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 people who care about software quality, and are also using the.net programming platform, is … Read more
It’s not data that is null, but dataList. You need to create one with public List<Object> dataList = new List<Object>(); Even better: since it’s a field, make it private. And if there’s nothing preventing you, make it also readonly. Just good practice. Aside The correct way to check for nullity is if(data != null). This … Read more
In C# 6 you can use the Null Conditional Operator. So the original test will be: int? value = objectA?.PropertyA?.PropertyB?.PropertyC;
Somewhere inside the DbContext is a value that is IEnumerable and is queried with Any() (or Where() or Select() or any other LINQ-method), but this value is null. Find out if you put a query together (somewhere outside your example code) where you are using a LINQ-method, or that you used an IEnumerable as a … Read more
Variables in .NET are either reference types or value types. Value types are primitives such as integers and booleans or structures (and can be identified because they inherit from System.ValueType). Boolean variables, when declared, have a default value: bool mybool; //mybool == false Reference types, when declared, do not have a default value: class ExampleClass … Read more
What is the cause? Bottom Line You are trying to use something that is null (or Nothing in VB.NET). This means you either set it to null, or you never set it to anything at all. Like anything else, null gets passed around. If it is null in method “A”, it could be that method … Read more