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Extensions.Ancestors<T> Method (IEnumerable<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)

public static IEnumerable<XElement> Ancestors<T>(
	this IEnumerable<T> source,
	XName name
)
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.
name
Type: System.Xml.Linq.XName
The XName to match.

Return Value

Type: System.Collections.Generic.IEnumerable<XElement>
An IEnumerable<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.

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 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.



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("Child1")
    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();


Silverlight

Supported in: 5, 4, 3

Silverlight for Windows Phone

Supported in: Windows Phone OS 7.1, Windows Phone OS 7.0

XNA Framework

Supported in: Xbox 360, Windows Phone OS 7.0

For a list of the operating systems and browsers that are supported by Silverlight, see Supported Operating Systems and Browsers.

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