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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.

ExceptionCondition
ArgumentNullException

source is Nothing.

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 output As New StringBuilder
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

output.Append("Great Grand Children Elements")
output.Append(Environment.NewLine)
output.Append("----")
output.Append(Environment.NewLine)

For Each de As XElement In greatGrandChildren
    output.Append(de.Name)
    output.Append(Environment.NewLine)
Next

Dim allAncestors = From el In greatGrandChildren.Ancestors.Distinct _
                   Select el

output.Append("")
output.Append(Environment.NewLine)

output.Append("Ancestors")
output.Append(Environment.NewLine)
output.Append("----")
output.Append(Environment.NewLine)

For Each de As XElement In allAncestors
    output.Append(de.Name)
    output.Append(Environment.NewLine)
Next

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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