Ancestors(T) Method (IEnumerable(T))
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Extensions.Ancestors<T> Method (IEnumerable<T>)

[ This article is for Windows Phone 8 developers. If you’re developing for Windows 10, see the latest documentation. ]

Returns a collection of elements that contains the ancestors of every node in the source collection.

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

public static IEnumerable<XElement> Ancestors<T>(
	this IEnumerable<T> source
)
where T : XNode

Type Parameters

T

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

Parameters

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

Return Value

Type: System.Collections.Generic.IEnumerable<XElement>
An IEnumerable<T> of XElement that contains the ancestors of every node 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<T>. When you use instance method syntax to call this method, omit the first parameter.

ExceptionCondition
ArgumentNullException

source is null.

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 of all elements in the collection.


StringBuilder output = new StringBuilder();
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;

output.Append("Great Grand Children Elements" + Environment.NewLine);
output.Append("----" + Environment.NewLine);
foreach (XElement de in greatGrandChildren)
    output.Append(de.Name + Environment.NewLine);

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

output.Append("" + Environment.NewLine);
output.Append("Ancestors" + Environment.NewLine);
output.Append("----" + Environment.NewLine);
foreach (XElement de in allAncestors)
    output.Append(de.Name + Environment.NewLine);

OutputTextBlock.Text = output.ToString();


Windows Phone OS

Supported in: 8.1, 8.0, 7.1, 7.0

Windows Phone

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