How to: Filter on Element Names (LINQ to XML)

When you call one of the methods that return IEnumerable of XElement, you can filter on the element name.

Example

This example retrieves a collection of descendants that is filtered to contain only descendants with the specified name.

This example uses the following XML document: Sample XML File: Typical Purchase Order (LINQ to XML).

XElement po = XElement.Load("PurchaseOrder.xml");
IEnumerable<XElement> items =
    from el in po.Descendants("ProductName")
    select el;
foreach(XElement prdName in items)
    Console.WriteLine(prdName.Name + ":" + (string) prdName);

Dim po As XElement = XElement.Load("PurchaseOrder.xml")
Dim items As IEnumerable(Of XElement) = _
    From el In po...<ProductName> _
    Select el
For Each prdName As XElement In items
    Console.WriteLine(prdName.Name.ToString & ":" & prdName.Value)
Next

This code produces the following output:

ProductName:Lawnmower
ProductName:Baby Monitor

The other methods that return IEnumerable of XElement collections follow the same pattern. Their signatures are similar to Elements and Descendants. The following is the complete list of methods that have similar method signatures:

• Ancestors

• Descendants

• Elements

• ElementsAfterSelf

• ElementsBeforeSelf

• AncestorsAndSelf

• DescendantsAndSelf

The following example shows the same query for XML that is in a namespace. For more information, see Working with XML Namespaces.

This example uses the following XML document: Sample XML File: Typical Purchase Order in a Namespace.

XNamespace aw = "https://www.adventure-works.com";
XElement po = XElement.Load("PurchaseOrderInNamespace.xml");
IEnumerable<XElement> items =
    from el in po.Descendants(aw + "ProductName")
    select el;
foreach (XElement prdName in items)
    Console.WriteLine(prdName.Name + ":" + (string)prdName);

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

Module Module1
    Sub Main()
        Dim po As XElement = XElement.Load("PurchaseOrderInNamespace.xml")
        Dim items As IEnumerable(Of XElement) = _
            From el In po...<aw:ProductName> _
            Select el
        For Each prdName As XElement In items
            Console.WriteLine(prdName.Name.ToString & ":" & prdName.Value)
        Next
    End Sub
End Module

This code produces the following output:

{https://www.adventure-works.com}ProductName:Lawnmower
{https://www.adventure-works.com}ProductName:Baby Monitor

See Also

Concepts

LINQ to XML Axes

Build Date:

2012-08-02