Webapp\Controllers\ManageController.cs:485
ASP._Page_Views_Shared__Layout_cshtml.Execute() in c:\Users\Sergey\Source\Workspaces\xxx\xxx\Webapp\Views\Shared\_Layout.cshtml:25
System.Web.WebPages.WebPageBase.ExecutePageHierarchy() +271
System.Web.Mvc.WebViewPage.ExecutePageHierarchy() +121
System.Web.WebPages.WebPageBase.ExecutePageHierarchy(WebPageContext pageContext, TextWriter writer, WebPageRenderingBase startPage) +145
System.Web.WebPages.WebPageBase.ExecutePageHierarchy(WebPageContext pageContext, TextWriter writer) +41
System.Web.WebPages.<>c__DisplayClass3.<RenderPageCore>b__2(TextWriter writer) +335
System.Web.WebPages.HelperResult.WriteTo(TextWriter writer) +42
System.Web.WebPages.WebPageExecutingBase.WriteTo(TextWriter writer, HelperResult content) +45
System.Web.WebPages.WebPageBase.Write(HelperResult result) +53
System.Web.WebPages.WebPageBase.RenderSurrounding(String partialViewName, Action`1 body) +178
System.Web.WebPages.WebPageBase.PopContext() +229
System.Web.WebPages.WebPageBase.ExecutePageHierarchy(WebPageContext pageContext, TextWriter writer, WebPageRenderingBase startPage) +154
System.Web.Mvc.RazorView.RenderView(ViewContext viewContext, TextWriter writer, Object instance) +695
System.Web.Mvc.BuildManagerCompiledView.Render(ViewContext viewContext, TextWriter writer) +382
System.Web.Mvc.ViewResultBase.ExecuteResult(ControllerContext context) +431
System.Web.Mvc.ControllerActionInvoker.InvokeActionResult(ControllerContext controllerContext, ActionResult actionResult) +39
System.Web.Mvc.ControllerActionInvoker.InvokeActionResultFilterRecursive(IList`1 filters, Int32 filterIndex, ResultExecutingContext preContext, ControllerContext controllerContext, ActionResult actionResult) +116
System.Web.Mvc.ControllerActionInvoker.InvokeActionResultFilterRecursive(IList`1 filters, Int32 filterIndex, ResultExecutingContext preContext, ControllerContext controllerContext, ActionResult actionResult) +529
System.Web.Mvc.ControllerActionInvoker.InvokeActionResultWithFilters(ControllerContext controllerContext, IList`1 filters, ActionResult actionResult) +106
System.Web.Mvc.Async.<>c__DisplayClass2b.<BeginInvokeAction>b__1c() +321
System.Web.Mvc.Async.<>c__DisplayClass21.<BeginInvokeAction>b__1e(IAsyncResult asyncResult) +185
System.Web.Mvc.Async.WrappedAsyncResult`1.CallEndDelegate(IAsyncResult asyncResult) +42
System.Web.Mvc.Async.WrappedAsyncResultBase`1.End() +133
System.Web.Mvc.Async.AsyncResultWrapper.End(IAsyncResult asyncResult, Object tag) +56
System.Web.Mvc.Async.AsyncControllerActionInvoker.EndInvokeAction(IAsyncResult asyncResult) +40
System.Web.Mvc.Controller.<BeginExecuteCore>b__1d(IAsyncResult asyncResult, ExecuteCoreState innerState) +34
System.Web.Mvc.Async.WrappedAsyncVoid`1.CallEndDelegate(IAsyncResult asyncResult) +70
System.Web.Mvc.Async.WrappedAsyncResultBase`1.End() +139
System.Web.Mvc.Async.AsyncResultWrapper.End(IAsyncResult asyncResult, Object tag) +59
System.Web.Mvc.Async.AsyncResultWrapper.End(IAsyncResult asyncResult, Object tag) +40
System.Web.Mvc.Controller.EndExecuteCore(IAsyncResult asyncResult) +44
System.Web.Mvc.Controller.<BeginExecute>b__15(IAsyncResult asyncResult, Controller controller) +39
System.Web.Mvc.Async.WrappedAsyncVoid`1.CallEndDelegate(IAsyncResult asyncResult) +62
System.Web.Mvc.Async.WrappedAsyncResultBase`1.End() +139
System.Web.Mvc.Async.AsyncResultWrapper.End(IAsyncResult asyncResult, Object tag) +59
System.Web.Mvc.Async.AsyncResultWrapper.End(IAsyncResult asyncResult, Object tag) +40
System.Web.Mvc.Controller.EndExecute(IAsyncResult asyncResult) +39
System.Web.Mvc.Controller.System.Web.Mvc.Async.IAsyncController.EndExecute(IAsyncResult asyncResult) +39
System.Web.Mvc.MvcHandler.<BeginProcessRequest>b__5(IAsyncResult asyncResult, ProcessRequestState innerState) +39
System.Web.Mvc.Async.WrappedAsyncVoid`1.CallEndDelegate(IAsyncResult asyncResult) +70
System.Web.Mvc.Async.WrappedAsyncResultBase`1.End() +139
System.Web.Mvc.Async.AsyncResultWrapper.End(IAsyncResult asyncResult, Object tag) +59
System.Web.Mvc.Async.AsyncResultWrapper.End(IAsyncResult asyncResult, Object tag) +40
System.Web.Mvc.MvcHandler.EndProcessRequest(IAsyncResult asyncResult) +40
System.Web.Mvc.MvcHandler.System.Web.IHttpAsyncHandler.EndProcessRequest(IAsyncResult result) +38
System.Web.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() +9651516
System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) +155

以下是控制器中的相关功能：

<html>
<head>
    <!-- meta tags, etc. -->
    @Styles.Render("~/Content/css")
    @Scripts.Render("~/bundles/modernizr")
    @Scripts.Render("~/bundles/jquery")
    @Scripts.Render("~/bundles/jqueryval")
    @Scripts.Render("~/bundles/bootstrap")
</head>
<body>
<div id="wrapper">
    @Html.Action(MVC.Manage.SiteErrorBanner())
    <!-- nav, other user profile dropdowns, etc -->
    @RenderBody()
</body>
</html>

在为其设置实例之前引用DbContext

0 个答案: