Partager via

  • Article

Extensions.Elements<T> Method (IEnumerable<T>, XName)

Microsoft Silverlight will reach end of support after October 2021. Learn more.

Returns a filtered collection of the child elements of every element and document 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)

Syntax

'Declaration
<ExtensionAttribute> _
Public Shared Function Elements(Of T As XContainer) ( _
    source As IEnumerable(Of T), _
    name As XName _
) As IEnumerable(Of XElement)

public static IEnumerable<XElement> Elements<T>(
    this IEnumerable<T> source,
    XName name
)
where T : XContainer

Type Parameters

  • T
    The type of the objects in source, constrained to XContainer.

Parameters

Return Value

Type: System.Collections.Generic.IEnumerable<XElement>
An IEnumerable<T> of XElement of the child elements of every element and document 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.

Exceptions

Exception Condition
ArgumentNullException

source is nulla null reference (Nothing in Visual Basic).

Remarks

Visual Basic users can use the integrated elements axis to retrieve the child elements of every element in a collection.

This method uses deferred execution.

Examples

This extension method is useful when you want to retrieve all elements with a specified name at a particular depth. This is easy if the document is very regular, but if the document is irregular, it can be a bit more difficult. In the following example, we want to retrieve all aaa elements that are children of Item elements. A given Item element may or may not contain an aaa element. This is easily accomplished using this extension method, as follows:

Dim output As New StringBuilder
Dim xmlTree As XElement = _
    <Root>
        <Item>
            <aaa>1</aaa>
            <bbb>2</bbb>
        </Item>

        <Item>
            <ccc>3</ccc>
            <aaa>4</aaa>
        </Item>

        <Item>
            <ddd>5</ddd>
            <eee>6</eee>
        </Item>
    </Root>

Dim allGrandChildren = From el In xmlTree.<Item>.<aaa> _
                       Select el

For Each el As XElement In allGrandChildren
    output.Append(el)
    output.Append(Environment.NewLine)
Next


OutputTextBlock.Text = output.ToString()

StringBuilder output = new StringBuilder();
XElement xmlTree = new XElement("Root",
    new XElement("Item",
        new XElement("aaa", 1),
        new XElement("bbb", 2)
    ),
    new XElement("Item",
        new XElement("ccc", 3),
        new XElement("aaa", 4)
    ),
    new XElement("Item",
        new XElement("ddd", 5),
        new XElement("eee", 6)
    )
);

IEnumerable<XElement> allGrandChildren =
    from el in xmlTree.Elements("Item").Elements("aaa")
    select el;

foreach (XElement el in allGrandChildren)
    output.Append(el + Environment.NewLine);

OutputTextBlock.Text = output.ToString();

Version Information

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

Platforms

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