LINQ to Entities returning "Object reference not set to an instance of an object."

Question

I have a piece of code that checks to see if a user is in our database using a view called RESOURCE_V. If not, the code uses Entity Framework to add the user to the database using the user's information from Active Directory. I would then like to re-query the RESOURCE_V view to get the submitted information. Upon doing so I am getting "Object reference not set to an instance of an object.". Here is the full code:

HALEntities context = new HALEntities();
            List<RESOURCE_V> userData = (from i in context.RESOURCE_V
                                         where i.NT_USER_N == Environment.UserName
                                         select i).ToList();

            // add user to RSRC table using Active Directory details
            if (userData.Count > 0)
            {
                PrincipalContext principleContext = new PrincipalContext(ContextType.Domain, HAL_Globals.domain);
                UserPrincipal user = UserPrincipal.FindByIdentity(principleContext, IdentityType.SamAccountName, HAL_Globals.domain + "\\" + Environment.UserName);
                RSRC rsrc = new RSRC();

                rsrc.RSRC_I = context.RSRCs.Select(u => u.RSRC_I).Max() + 1;
                rsrc.NT_USER_N = user.SamAccountName + "AAAA";
                rsrc.FRST_N = user.GivenName;
                rsrc.LAST_N = user.Surname;
                rsrc.INIL_N = (user.MiddleName == null) ? "X" : user.MiddleName.Substring(0, 1);
                rsrc.SHRT_N = user.GivenName.Substring(0, 1) + ((user.MiddleName == null) ? "X" : user.MiddleName.Substring(0, 1)) + user.Surname.Substring(0, 1);
                rsrc.EMAIL_I = user.EmailAddress;
                rsrc.TELE_I = user.VoiceTelephoneNumber.Replace("(", "").Replace(")", "").Replace("-", "");
                rsrc.ACTV_F = true;
                rsrc.CRTE_USER_I = Environment.UserName;
                rsrc.CRTE_TS = DateTime.Now;
                rsrc.UPDT_USER_I = Environment.UserName;
                rsrc.UPDT_TS = DateTime.Now;

                context.RSRCs.Add(rsrc);
                context.SaveChanges();
                userData = (from i in context.RESOURCE_V
                            where i.NT_USER_N == Environment.UserName + "AAAA"
                            select i).ToList();
            }

Notice the logic doesn't exactly match my description as I am using this code to test against my ID that already exists. The line that errors out is the very last statement in the if block:

userData = (from i in context.RESOURCE_V
                            where i.NT_USER_N == Environment.UserName + "AAAA"
                            select i).ToList();

I have tried recreating the Entity context, using different LINQ syntax, but have had no luck. Any help would be appreciated.

Edit:

As requested, here is the stack trace:

