Return empty string using Linq to SQL - Related table with no rows - ASP.Net MVC

Question

I have 1 to many relationship with the following tables - Person and Email. When using linq to sql and ASP.Net MVC, I'd like to show the first email or an empty string in my Person view using code like this:

<%= Html.Encode(Model.Emails.FirstOrDefault().EmailAddress) %>

In cases where there are no email rows, I receive a NullReferenceException. I can return null safe values from SQL by using a view or sproc, but I'd like to just stick with generic linq to sql objects bound to tables.

score 8 · Accepted Answer · answered Feb 24 '10 at 22:48

8

Model.Emails.Select(x => x.EmailAddress).FirstOrDefault() ?? string.Empty

answered Feb 24 '10 at 22:48

Mark Byers

811,555
193
1,581
1,452

score 1 · Answer 2 · answered Feb 24 '10 at 22:48

1

<%= Html.Encode((Model.Emails.FirstOrDefault() ?? new Email { EmailAddress = string.Empty }).EmailAddress) %>

Would work, not super clean to read though.

answered Feb 24 '10 at 22:48

Quintin Robinson

81,193
14
123
132

Thanks for your answer, the above is nearly the same but just a bit more concise – jlnorsworthy Feb 24 '10 at 23:06
This is better than others. 'cause Select methods is looping on all emails and its not good choose for performance. – cem Feb 25 '10 at 01:09

Andrew · Answer 3 · 2010-02-24T23:04:11.163

My vote for:

Model.Emails.Select(z => z.EmailAddress).DefaultIfEmpty("zzz").FirstOrDefault();

I thought that you could do it all inside the FirstOrDefault, but I was wrong-o! However, I also forgot that when you use DefaultIfEmpty you can just call First().

Model.Emails.Select(z => z.EmailAddress).DefaultIfEmpty("zzz").First();

Of course, replace ZZZ with just "" (not string.empty, that is unnecessary), but it is nice to see those records where the default is being chosen explicity when you are first writing it.

Return empty string using Linq to SQL - Related table with no rows - ASP.Net MVC

3 Answers3