如何解决未将对象引用设置为对象Exceptionmv的实例

Question

我正在使用Entity Framework处理MVC 5应用程序，我正在尝试在视图上显示已添加页面的列表，但我得到的对象引用未设置为对象的实例。我附上了控制器代码，源错误和堆栈跟踪。我期待着这里的任何人的解决方案。非常感谢。

var pages = _context.MenuPages.ToList();

        if (query != null)
            page = 1;

        if (!String.IsNullOrWhiteSpace(query))
        {

            //pages = pages.Where(f => f.Name.Equals(query));
        }

        var viewModel = new PageViewModel
        {
            AllSitePages = pages.OrderBy(i => i.Id).ToPagedList(page ?? 1, pageSize),
            SearchTerm = query,
            PageSize = pageSize,
            PageSizeList = new SelectList(new int[] { 5, 10, 20, 100 }),
            PageSerialNumber = _common.GetSerialNumberForPage(page ?? 1, pageSize)
        };
        return View(viewModel);

来源错误：

Line 38:             var viewModel = new PageViewModel
Line 39:             {
Line 40:                 AllSitePages = pages.OrderBy(i => i.Id).ToPagedList(page ?? 1, pageSize),

堆栈追踪：

[NullReferenceException: Object reference not set to an instance of an object.]
   UGDC.Controllers.PagesController.Index(Nullable`1 page, Int32 pageSize, String query) in c:\Users\kAkaa\documents\visual studio 2015\Projects\UGDC\UGDC\Controllers\PagesController.cs:38
   lambda_method(Closure , ControllerBase , Object[] ) +194
   System.Web.Mvc.ActionMethodDispatcher.Execute(ControllerBase controller, Object[] parameters) +14
   System.Web.Mvc.ReflectedActionDescriptor.Execute(ControllerContext controllerContext, IDictionary`2 parameters) +157
   System.Web.Mvc.ControllerActionInvoker.InvokeActionMethod(ControllerContext controllerContext, ActionDescriptor actionDescriptor, IDictionary`2 parameters) +27
   System.Web.Mvc.Async.AsyncControllerActionInvoker.<BeginInvokeSynchronousActionMethod>b__39(IAsyncResult asyncResult, ActionInvocation innerInvokeState) +22
   System.Web.Mvc.Async.WrappedAsyncResult`2.CallEndDelegate(IAsyncResult asyncResult) +29
   System.Web.Mvc.Async.WrappedAsyncResultBase`1.End() +49
   System.Web.Mvc.Async.AsyncControllerActionInvoker.EndInvokeActionMethod(IAsyncResult asyncResult) +32
   System.Web.Mvc.Async.AsyncInvocationWithFilters.<InvokeActionMethodFilterAsynchronouslyRecursive>b__3d() +50
   System.Web.Mvc.Async.<>c__DisplayClass46.<InvokeActionMethodFilterAsynchronouslyRecursive>b__3f() +228
   System.Web.Mvc.Async.<>c__DisplayClass33.<BeginInvokeActionMethodWithFilters>b__32(IAsyncResult asyncResult) +10
   System.Web.Mvc.Async.WrappedAsyncResult`1.CallEndDelegate(IAsyncResult asyncResult) +10
   System.Web.Mvc.Async.WrappedAsyncResultBase`1.End() +49
   System.Web.Mvc.Async.AsyncControllerActionInvoker.EndInvokeActionMethodWithFilters(IAsyncResult asyncResult) +34
   System.Web.Mvc.Async.<>c__DisplayClass2b.<BeginInvokeAction>b__1c() +26
   System.Web.Mvc.Async.<>c__DisplayClass21.<BeginInvokeAction>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.<BeginExecuteCore>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.<BeginExecute>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.<BeginProcessRequest>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() +9765901
   System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) +155