Extensions.Ancestors(Of T) Method (IEnumerable(Of T))
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)
'Declaration <ExtensionAttribute> _ Public Shared Function Ancestors(Of T As XNode) ( _ source As IEnumerable(Of T) _ ) As IEnumerable(Of XElement)
Type Parameters
- T
The type of the objects in source, constrained to XNode.
Parameters
- source
- Type: System.Collections.Generic.IEnumerable(Of T)
An IEnumerable(Of T) of XNode that contains the source collection.
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.
Usage Note
In Visual Basic and C#, you can call this method as an instance method on any object of type IEnumerable(Of T). 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 of all elements in the collection.
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.
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
Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)
The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.
