Question

Getting a warning on “!redirectsDictionary.ContainsKey(autoRedirect.Key)”

asp.net possible null assignment to entity marked with “notnull” attribute.

Just wondering what that’s about ?

private static readonly Dictionary<string, Redirect> AutoRedirectsDictionary = new Dictionary<string, Redirect>();

foreach (var r in db.SelectItems("fast:/sitecore/content/Redirects Root//*[@@templatename='Auto Redirect']"))
        {
            GenerateRedirects(Context.Database.GetItem(r.Fields["Root Node"].Value), r["URL Prefix"]);
            foreach (var autoRedirect in AutoRedirectsDictionary)
            {
                if (!string.IsNullOrEmpty(autoRedirect.Key) & !redirectsDictionary.ContainsKey(autoRedirect.Key))
                {
                    //Add to dictionary
                    redirectsDictionary.Add(autoRedirect.Key, autoRedirect.Value);
                }

            }
        }

public static void GenerateRedirects(Item redirectFolder, string urlPrefix)
        {
            if (redirectFolder == null)
                return;

            var childList = redirectFolder.GetChildren();

            foreach (Item child in childList)
            {
                if (Utilities.HasFieldValue(child, FieldToFind))
                {
                    var shortcutUrl = urlPrefix + child.Fields[FieldToFind].Value.ToLower();

                    if (!string.IsNullOrEmpty(shortcutUrl) && !AutoRedirectsDictionary.ContainsKey(shortcutUrl))
                    {
                        AutoRedirectsDictionary.Add(shortcutUrl,
                        new Redirect(String.Empty, child, true));       
                    }
                }
                else
                {
                    GenerateRedirects(child, urlPrefix);
                }
            }
        }

Answer 1

It might have to do with your use of the single & operator. A single & will not use short-circuiting to bypass a statement but will instead choose the path to execute after all expressions have been evaluated. So even though you’re checking !string.IsNullOrEmpty(autoRedirect.Key) prior to the ContainsKey call, both expressions will be evaluated first and then the path of execution will be decided.

Edited as I realized I didn’t truly answer your specific question (and you may already know this) but !redirectsDictionary.ContainsKey(autoRedirect.Key) will throw an exception if the key is null. Since the datatype for the key is a string there is a possibility it will throw an exception if it is null, hence the warning.