   at System.RuntimeTypeHandle.CreateInstance(RuntimeType type, Boolean publicOnly, Boolean noCheck, Boolean& canBeCached, RuntimeMethodHandleInternal& ctor, Boolean& bNeedSecurityCheck)
   at System.RuntimeType.CreateInstanceSlow(Boolean publicOnly, Boolean skipCheckThis, Boolean fillCache, StackCrawlMark& stackMark)
   at System.RuntimeType.CreateInstanceDefaultCtor(Boolean publicOnly, Boolean skipCheckThis, Boolean fillCache, StackCrawlMark& stackMark)
   at System.Activator.CreateInstance(Type type, Boolean nonPublic)
   at System.RuntimeType.CreateInstanceImpl(BindingFlags bindingAttr, Binder binder, Object[] args, CultureInfo culture, Object[] activationAttributes, StackCrawlMark& stackMark)
   at System.Activator.CreateInstance(Type type, BindingFlags bindingAttr, Binder binder, Object[] args, CultureInfo culture, Object[] activationAttributes)
   at System.Activator.CreateInstance(Type type, Object[] args)
   at System.Xaml.Schema.SafeReflectionInvoker.CreateInstanceCritical(Type type, Object[] arguments)
   at System.Xaml.Schema.SafeReflectionInvoker.CreateInstance(Type type, Object[] arguments)
   at System.Xaml.Schema.XamlTypeInvoker.CreateInstance(Object[] arguments)
   at MS.Internal.Xaml.Runtime.ClrObjectRuntime.CreateInstanceWithCtor(XamlType xamlType, Object[] args)
   at MS.Internal.Xaml.Runtime.ClrObjectRuntime.CreateInstance(XamlType xamlType, Object[] args)
   at MS.Internal.Xaml.Runtime.PartialTrustTolerantRuntime.CreateInstance(XamlType xamlType, Object[] args)
   at System.Xaml.XamlObjectWriter.Logic_CreateAndAssignToParentStart(ObjectWriterContext ctx)
   at System.Xaml.XamlObjectWriter.WriteStartMember(XamlMember property)
   at System.Xaml.XamlWriter.WriteNode(XamlReader reader)
   at System.Windows.Markup.WpfXamlLoader.TransformNodes(XamlReader xamlReader, XamlObjectWriter xamlWriter, Boolean onlyLoadOneNode, Boolean skipJournaledProperties, Boolean shouldPassLineNumberInfo, IXamlLineInfo xamlLineInfo, IXamlLineInfoConsumer xamlLineInfoConsumer, XamlContextStack`1 stack, IStyleConnector styleConnector)
   at System.Windows.Markup.WpfXamlLoader.Load(XamlReader xamlReader, IXamlObjectWriterFactory writerFactory, Boolean skipJournaledProperties, Object rootObject, XamlObjectWriterSettings settings, Uri baseUri)
   at System.Windows.Markup.WpfXamlLoader.LoadBaml(XamlReader xamlReader, Boolean skipJournaledProperties, Object rootObject, XamlAccessLevel accessLevel, Uri baseUri)
   at System.Windows.Markup.XamlReader.LoadBaml(Stream stream, ParserContext parserContext, Object parent, Boolean closeStream)
   at System.Windows.Application.LoadBamlStreamWithSyncInfo(Stream stream, ParserContext pc)
   at System.Windows.Application.LoadComponent(Uri resourceLocator, Boolean bSkipJournaledProperties)
   at System.Windows.Application.DoStartup()
   at System.Windows.Application.<.ctor>b__1(Object unused)
   at System.Windows.Threading.ExceptionWrapper.InternalRealCall(Delegate callback, Object args, Int32 numArgs)
   at MS.Internal.Threading.ExceptionFilterHelper.TryCatchWhen(Object source, Delegate method, Object args, Int32 numArgs, Delegate catchHandler)
   at System.Windows.Threading.DispatcherOperation.InvokeImpl()
   at System.Windows.Threading.DispatcherOperation.InvokeInSecurityContext(Object state)
   at System.Threading.ExecutionContext.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)
   at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)
   at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)
   at System.Windows.Threading.DispatcherOperation.Invoke()
   at System.Windows.Threading.Dispatcher.ProcessQueue()
   at System.Windows.Threading.Dispatcher.WndProcHook(IntPtr hwnd, Int32 msg, IntPtr wParam, IntPtr lParam, Boolean& handled)
   at MS.Win32.HwndWrapper.WndProc(IntPtr hwnd, Int32 msg, IntPtr wParam, IntPtr lParam, Boolean& handled)
   at MS.Win32.HwndSubclass.DispatcherCallbackOperation(Object o)
   at System.Windows.Threading.ExceptionWrapper.InternalRealCall(Delegate callback, Object args, Int32 numArgs)
   at MS.Internal.Threading.ExceptionFilterHelper.TryCatchWhen(Object source, Delegate method, Object args, Int32 numArgs, Delegate catchHandler)
   at System.Windows.Threading.Dispatcher.LegacyInvokeImpl(DispatcherPriority priority, TimeSpan timeout, Delegate method, Object args, Int32 numArgs)
   at MS.Win32.HwndSubclass.SubclassWndProc(IntPtr hwnd, Int32 msg, IntPtr wParam, IntPtr lParam)
   at MS.Win32.UnsafeNativeMethods.DispatchMessage(MSG& msg)
   at System.Windows.Threading.Dispatcher.PushFrameImpl(DispatcherFrame frame)
   at System.Windows.Threading.Dispatcher.PushFrame(DispatcherFrame frame)
   at System.Windows.Threading.Dispatcher.Run()
   at System.Windows.Application.RunDispatcher(Object ignore)
   at System.Windows.Application.RunInternal(Window window)
   at System.Windows.Application.Run(Window window)
   at System.Windows.Application.Run()
   at HAL.App.Main() in c:\HAL\HAL_PROD\HAL\obj\Debug\App.g.cs:line 0
   at System.AppDomain._nExecuteAssembly(RuntimeAssembly assembly, String[] args)
   at System.AppDomain.nExecuteAssembly(RuntimeAssembly assembly, String[] args)
   at System.Runtime.Hosting.ManifestRunner.Run(Boolean checkAptModel)
   at System.Runtime.Hosting.ManifestRunner.ExecuteAsAssembly()
   at System.Runtime.Hosting.ApplicationActivator.CreateInstance(ActivationContext activationContext, String[] activationCustomData)
   at System.Runtime.Hosting.ApplicationActivator.CreateInstance(ActivationContext activationContext)
   at System.Activator.CreateInstance(ActivationContext activationContext)
   at Microsoft.VisualStudio.HostingProcess.HostProc.RunUsersAssemblyDebugInZone()
   at System.Threading.ThreadHelper.ThreadStart_Context(Object state)
   at System.Threading.ExecutionContext.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)
   at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)
   at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)
   at System.Threading.ThreadHelper.ThreadStart()

