Query an XDocument for elements by name at any depth

I have an XDocument object. I want to query for elements with a particular name at any depth using LINQ.

When I use Descendants("element_name"), I only get elements that are direct children of the current level. I'm looking for the equivalent of "//element_name" in XPath...should I just use XPath, or is there a way to do it using LINQ methods?

Solution 1:

Descendants should work absolutely fine. Here's an example:

using System;
using System.Xml.Linq;

class Test
{
    static void Main()
    {
        string xml = @"
<root>
  <child id='1'/>
  <child id='2'>
    <grandchild id='3' />
    <grandchild id='4' />
  </child>
</root>";
        XDocument doc = XDocument.Parse(xml);

        foreach (XElement element in doc.Descendants("grandchild"))
        {
            Console.WriteLine(element);
        }
    }
}

Results:

<grandchild id="3" />
<grandchild id="4" />

Solution 2:

An example indicating the namespace:

String TheDocumentContent =
@"
<TheNamespace:root xmlns:TheNamespace = 'http://www.w3.org/2001/XMLSchema' >
   <TheNamespace:GrandParent>
      <TheNamespace:Parent>
         <TheNamespace:Child theName = 'Fred'  />
         <TheNamespace:Child theName = 'Gabi'  />
         <TheNamespace:Child theName = 'George'/>
         <TheNamespace:Child theName = 'Grace' />
         <TheNamespace:Child theName = 'Sam'   />
      </TheNamespace:Parent>
   </TheNamespace:GrandParent>
</TheNamespace:root>
";

XDocument TheDocument = XDocument.Parse( TheDocumentContent );

//Example 1:
var TheElements1 =
from
    AnyElement
in
    TheDocument.Descendants( "{http://www.w3.org/2001/XMLSchema}Child" )
select
    AnyElement;

ResultsTxt.AppendText( TheElements1.Count().ToString() );

//Example 2:
var TheElements2 =
from
    AnyElement
in
    TheDocument.Descendants( "{http://www.w3.org/2001/XMLSchema}Child" )
where
    AnyElement.Attribute( "theName" ).Value.StartsWith( "G" )
select
    AnyElement;

foreach ( XElement CurrentElement in TheElements2 )
{
    ResultsTxt.AppendText( "\r\n" + CurrentElement.Attribute( "theName" ).Value );
}

Solution 3:

You can do it this way:

xml.Descendants().Where(p => p.Name.LocalName == "Name of the node to find")

where xml is a XDocument.

Be aware that the property Name returns an object that has a LocalName and a Namespace. That's why you have to use Name.LocalName if you want to compare by name.

Solution 4:

Descendants will do exactly what you need, but be sure that you have included a namespace name together with element's name. If you omit it, you will probably get an empty list.