C# ?? null coalescing operator LINQ

Question

I am trying to prevent having NULL values when I parse an XML file to a custom object using LINQ.

I found a great solution for this on Scott Gu's blog, but for some reason it does not work for integers with me. I think I have used the same syntax but it seems I am missing something. Oh and for some reason it works when the node is not empty.

Below is an extract of my code.

List<GrantAgresso> lsResult = (from g in xml.Element("root").Elements("Elementname")
        select new GrantAgresso()
        {
             Year = (int?)g.Element("yearnode") ?? 0,
             Subdomain = (string)g.Element("domainnode") ?? ""
        }).ToList();

The errormessage is:

Input string was not in a correct format.

If anyone has a clue as to what I'm doing wrong, please help :)

Edit: piece of XML (strange names but it's not by choice)

<Agresso>
  <AgressoQE>
    <r3dim_value>2012</r3dim_value>
    <r0r0r0dim_value>L5</r0r0r0dim_value>
    <r7_x0023_province_x0023_69_x0023_V005>0</r7_x0023_province_x0023_69_x0023_V005>
    <r7_x0023_postal_code_x0023_68_x0023_V004 />
    <r7_x0023_country_x0023_67_x0023_V003>1004</r7_x0023_country_x0023_67_x0023_V003>
    <r7_x0023_communitydistrict_x0023_70_x0023_V006>0</r7_x0023_communitydistrict_x0023_70_x0023_V006>
  </AgressoQE>
</Agresso>

Answer 1

It is this expression which is throwing:

(int?)g.Element("yearnode")

That's because if the actual value of the element's text node is String.Empty and not null, since the empty string is not a valid format for Int32.Parse, the attempted cast fails.

If the element is missing completely from your XML, this works as you expect, but if there is an empty tag <yearnode/> or <yearnode></yearnode>, you'll get the exception.