LINQ : Check for NullReferenceException

Question

In the following code, How can I check for null reference exception in a "good practice" way?

if (primaryMenu.ChildNodes.Any(p=>VirtualPathUtility.GetFileName(p.SiteURL).Equals(selectedPage)))
{
   primaryMenuTab.Attributes.Add("class", "current");
}

The way I am doing it currently is (But JetBrain ReSharper doesnt't wana accept it and keep warning me on the following part : VirtualPathUtility.GetFileName(p.SiteURL) which is understandable),

if (primaryMenu.ChildNodes.Any(p=> p.SiteURL != null && VirtualPathUtility.GetFileName(p.SiteURL).Equals(selectedPage)))
{
   primaryMenuTab.Attributes.Add("class", "current");
}

Where Menus have the following structure,

public class MultiLevelMenuNodeList
 {
  public string Name { get; set; }
  public string Permission { get; set; }
  public string SiteURL { get; set; }
  public string Visibility { get; set; }
  public List<SingleLevelMenuNodeList> ChildNodes { get; set; }
 }

 public class SingleLevelMenuNodeList
 {
  public string Name { get; set; }
  public string Permission { get; set; }
  public string SiteURL { get; set; }
  public string Visibility { get; set; }
  public string TabPosition { get; set; }
 }

Thanks in advance for suggestions and tips. I am kinda getting addicted to stackoverflow:)

what is the warning that is displayed by resharper?

shahkalpesh
– shahkalpesh

2010-08-18 06:38:14 +00:00
Commented Aug 18, 2010 at 6:38 — shahkalpesh
– shahkalpesh, Commented Aug 18, 2010 at 6:38

Jon Skeet · Accepted Answer · 2010-08-18 06:47:44Z

3

A simple solution is to just use == which is null-safe:

if (primaryMenu.ChildNodes.Any(p =>
        VirtualPathUtility.GetFileName(p.SiteURL) == selectedPage))

(That's assuming GetFileName itself can cope with null input; otherwise put your first null check back in.)

edited Aug 18, 2010 at 6:47

answered Aug 18, 2010 at 6:40

Jon Skeet

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2 Comments

MSI Over a year ago

@shashkalpesh it shows Possible 'System.NullReferenceException' @Jon Thanks :) I will use that and see how it goes.

MSI Over a year ago

Yup ReSharper is not showing any warning when I use ==. Thanks

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