From your code, it looks like provider is a variant or some other variable, and not an object. Is Nothing is for objects only, yet later you say it’s a value that should either be NULL or NOT NULL, which would be handled by IsNull. Try using: If Not IsNull(provider) Then url = url & … Read more
According to the documentation (Explicit conversions) you can cast from a base type to a derived type. Since null is a valid value for all reference types, as long as the cast route exists you should be fine. object null → TestClass null works as object is a superclass to all reference types. However, if … Read more
I’ll lay out my hypothesis here. The stack is leading you to believe that this is where the crash occurs, but it occurs elsewhere. We’re looking at the wrong thread. I don’t know if this would be practical, but sometimes good old “printf debugging” helps. What if you print out the value you’re looking for … Read more
From your code, it looks like provider is a variant or some other variable, and not an object. Is Nothing is for objects only, yet later you say it’s a value that should either be NULL or NOT NULL, which would be handled by IsNull. Try using: If Not IsNull(provider) Then url = url & … Read more
in C# you can overload operators to add custom logic on some comparison like this. For example: class Test { public string SomeProp { get; set; } public static bool operator ==(Test test1, Test test2) { return test1.SomeProp == test2.SomeProp; } public static bool operator !=(Test test1, Test test2) { return !(test1 == test2); } … Read more
Use this if the session variable emp_num will store a string: if (!string.IsNullOrEmpty(Session[“emp_num”] as string)) { //The code } If it doesn’t store a string, but some other type, you should just check for null before accessing the value, as in your second example.
You should have your entity create those lists in the constructor. EF doesn’t create dependent collections, and expects the entity to do so. So, your case, you would make your entity like this: class MyClass{ public List<OtherClass> _otherClasses {get;set;} public MyClass() { _otherClasses = new List<OtherClass>(); } }
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 = Path.Combine(HttpRuntime.AppDomainAppPath, “email/teste.html”);
You can add ?? Operator so if ?. returns null task use CompletedTask instead. await (this.MyObject?.MyMethod() ?? Task.CompletedTask) I would’ve expected that the call to “MyMethod” would simply not be made if “MyObject” is null. Thats true. the ?. operator returns null task instead of calling MyMethod. the null reference exception is made because you … Read more