Null value

Question

Hi everybody I have this: [code] if (medicijn.Volgorde == 999) { int medicijnHigest = medicijnService.GetAll().Where(i => i.Volgorde != 999).Max(m => m.Volgorde); medicijn.Volgorde = medicijnHigest + 1; medicijnService.Save(medicijn); } [/code] but I get this error on medicijnHigest: An exception of type 'System.InvalidOperationException' occurred in EntityFramework.dll but was not handled in user code Additional information: The cast to value type 'System.Int32' failed because the materialized value is null. Either the result type's generic parameter or the query must use a nullable type. Thank you

Vulpes · Answer

Well it sounds from the error message as if the Volgorde property of whatever object you're using here is defined as an int but should be a nullable int (int?) because there are some records in the database which don't have a value for the corresponding column. So I'd try changing Volgorde to int? and then you should be able to do something like this: int? medicijnHigest = medicijnService.GetAll().Where(i => i.Volgorde != 999).Max(m => m.Volgorde); if (medicijnHigest == null) medicijnHigest = 0; // or -1 say medicijn.Volgorde = (int) medicijnHigest + 1; medicijnService.Save(medicijn);

albert albert · Answer

Thank you for your answare!!