Extensions.Elements Method (System.Xml.Linq) (original) (raw)

Source:

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.

public:
generic <typename T>
 where T : System::Xml::Linq::XContainer[System::Runtime::CompilerServices::Extension]
 static System::Collections::Generic::IEnumerable<System::Xml::Linq::XElement ^> ^ Elements(System::Collections::Generic::IEnumerable<T> ^ source, System::Xml::Linq::XName ^ name);

public static System.Collections.Generic.IEnumerable<System.Xml.Linq.XElement> Elements<T>(this System.Collections.Generic.IEnumerable<T> source, System.Xml.Linq.XName name) where T : System.Xml.Linq.XContainer;

public static System.Collections.Generic.IEnumerable<System.Xml.Linq.XElement> Elements<T>(this System.Collections.Generic.IEnumerable<T?> source, System.Xml.Linq.XName? name) where T : System.Xml.Linq.XContainer;

static member Elements : seq<'T (requires 'T :> System.Xml.Linq.XContainer)> * System.Xml.Linq.XName -> seq<System.Xml.Linq.XElement> (requires 'T :> System.Xml.Linq.XContainer)

<Extension()>
Public Function Elements(Of T As XContainer) (source As IEnumerable(Of T), name As XName) As IEnumerable(Of XElement)

Type Parameters

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

Parameters

Returns

An IEnumerable 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.

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:

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)  
    Console.WriteLine(el);

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  
    Console.WriteLine(el)  
Next

This example produces the following output:

<aaa>1</aaa>  
<aaa>4</aaa>

The following is the same example, but in this case the XML is in a namespace. For more information, see Work with XML Namespaces.

XNamespace aw = "http://www.adventure-works.com";  
XElement xmlTree = new XElement(aw + "Root",  
    new XElement(aw + "Item",  
        new XElement(aw + "aaa", 1),  
        new XElement(aw + "bbb", 2)  
    ),  
    new XElement(aw + "Item",  
        new XElement(aw + "ccc", 3),  
        new XElement(aw + "aaa", 4)  
    ),  
    new XElement(aw + "Item",  
        new XElement(aw + "ddd", 5),  
        new XElement(aw + "eee", 6)  
    )  
);  

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

foreach (XElement el in allGrandChildren)  
    Console.WriteLine(el);

Imports <xmlns="http://www.adventure-works.com">  

Module Module1  
    Sub Main()  
        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  
            Console.WriteLine(el)  
        Next  
    End Sub  
End Module

This example produces the following output:

<aaa xmlns="http://www.adventure-works.com">1</aaa>  
<aaa xmlns="http://www.adventure-works.com">4</aaa>

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.