Edit 2: The Inner Exception Stack Trace:

at System.Data.EntityKey.AddHashValue(Int32 hashCode, Object keyValue)
   at System.Data.EntityKey.GetHashCode()
   at System.Collections.Generic.GenericEqualityComparer`1.GetHashCode(T obj)
   at System.Collections.Generic.Dictionary`2.FindEntry(TKey key)
   at System.Collections.Generic.Dictionary`2.TryGetValue(TKey key, TValue& value)
   at System.Data.Objects.ObjectStateManager.TryGetEntityEntry(EntityKey key, EntityEntry& entry)
   at System.Data.Common.Internal.Materialization.Shaper.HandleEntityAppendOnly[TEntity](Func`2 constructEntityDelegate, EntityKey entityKey, EntitySet entitySet)
   at lambda_method(Closure , Shaper )
   at System.Data.Common.Internal.Materialization.Coordinator`1.ReadNextElement(Shaper shaper)
   at System.Data.Common.Internal.Materialization.Shaper`1.SimpleEnumerator.MoveNext()
   at System.Collections.Generic.List`1..ctor(IEnumerable`1 collection)
   at System.Linq.Enumerable.ToList[TSource](IEnumerable`1 source)
   at HAL.HAL_CurrentUser..ctor(SqlConnection currentServerConnection) in c:\HAL\HAL_PROD\HAL\Global Classes\HAL_CurrentUser.cs:line 86
   at HAL.HAL_CurrentUser.get_Instance() in c:\HAL\HAL_PROD\HAL\Global Classes\HAL_CurrentUser.cs:line 46
   at HAL.WelcomeViewModel..ctor() in c:\HAL\HAL_PROD\HAL\HAL Classes\Welcome\WelcomeViewModel.cs:line 21
   at HAL.Welcome..ctor() in c:\HAL\HAL_PROD\HAL\HAL Classes\Welcome\Welcome.xaml.cs:line 26
   at HAL.Navigation..ctor() in c:\HAL\HAL_PROD\HAL\Navigation.xaml.cs:line 17

Edit 3:

After playing around with the values being queried in the second LINQ query I have determined the issue is being caused by the fact that I am filtering on the new ID in the where clause of the LINQ query. If I hard-code another ID in the query it works and the error is not thrown. I have determined the new ID is in fact being added to the database.

Answer 1

The entity has a composite key and when you save the new entity one of the key column is null. EF does not support nullable keys (it throws) but apparently there is a bug in EF where this condition is not checked in this specific scenario and hence the NRE. You need to make sure that you are not returning null values in primary key columns.

Answer 2

I had the same problem. My class field of collection type was empty. I struggled a lot to fix the problem. Finally the error was in typo - I was creating the object with new while making local declaration for the class field name and then it was going out of local scope. I know that it doesn't answer the topic, but as a point to re-check the code for such errors. Sorry, I really wanted to help other guys like me with the similar problem.