Extensions.DescendantNodes(Of T) Method (IEnumerable(Of T))

 

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)

<ExtensionAttribute>
Public Shared Function DescendantNodes(Of T As XContainer) (
	source As IEnumerable(Of T)
) As IEnumerable(Of XNode)

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.

Type Parameters

T

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

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

Universal Windows Platform
Available since 8
.NET Framework
Available since 3.5
Portable Class Library
Supported in: portable .NET platforms
Silverlight
Available since 2.0
Windows Phone Silverlight
Available since 7.0
Windows Phone
Available since 8.1
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