How to find all nodes in a namespace (LINQ to XML)

You can filter on the namespace of each element or attribute to find all nodes in that particular namespace.

Example: Create an XML tree with two namespaces, and print contents of one

The following example creates an XML tree with two namespaces. It then iterates through the tree and prints the names of all the elements and attributes in one of those namespaces.

string markup = @"<aw:Root xmlns:aw='http://www.adventure-works.com' xmlns:fc='www.fourthcoffee.com'>
  <fc:Child1>abc</fc:Child1>
  <fc:Child2>def</fc:Child2>
  <aw:Child3>ghi</aw:Child3>
  <fc:Child4>
    <fc:GrandChild1>jkl</fc:GrandChild1>
    <aw:GrandChild2>mno</aw:GrandChild2>
  </fc:Child4>
</aw:Root>";
XElement xmlTree = XElement.Parse(markup);
Console.WriteLine("Nodes in the http://www.adventure-works.com namespace");
IEnumerable<XElement> awElements =
    from el in xmlTree.Descendants()
    where el.Name.Namespace == "http://www.adventure-works.com"
    select el;
foreach (XElement el in awElements)
    Console.WriteLine(el.Name.ToString());

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

Module Module1
    Sub Main()
        Dim xmlTree As XElement = _
            <aw:Root>
                <fc:Child1>abc</fc:Child1>
                <fc:Child2>def</fc:Child2>
                <aw:Child3>ghi</aw:Child3>
                <fc:Child4>
                    <fc:GrandChild1>jkl</fc:GrandChild1>
                    <aw:GrandChild2>mno</aw:GrandChild2>
                </fc:Child4>
            </aw:Root>
        Console.WriteLine("Nodes in the http://www.adventure-works.com namespace")
        Dim awElements As IEnumerable(Of XElement) = _
            From el In xmlTree.Descendants() _
            Where (el.Name.Namespace = GetXmlNamespace(aw)) _
            Select el
        For Each el As XElement In awElements
            Console.WriteLine(el.Name.ToString())
        Next
    End Sub
End Module

This example produces the following output:

Nodes in the http://www.adventure-works.com namespace
{http://www.adventure-works.com}Child3
{http://www.adventure-works.com}GrandChild2

Example: Create an XML tree from one of two namespaces contained in a file

XML document Sample XML file: Consolidated purchase orders contains purchase orders in two different namespaces. The following query creates a new tree from the elements of one of them.

XDocument cpo = XDocument.Load("ConsolidatedPurchaseOrders.xml");
XNamespace aw = "http://www.adventure-works.com";
XElement newTree = new XElement("Root",
    from el in cpo.Root.Elements()
    where el.Name.Namespace == aw
    select el
);
Console.WriteLine(newTree);

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

Module Module1
    Sub Main()
        Dim cpo As XDocument = XDocument.Load("ConsolidatedPurchaseOrders.xml")
        Dim newTree As XElement = _
            <Root>
                <%= From el In cpo.Root.Elements() _
                    Where el.Name.Namespace = GetXmlNamespace(aw) _
                    Select el %>
            </Root>
        Console.WriteLine(newTree)
    End Sub
End Module

This example produces the following output:

<Root>
  <aw:PurchaseOrder PONumber="11223" Date="2000-01-15" xmlns:aw="http://www.adventure-works.com">
    <aw:ShippingAddress>
      <aw:Name>Chris Preston</aw:Name>
      <aw:Street>123 Main St.</aw:Street>
      <aw:City>Seattle</aw:City>
      <aw:State>WA</aw:State>
      <aw:Zip>98113</aw:Zip>
      <aw:Country>USA</aw:Country>
    </aw:ShippingAddress>
    <aw:BillingAddress>
      <aw:Name>Chris Preston</aw:Name>
      <aw:Street>123 Main St.</aw:Street>
      <aw:City>Seattle</aw:City>
      <aw:State>WA</aw:State>
      <aw:Zip>98113</aw:Zip>
      <aw:Country>USA</aw:Country>
    </aw:BillingAddress>
    <aw:DeliveryInstructions>Ship only complete order.</aw:DeliveryInstructions>
    <aw:Item PartNum="LIT-01">
      <aw:ProductID>Litware Networking Card</aw:ProductID>
      <aw:Qty>1</aw:Qty>
      <aw:Price>20.99</aw:Price>
    </aw:Item>
    <aw:Item PartNum="LIT-25">
      <aw:ProductID>Litware 17in LCD Monitor</aw:ProductID>
      <aw:Qty>1</aw:Qty>
      <aw:Price>199.99</aw:Price>
    </aw:Item>
  </aw:PurchaseOrder>
</Root>