How do you query XML data in your applications?

2 How to create XML data using LINQ to XML?

One way to create XML data using LINQ to XML is to use the XDocument and XElement classes, which represent an XML document and an XML element, respectively. You can use object initializers and collection initializers to construct XML trees in a declarative way. For example, the following code creates an XML document that contains a list of books:

XDocument doc = new XDocument(
  new XElement("books",
    new XElement("book",
      new XAttribute("id", "1"),
      new XElement("title", "C# in Depth"),
      new XElement("author", "Jon Skeet")
    ),
    new XElement("book",
      new XAttribute("id", "2"),
      new XElement("title", "Pro LINQ"),
      new XElement("author", "Joseph Rattz")
    )
  )
);        

3 How to load XML data using LINQ to XML?

Another way to create XML data using LINQ to XML is to load an existing XML document from a file, a stream, a string, or a URL. You can use the static methods of the XDocument and XElement classes, such as Load, Parse, or LoadFromUri, to load XML data into memory. For example, the following code loads an XML document from a file: XDocument doc = XDocument.Load("books.xml");

4 How to modify XML data using LINQ to XML?

Once you have an XML tree in memory, you can use LINQ to XML to modify its structure or content. You can use methods such as Add, Remove, ReplaceWith, or SetValue to manipulate the nodes of the XML tree. You can also use the XAttribute and XNamespace classes to work with XML attributes and namespaces. For example, the following code adds a new attribute and a new element to the first book element:

XElement firstBook = doc.Root.Elements("book").First();
firstBook.Add(new XAttribute("genre", "programming"));
firstBook.Add(new XElement("publisher", "Manning"));        

5 How to query XML data using LINQ to XML?

The main benefit of using LINQ to XML is that you can query XML data using the same LINQ syntax and operators that you use for other data sources, such as collections, databases, or web services. You can use the standard query operators, such as Where, Select, OrderBy, or GroupBy, to filter, project, sort, or group the XML nodes. You can also use the extension methods of the XElement and XDocument classes, such as Elements, Attributes, Descendants, or Ancestors, to navigate the XML tree. For example, the following code queries the XML document for the titles of the books that have the genre attribute set to "programming":

var titles = from book in doc.Root.Elements("book")
             where (string)book.Attribute("genre") == "programming"
             select (string)book.Element("title");        

6 Here’s what else to consider

This is a space to share examples, stories, or insights that don’t fit into any of the previous sections. What else would you like to add?