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Extensions.AncestorsAndSelf Method (IEnumerable<XElement>)

Returns a collection of elements that contains every element in the source collection, and the ancestors of every element in the source collection.

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

public static IEnumerable<XElement> AncestorsAndSelf(
	this IEnumerable<XElement> source
)

Parameters

source
Type: System.Collections.Generic.IEnumerable<XElement>
An IEnumerable<T> of XElement that contains the source collection.

Return Value

Type: System.Collections.Generic.IEnumerable<XElement>
An IEnumerable<T> of XElement that contains every element in the source collection, and the ancestors of every 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<XElement>. 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).

If multiple nodes in the source collection have the same ancestor, the ancestor will be included multiple times in the result collection. To avoid this, use the Distinct method.

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 and self of all elements in the collection.

XElement xmlTree = new XElement("Root",
    new XElement("Child1",
        new XElement("GrandChild1",
            new XElement("GreatGrandChild1", "content")
        )
    ),
    new XElement("Child2",
        new XElement("GrandChild2",
            new XElement("GreatGrandChild2", "content")
        )
    )
);
IEnumerable<XElement> greatGrandChildren =
    from el in xmlTree.Descendants()
    where el.Name.LocalName.StartsWith("Great")
    select el;

Console.WriteLine("Great Grand Children Elements");
Console.WriteLine("----");
foreach (XElement de in greatGrandChildren)
    Console.WriteLine(de.Name);

IEnumerable<XElement> allAncestors =
    from el in greatGrandChildren.AncestorsAndSelf().Distinct()
    select el;

Console.WriteLine("");
Console.WriteLine("Ancestors and Self");
Console.WriteLine("----");
foreach (XElement de in allAncestors)
    Console.WriteLine(de.Name);

This example produces the following output:

Great Grand Children Elements
----
GreatGrandChild1
GreatGrandChild2

Ancestors and Self
----
GreatGrandChild1
GrandChild1
Child1
Root
GreatGrandChild2
GrandChild2
Child2

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 = new XElement(aw + "Root",
    new XElement(aw + "Child1",
        new XElement(aw + "GrandChild1",
            new XElement(aw + "GreatGrandChild1", "content")
        )
    ),
    new XElement(aw + "Child2",
        new XElement(aw + "GrandChild2",
            new XElement(aw + "GreatGrandChild2", "content")
        )
    )
);
IEnumerable<XElement> greatGrandChildren =
    from el in xmlTree.Descendants()
    where el.Name.LocalName.StartsWith("Great")
    select el;

Console.WriteLine("Great Grand Children Elements");
Console.WriteLine("----");
foreach (XElement de in greatGrandChildren)
    Console.WriteLine(de.Name);

IEnumerable<XElement> allAncestors =
    from el in greatGrandChildren.AncestorsAndSelf().Distinct()
    select el;

Console.WriteLine("");
Console.WriteLine("Ancestors and Self");
Console.WriteLine("----");
foreach (XElement de in allAncestors)
    Console.WriteLine(de.Name);

This example produces the following output:

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

Ancestors and Self
----
{http://www.adventure-works.com}GreatGrandChild1
{http://www.adventure-works.com}GrandChild1
{http://www.adventure-works.com}Child1
{http://www.adventure-works.com}Root
{http://www.adventure-works.com}GreatGrandChild2
{http://www.adventure-works.com}GrandChild2
{http://www.adventure-works.com}Child2

.NET Framework

Supported in: 4, 3.5

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

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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