Handling Null Exception in Linq to Sql on a binary data type column

Question

I'm trying to get my image from my local database in wp8. Some cells in the image column contain the actual image(in a binary format) whereas others are NULL. Here is the code:

             var image_professor = (from n in College.professor
                                  where n.Surname == Getsurname(MyLongListSelector2.SelectedItem.ToString()) && n.FirstName == GetFirstname(MyLongListSelector2.SelectedItem.ToString())
                                  select n.Pic).Single();

Everything works fine if I click on a professor which images is stored in the database,but if a professor without an image is selected then I get a NullException. Is there a way that I could use a if-else check inside my Linq query and somehow get another value if the query run's on Null or should I use another approach.

Giannis Paraskevopoulos · Accepted Answer · 2014-07-20 15:46:33Z

1

         var image_professor = (from n in College.professor
                              where n.Surname == Getsurname(MyLongListSelector2.SelectedItem.ToString()) && n.FirstName == GetFirstname(MyLongListSelector2.SelectedItem.ToString())
                              select n.Pic == null ? defaultPic : n.Pic).Single();

Where 'defaultPic' would be a string pointing to a default or no image pic.

You could also try String.IsNullOrEmpty to check if the Pic is null or empty, but i am not sure if it would work in Linq2SQL. I know it would in EF 6.x.

answered Jul 20, 2014 at 15:46

Giannis Paraskevopoulos

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1 Comment

EugenSunic Over a year ago

This entirely solves my problem. I didn't want to fill my database with a default image. I was thinking how I could point to one in a folder. tnx for the if-else(ternary) demonstration!

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