Extensions.Ancestors(Of T) Method (IEnumerable(Of T), XName)

 

Returns a filtered collection of elements that contains the ancestors of every node 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)

<ExtensionAttribute>
Public Shared Function Ancestors(Of T As XNode) (
	source As IEnumerable(Of T),
	name As XName
) As IEnumerable(Of XElement)

Parameters

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

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

name
Type: System.Xml.Linq.XName

The XName to match.

Return Value

Type: System.Collections.Generic.IEnumerable(Of XElement)

An IEnumerable(Of T) of XElement that contains the ancestors of every node in the source collection. Only elements that have a matching XName are included in the collection.

Type Parameters

T

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

If multiple nodes in the source collection have the same ancestor with a matching XName, the ancestor will be included multiple times in the result collection.

This method uses deferred execution.

The following example retrieves a collection of the great grandchildren elements. It then uses this axis method to retrieve all ancestors of all elements in the collection that match a specified XName.


                Dim xmlTree As XElement = _
    <Root>
        <Child1>
            <GrandChild1>
                <GreatGrandChild1>content</GreatGrandChild1>
            </GrandChild1>
        </Child1>
        <Child2>
            <GrandChild2>
                <GreatGrandChild2>content</GreatGrandChild2>
            </GrandChild2>
        </Child2>
    </Root>

Dim greatGrandChildren = From el In xmlTree.Descendants _
                         Where el.Name.LocalName.StartsWith("Great") _
                         Select el

Console.WriteLine("Great Grand Children Elements")
Console.WriteLine("----")

For Each de As XElement In greatGrandChildren
    Console.WriteLine(de.Name)
Next

Dim allAncestors = From el In greatGrandChildren.Ancestors("Child1") _
                   Select el

Console.WriteLine("")
Console.WriteLine("Ancestors")
Console.WriteLine("----")

For Each de As XElement In allAncestors
    Console.WriteLine(de.Name)
Next

This example produces the following output:

Great Grand Children Elements
----
GreatGrandChild1
GreatGrandChild2

Ancestors
----
Child1

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>
                <Child1>
                    <GrandChild1>
                        <GreatGrandChild1>content</GreatGrandChild1>
                    </GrandChild1>
                </Child1>
                <Child2>
                    <GrandChild2>
                        <GreatGrandChild2>content</GreatGrandChild2>
                    </GrandChild2>
                </Child2>
            </Root>

        Dim greatGrandChildren = From el In xmlTree.Descendants _
                                 Where el.Name.LocalName.StartsWith("Great") _
                                 Select el

        Console.WriteLine("Great Grand Children Elements")
        Console.WriteLine("----")

        For Each de As XElement In greatGrandChildren
            Console.WriteLine(de.Name)
        Next

        Dim allAncestors = From el In greatGrandChildren.Ancestors(GetXmlNamespace() + "Child1") _
                           Select el

        Console.WriteLine("")
        Console.WriteLine("Ancestors")
        Console.WriteLine("----")

        For Each de As XElement In allAncestors
            Console.WriteLine(de.Name)
        Next
    End Sub
End Module

This example produces the following output:

Great Grand Children Elements
----
{http://www.adventure-works.com}GreatGrandChild1
{http://www.adventure-works.com}GreatGrandChild2

Ancestors
----
{http://www.adventure-works.com}Child1

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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