Question

Hi i am doing as follow

 XDocument xmlDoc = XDocument.Load(@"F:\test2.xml");
        var q = from c in xmlDoc.Descendants("autoivr.ok")
                where c.Element("LS_CZIP4").Value == "1234"
                select new
                {
                    name = c.Element("LS_LIN").Value,
                    state = c.Element("LS_STATE").Value                        
                };

When i use
where c.attribute(“LS_CZIP4”).Value == “1234”
i get error of object reference not set but when i use c.element there is no such error.

Following is the xml i made which is actually a table in sql converted to xml file

<?xml version="1.0" standalone="yes"?>
<DocumentElement>
   <autoivr.ok>
      <LS_LIN>abc</LS_LIN>
      <LS_STATE>def</LS_STATE>
      <LS_TYPE>5</LS_TYPE>
      <LS_CZIP4>1234</LS_CZIP4>
   <priority>0</priority>
   </autoivr.ok>

Can someone let me know the problem and how can i resolve and can i work with element tag only instead of attribute . Thank You

Answer 1

Use casting instead of accessing Value property. Casting to string will return null for non-existing elements. Getting Value will throw an exception

XDocument xmlDoc = XDocument.Load(@"F:\test2.xml");
var q = from c in xmlDoc.Descendants("autoivr.ok")
        where (string)c.Element("LS_CZIP4") == "1234"
        select new
        {
            name = (string)c.Element("LS_LIN"),
            state = (string)c.Element("LS_STATE")
        };

BTW you need closing tag for <DocumentElement>. Also LS_CZIP4 is element, not attribute. See the difference here XML Elements vs. Attributes.

Element: <LS_LIN>abc</LS_LIN>

Attribute: <autoivr.ok LS_LIN="abc">