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Extensions.DescendantNodes(Of T) Method

Returns a collection of the descendant nodes of every document and element in the source collection.

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

'Declaration
<ExtensionAttribute> _
Public Shared Function DescendantNodes(Of T As XContainer) ( _
	source As IEnumerable(Of T) _
) As IEnumerable(Of XNode)

Type Parameters

T

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

Parameters

source
Type: System.Collections.Generic.IEnumerable(Of T)

An IEnumerable(Of T) of XContainer that contains the source collection.

Return Value

Type: System.Collections.Generic.IEnumerable(Of XNode)
An IEnumerable(Of T) of XNode of the descendant nodes of every document and element in the source collection.

Usage Note

In Visual Basic and C#, you can call this method as an instance method on any object of type IEnumerable(Of 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).

This axis extension method is used on XDocument and XElement objects. Both of these types derive from XContainer, so this method operates on an IEnumerable(Of T) of XContainer that contains the source collection.

Although Visual Basic has an integrated XML axis for descendant elements, there is no integrated axis for descendant nodes, so Visual Basic users must use 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 descendant nodes for every element in the source collection. Note that the attribute of the GrandChild element is not surfaced as a node.

Dim xmlTree As XElement = _
<Root>
    <Child>aaa<GrandChild anAttribute='xyz'>Text</GrandChild>
        <!--a comment-->
        <?xml-stylesheet type='text/xsl' href='test.xsl'?>
    </Child>
    <Child>ccc<GrandChild>Text</GrandChild>ddd</Child>
</Root>

Dim nodes As IEnumerable(Of XNode) = _
    From node In xmlTree.<Child>.DescendantNodes _
    Select node

For Each node As XNode In nodes
    Select Case node.NodeType
        Case XmlNodeType.Element
            Console.WriteLine("Element: {0}", DirectCast(node, XElement).Name)
        Case XmlNodeType.Text
            Console.WriteLine("Text: {0}", DirectCast(node, XText).Value)
        Case XmlNodeType.Comment
            Console.WriteLine("Comment: {0}", DirectCast(node, XComment).Value)
        Case XmlNodeType.ProcessingInstruction
            Console.WriteLine("PI: {0}", DirectCast(node, XProcessingInstruction).Data)
    End Select
Next

This example produces the following output:

Text: aaa
Element: GrandChild
Text: Text
Comment: a comment
PI: type='text/xsl' href='test.xsl'
Text: ccc
Element: GrandChild
Text: Text
Text: ddd

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

Imports <xmlns="http://www.adventure-works.com">

Module Module1
    Sub Main()
        Dim xmlTree As XElement = _
        <Root>
            <Child>aaa<GrandChild anAttribute='xyz'>Text</GrandChild>
                <!--a comment-->
                <?xml-stylesheet type='text/xsl' href='test.xsl'?>
            </Child>
            <Child>ccc<GrandChild>Text</GrandChild>ddd</Child>
        </Root>

        Dim nodes As IEnumerable(Of XNode) = _
            From node In xmlTree.<Child>.DescendantNodes _
            Select node

        For Each node As XNode In nodes
            Select Case node.NodeType
                Case XmlNodeType.Element
                    Console.WriteLine("Element: {0}", DirectCast(node, XElement).Name)
                Case XmlNodeType.Text
                    Console.WriteLine("Text: {0}", DirectCast(node, XText).Value)
                Case XmlNodeType.Comment
                    Console.WriteLine("Comment: {0}", DirectCast(node, XComment).Value)
                Case XmlNodeType.ProcessingInstruction
                    Console.WriteLine("PI: {0}", DirectCast(node, XProcessingInstruction).Data)
            End Select
        Next
    End Sub
End Module

This example produces the following output:

Text: aaa
Element: {http://www.adventure-works.com}GrandChild
Text: Text
Comment: a comment
PI: type='text/xsl' href='test.xsl'
Text: ccc
Element: {http://www.adventure-works.com}GrandChild
Text: Text
Text: ddd

.NET Framework

Supported in: 4.5, 4, 3.5

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Portable Class Library

Supported in: Portable Class Library

.NET for Windows Store apps

Supported in: Windows 8

.NET for Windows Phone apps

Supported in: Windows Phone 8.1, Windows Phone Silverlight 8.1, Windows Phone Silverlight 8

Windows Phone 8.1, Windows Phone 8, Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)

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

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