LINQ to XML

Content:
1. Loading simple elements
2. Loading elements with nested elements
3. Loading elements deep in hierarchy
4. Reading simple list

---

Linq to XML allows querying XML data without using xPath. Overview on hookedonlinq.com

Assuming input data like below

XML
<?xml version="1.0" encoding="utf-8" ?>
<persons>
  
  <person id="1">
    <name>John</name>
    <children>
      <child>
        <name>Peter</name>
        <age>10</age>
      </child>
    </children>
  </person>

  <person id="2">
    <name>Paul</name>
    <children>
      <child>
        <name>Max</name>
        <age>12</age>
      </child>
    </children>
  </person>
  
</persons>

that can be represented by classes

C#
public class Person
{
    public int Id;
    public string Name;
    public List<Child> Children;
}

public class Child
{
    public string Name;
    public int Age;
}

You need to include System.Xml.Linq namespace.

C#
XDocument data = XDocument.Load("persons.xml");

// select persons
List<Person> people = (
                        from p in data.Descendants("person")
                        where (int)p.Attribute("id") < 3
                        orderby (string)p.Element("name")
                        select new Person()
                        {
                            Id = (int)p.Attribute("id"),
                            Name = (string)p.Element("name"),
                        }
                      ).ToList();

C#
// select persons with children (nested elements)
List<Person> people1 = (
                        from p in data.Descendants("person")
                        select new Person()
                        {
                            Id = (int)p.Attribute("id").Value,
                            Name = (string)p.Element("name"),
                            Children = (
                                        from ch in p.Descendants("child")
                                        select new Child()
                                        {
                                            Name = (string)ch.Element("name"),
                                            Age = (int)ch.Element("age")
                                        }
                                    ).ToList()
                        }
                      ).ToList();

C#
// select nested elements only - children
List<Child> children =    (from ch in config.Descendants("child")
                           where (string)ch.Parent.Parent.Element("name") == "John"
                           select new Child
                           {
                               Name = (string)ch.Element("name"),
                               Age = (int)ch.Element("age")
                           }
                          ).ToList();

Items can be read from a simple list

XML
<items>
  <item>1</item>
  <item>2</item>
<items>

C#
List<string> result = (from i in data.Descendants("item")
					   select i.Value)
					   .ToList();