LINQ Pocket Reference

LINQ to XML

The .NET Framework provides a number of APIs for working with XML data. From Framework 3.5, the primary choice for general-purpose XML document processing is LINQ to XML. LINQ to XML comprises a lightweight LINQ-friendly XML document object model, and a set of supplementary query operators. In most scenarios, it can be considered a complete replacement for the preceding W3C-compliant DOM, a.k.a. XmlDocument.

Note

The LINQ to XML DOM is extremely well designed and highly performant. Even without LINQ, the LINQ to XML DOM is valuable as a lightweight facade over the low-level XmlReader and XmlWriter classes.

All LINQ to XML types are defined in the System.Xml.Linq namespace.

Architectural Overview

Consider the following XML file:

	<?xml version="1.0" encoding="utf-8" standalone="yes"?>
	<customer id="123" status="archived">
	  <firstname>Joe</firstname>
	  <lastname>Bloggs</lastname>
	</customer>

As with all XML files, we start with a declaration, and then a root element, whose name is customer. The customer element has two attributes, each with a name (id and status ) and value ("123" and "archived" ). Within customer, there are two child elements, firstname and lastname, each having simple text content ("Joe" and "Bloggs" ).

Each of these constructs—declaration, element, attribute, value, and text content—can be represented with a class. And if such classes have collection properties for storing child content, we can assemble a tree of objects to fully describe a document. This is called ...