Null value

albert albert

12y2.6kLearn iOS Programming

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

2 Replies

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Vulpes12y ago
Accepted 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);

0
albert albert12y ago
Thank you for your answare!!

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