nullreferenceexception

How did I get this NullReferenceException error here right after the constructor?

由 ╄→гoц情女王★ 提交于 2019-11-27 07:23:09
I've had an asp.net website running live on our intranet for a couple of weeks now. I just got an email from my application_error emailer method with an unhandled exception. Here it is (I've cleaned up some of the paths to make it better displayed) Exception : Object reference not set to an instance of an object. Stack Trace : at System.Collections.Generic.Dictionary`2.Insert(TKey key, TValue value, Boolean add) at System.Collections.Generic.Dictionary`2.Add(TKey key, TValue value) at TimesheetDomain.DataMappers.StaffMemberData.ReadStaff(SqlDataReader reader) in TimesheetDomain\DataMappers

ReSharper: how to remove “Possible 'System.NullReferenceException'” warning

由 独自空忆成欢 提交于 2019-11-27 06:43:23
问题 Here is a piece of code: IUser user = managerUser.GetUserById(UserId); if ( user==null ) throw new Exception(...); Quote quote = new Quote(user.FullName, user.Email); Everything is fine here. But if I replace "if" line with the following one: ComponentException<MyUserManagerException>.FailIfTrue(user == null, "Can't find user with Id=" + UserId); where function implementation is following: public abstract class ComponentException<T> : ComponentException where T : ComponentException, new() {

Checking if an object is null in C#

由 孤人 提交于 2019-11-27 06:03:19
I would like to prevent further processing on an object if it is null. In the following code I check if the object is null by either: if (!data.Equals(null)) and if (data != null) However, I receive a NullReferenceException at dataList.Add(data) . If the object was null, it should never have even entered the if -statement! Thus, I'm asking if this is proper way of checking if an object is null: public List<Object> dataList; public bool AddData(ref Object data) bool success = false; try { // I've also used "if (data != null)" which hasn't worked either if (!data.Equals(null)) { /

avoiding null reference exceptions

由 痴心易碎 提交于 2019-11-27 03:51:12
Apparently the vast majority of errors in code are null reference exceptions. Are there any general techniques to avoid encountering null reference errors? Unless I am mistaken, I am aware that in languages such as F# is it not possible to have a null value. But thats not the question, I'm asking how to avoid null reference errors in languages such as C#. David Allen When a null reference exception is displayed to the user, this indicates a defect in the code resulting from an error on the part of the developer. Here are some ideas on how to prevent these errors. My top recommendation for

How do I enforce null checking? [duplicate]

由 你离开我真会死。 提交于 2019-11-27 02:41:07
问题 This question already has answers here : avoiding null reference exceptions (15 answers) Closed 20 days ago . I'm working on a large project where, even with 10s of 1000s of automated tests and 100% code coverage, we're getting a ridiculous number of errors. About 95% of errors we get are NullReferenceExceptions. Is there any way to enforce null-checking at compile time? Barring that, is there any way to automagically enforce null-checking in unit tests without having to write the tests for

How Can a Stack Trace Point to the Wrong Line (the “return” Statement) - 40 Lines Off

由 蹲街弑〆低调 提交于 2019-11-27 01:34:15
问题 I have twice now seen a NullReferenceException logged from a Production ASP.NET MVC 4 web application - and logged on the wrong line. Not wrong by a line or two (like you would get with a PDB mismatch), but wrong by the length of the entire controller action. Example: public ActionResult Index() { var someObject = GetObjectFromService(); if (someObject.SomeProperty == "X") { // NullReferenceException here if someObject == null // do something } // about 40 more lines of code return View(); //

Why is casting a dynamic of type object to object throwing a null reference exception?

由 雨燕双飞 提交于 2019-11-27 00:05:38
问题 I have the following function: public static T TryGetArrayValue<T>(object[] array_, int index_) { ... //some checking goes up here not relevant to question dynamic boxed = array_[index_]; return (T)boxed; } When I call it in the following way, object a = new object(); object v = TUtils.TryGetArrayValue<object>(new object[] { a }, 0); (T)boxed throws a null reference exception. Any other type I put in there other than "object", it works perfectly fine. Any ideas what this is, and why it's

httpcontext.current.server.mappath Object reference not set to an instance of an object

由 只愿长相守 提交于 2019-11-26 22:49:38
问题 I am using the following code within a class: string filePath = HttpContext.Current.Server.MapPath("~/email/teste.html"); The file teste.html is in the folder But when it will open the file the following error is being generated: Object reference not set to an instance of an object. 回答1: Don't use Server.MapPath. It's slow. Use this instead, HttpRuntime.AppDomainAppPath . As long as your web site is running, this property is always available to you. Then use it like this: string filePath =

LINQ InsertOnSubmit: NullReferenceException

由 我是研究僧i 提交于 2019-11-26 21:47:03
问题 I have this code: using DC = MV6DataContext; using MV6; // Business Logic Layer // ... public DC.MV6DataContext dc = new DC.MV6DataContext(ConnectionString); IP ip = new IP(Request.UserHostAddress); dc.IPs.InsertOnSubmit(ip); dc.SubmitChanges(); // in Business Logic layer: public class IP : DC.IP { public IP(string address) { ... } } Upon attempting to InsertOnSubmit(ip), I get a NullReferenceException (Object reference not set to an instance of an object). dc is not null; ip and all

Error checking for NULL in VBScript

由 若如初见. 提交于 2019-11-26 20:49:12
问题 I have the following VBScript in a Classic ASP page: function getMagicLink(fromWhere, provider) dim url url = "magic.asp?fromwhere=" & fromWhere If Not provider is Nothing Then ' Error occurs here url = url & "&provider=" & provider End if getMagicLink = "<a target='_blank' href='" & url & "'>" & number & "</a>" end function I keep getting an "Object Required" error messager on the line that says If Not provider Is Nothing Then . Either the value is NULL, or it's not NULL, so why am I getting
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