Referencing a DbContext before setting an instance to it - asp.net

Question

I'm trying to create an error banner for my site for things like a webjob failing, third party service down, etc. I put a function in my controller that queries my "errors" table and should ideally display each message in the view. I made the partial page render in my layout page, however I run into a NullReferenceException error since the partial page renders before the actual site's content is created and rendered. Here is the stack trace:
[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
I'm a bit lost as to how to access the database before it's instantiated. How does one access the data and display it before the rest of the page loads? Is there a better way to implement this error banner too?
Edit: some code for context.
Here's the layout file structure:
<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>
Here are the relevant functions in the controller:
public partial class ManageController : Controller
{
private ApplicationSignInManager _signInManager;
private ApplicationUserManager _userManager;
private DBContext _dbContext;
public DBContext DBContext
{
get
{
return _dbContext ?? HttpContext.GetOwinContext().Get<DBContext>();
}
private set
{
_dbContext = value;
}
}
// some user profile functions
[ChildActionOnly]
public ActionResult SiteErrorBanner()
{
var model = new Webapp.Models.SiteErrorModel();
model.UnresolvedErrors = new List<DataLibrary.site_errors>();
model.UnresolvedErrors = DBContext.site_errors.Where(error => error.resolved == false).ToList();
return PartialView(MVC.Shared.Views.ErrorBanner, model);
}
}