Dealing with Null values in a database when using linq.

Posted on 2014-02-18
Last Modified: 2016-02-10
I have a list of cost centers that I want to grab. My DB Admin allows nulls for one of my fields. I can't seem to get around this. What can I do?? How do I get around this? Right now my error is "Unable to cast the type 'System.Nullable`1' to type 'System.Object'. LINQ to Entities only supports casting EDM primitive or enumeration types."

    public class CostCenter
        public string DepartmentID { get; set; }
        public string ModelName { get; set; }

List<CostCenter> DList = new List<CostCenter>();
                DList = (from x in ctx.Inventory where x.CostCenterID != null
                         select new CostCenter { ModelName = x.CostCenterID + "-" + x.ModelName, DepartmentID = SqlFunctions.StringConvert((double)(x.CostCenterID ?? 1)) }).Distinct().ToList();

Open in new window

Question by:NickMalloy
  • 2
  • 2
  • 2
LVL 21

Expert Comment

by:Craig Wagner
ID: 39868036
I'm assuming the CostCenterID is the column that allows null? I'm not sure why you're having any trouble with it because your "where" clause eliminates any rows where the CostCenterID is null.

What is the actual datatype of CostCenterID in the database? Your casting and conversions in the Select seem entirely unnecessary. You've already eliminated any row where the CostCenterID is null, so why is the null coalesce (i.e. ??) necessary?

Author Comment

ID: 39868722
I started going down that route because of the traditional can't convert ?int to int.
LVL 21

Expert Comment

by:Craig Wagner
ID: 39868851
I'm afraid that doesn't give me enough information to provide any further assistance. If you still need help please see the rest of my questions from the first post and provide answers. Thanks.
6 Surprising Benefits of Threat Intelligence

All sorts of threat intelligence is available on the web. Intelligence you can learn from, and use to anticipate and prepare for future attacks.


Expert Comment

ID: 39869993
If the CostCenterID is an numeric datatype, then you need to use:

where x.CostCenterID.HasValue

Author Comment

ID: 39870427
I'm trying to get ride of the error.

cannot implicitly convert type 'int? ' to 'int'

I've tried several ways, but don't know how to get around it. CostCenterID allows nulls.

Current Code

List<CostCenter> DList = new List<CostCenter>();
DList = (from x in ctx.Inventory where x.CostCenterID.HasValue
                         select new CostCenter { ModelName = x.CostCenterID + "-" + x.ModelName, DepartmentID = x.CostCenterID }).Distinct().ToList();

Open in new window


Accepted Solution

DaveKeyes earned 500 total points
ID: 39873844
Use the following to retrieve the value from a nullable int:

ModelName = x.CostCenterID.Value

Featured Post

Threat Intelligence Starter Resources

Integrating threat intelligence can be challenging, and not all companies are ready. These resources can help you build awareness and prepare for defense.

Join & Write a Comment

Suggested Solutions

Title # Comments Views Activity
Voice recognition ASP or ASP.NET or JavaScript 2 45
LINQ question 7 22
Hovering effect 9 29
dynamic menu in c# 11 30
AJAX ModalPopupExtender has a required property "TargetControlID" which may seem to be very confusing to new users. It means the server control that will be extended by the ModalPopup, for instance, if when you click a button, a ModalPopup displays,…
I have developed many web applications with asp & and to add and use a dropdownlist was always a very simple task, but with the new, setting the value is a bit tricky and its not similar to the old traditional method. So in this a…
In this seventh video of the Xpdf series, we discuss and demonstrate the PDFfonts utility, which lists all the fonts used in a PDF file. It does this via a command line interface, making it suitable for use in programs, scripts, batch files — any pl…
Here's a very brief overview of the methods PRTG Network Monitor ( offers for monitoring bandwidth, to help you decide which methods you´d like to investigate in more detail.  The methods are covered in more detail in o…

758 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question

Need Help in Real-Time?

Connect with top rated Experts

20 Experts available now in Live!

Get 1:1 Help Now