Extensions.Descendants<T> Method (IEnumerable<T>, XName)

Returns a filtered collection of elements that contains the descendant elements of every element and document in the source collection. Only elements that have a matching XName are included in the collection.

Namespace:  System.Xml.Linq
Assembly:  System.Xml.Linq (in System.Xml.Linq.dll)

public static IEnumerable<XElement> Descendants<T>(
	this IEnumerable<T> source,
	XName name
)
where T : XContainer

Type Parameters

T

The type of the objects in source, constrained to XContainer.

Parameters

source
Type: System.Collections.Generic.IEnumerable<T>

An IEnumerable<T> of XContainer that contains the source collection.

name
Type: System.Xml.Linq.XName

The XName to match.

Return Value

Type: System.Collections.Generic.IEnumerable<XElement>
An IEnumerable<T> of XElement that contains the descendant elements of every element and document in the source collection. Only elements that have a matching XName are included in the collection.

Usage Note

In Visual Basic and C#, you can call this method as an instance method on any object of type IEnumerable<T>. When you use instance method syntax to call this method, omit the first parameter. For more information, see Extension Methods (Visual Basic) or Extension Methods (C# Programming Guide).

Visual Basic users can use the Language-Integrated Axes in Visual Basic (LINQ to XML) instead of using this axis method explicitly.

This method uses deferred execution.

The following example retrieves a collection of two elements, and then retrieves a collection of all descendants of the two elements that have the specified element name.

XElement xmlTree = XElement.Parse(
@"<Root>
    <Para>
        <t>This is some text </t>
        <b>
            <t>where</t>
        </b>
        <t> all of the text nodes must be concatenated. </t>
    </Para>
    <Para>
        <t>This is a second sentence.</t>
    </Para>
</Root>");

string str =
    (from el in xmlTree.Elements("Para").Descendants("t")
    select (string)el)
    .Aggregate(new StringBuilder(),
        (sb, i) => sb.Append(i),
        sb => sb.ToString());

Console.WriteLine(str);

This example produces the following output:

This is some text where all of the text nodes must be concatenated. This is a second sentence.

The following is the same example, but in this case the XML is in a namespace. For more information, see Working with XML Namespaces.

XNamespace aw = "http://www.adventure-works.com";
XElement xmlTree = XElement.Parse(
@"<Root xmlns='http://www.adventure-works.com'>
    <Para>
        <t>This is some text </t>
        <b>
            <t>where</t>
        </b>
        <t> all of the text nodes must be concatenated. </t>
    </Para>
    <Para>
        <t>This is a second sentence.</t>
    </Para>
</Root>");

string str =
    (from el in xmlTree.Elements(aw + "Para").Descendants(aw + "t")
     select (string)el)
    .Aggregate(new StringBuilder(),
        (sb, i) => sb.Append(i),
        sb => sb.ToString());

Console.WriteLine(str);

This example produces the following output:

This is some text where all of the text nodes must be concatenated. This is a second sentence.

Windows 7, Windows Vista, Windows XP SP2, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003, Windows CE, Windows Mobile for Smartphone, Windows Mobile for Pocket PC, Xbox 360, Zune

The .NET Framework and .NET Compact Framework do not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

.NET Framework

Supported in: 3.5

.NET Compact Framework

Supported in: 3.5

XNA Framework

Supported in: 3.0
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