Extensions.Ancestors Method

Definition

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

Overloads

Ancestors<T>(IEnumerable<T>)

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

Ancestors<T>(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.

Remarks

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.

Ancestors<T>(IEnumerable<T>)

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

public static System.Collections.Generic.IEnumerable<System.Xml.Linq.XElement> Ancestors<T> (this System.Collections.Generic.IEnumerable<T> source) where T : System.Xml.Linq.XNode;
Type Parameters
T

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

Parameters
source
IEnumerable<T>

An IEnumerable<T> of XNode that contains the source collection.

Returns

An IEnumerable<T> of XElement that contains the ancestors of every node in the source collection.

Examples

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.

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.Ancestors().Distinct()  
    select el;  

Console.WriteLine("");  
Console.WriteLine("Ancestors");  
Console.WriteLine("----");  
foreach (XElement de in allAncestors)  
    Console.WriteLine(de.Name);  
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.Distinct _  
                   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  
----  
GrandChild1  
Child1  
Root  
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.Ancestors().Distinct()  
    select el;  

Console.WriteLine("");  
Console.WriteLine("Ancestors");  
Console.WriteLine("----");  
foreach (XElement de in allAncestors)  
    Console.WriteLine(de.Name);  
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.Distinct _  
                           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}GrandChild1  
{http://www.adventure-works.com}Child1  
{http://www.adventure-works.com}Root  
{http://www.adventure-works.com}GrandChild2  
{http://www.adventure-works.com}Child2  

Remarks

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.

See Also

Ancestors<T>(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.

public static System.Collections.Generic.IEnumerable<System.Xml.Linq.XElement> Ancestors<T> (this System.Collections.Generic.IEnumerable<T> source, System.Xml.Linq.XName name) where T : System.Xml.Linq.XNode;
Type Parameters
T

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

Parameters
source
IEnumerable<T>

An IEnumerable<T> of XNode that contains the source collection.

name
XName

The XName to match.

Returns

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.

Examples

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.

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.Ancestors("Child1")  
    select el;  

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

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.Ancestors(aw + "Child1")  
    select el;  

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

Remarks

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.

See Also

Applies to