Question

I want to build a C# object from hierarchical XML data usinq LINQ.
I have loaded the XML as an XDocument (by reading the XML from a file into a string first).
I need some guidance on how I should parse this.

Example string read from XML file as

<?xml version="1.0" encoding="utf-8" ?>
<categories version="1.0">
  <category id="0" name="women" description="test">
    <category id="01" name="tops" description="test"></category>
    <category id="02" name="bottoms" description="test"></category>
    <category id="03" name="accessories" description="test"></category>
  </category>
  <category id="1" name="men" description="test">
    <category id="11" name="shirts" description="test"></category>
    <category id="12" name="trousers" description="test"></category>
    <category id="13" name="accessories" description="test"></category>
  </category>
  <category id="2" name="kids &amp; baby" description="test" />
  <category id="3" name="home &amp; living" description="test" />
</categories>

And I have such a POCO class:

[DataContract]
public class Category
{
    [DataMember]
    public int Id { get; set; }

    [DataMember]
    public string Name { get; set; }

    [DataMember]
    public string Description { get; set; }

    [DataMember]
    public List<Category> SubCategories { get; set; }
}

Answer 1

You have two options.

1. Use .NET serialization, in which case you need to specify the XML mappings by decorating your POCO class with appropriate attributes (property name ⇄ XML element name).

2. Use LINQ to XML (like you want do). In that case, the code could look something like this:

   var categories = x.Root.Elements().Select(e =>
       new Category
       {
           Id = int.Parse(e.Attribute("id").Value),
           Name = e.Attribute("name").Value,
           Description = e.Attribute("description").Value,
           SubCategories = e.Elements().Select(e1 =>
               new Category
               {
                   Id = int.Parse(e1.Attribute("id").Value),
                   Name = e1.Attribute("name").Value,
                   Description = e1.Attribute("description").Value
               }).ToList()
       }).ToList();
   

   Or recursively, by adding a recursive method Parse to your class:

   public static Category Parse(XElement value)
   {
       return new Category
       {
           Id = int.Parse(value.Attribute("id").Value),
           Name = value.Attribute("name").Value,
           Description = value.Attribute("description").Value,
           SubCategories = value.Elements().Select(newvalue =>  Parse(newvalue)).ToList()
       };
   }
   

   and calling it like this:

   var categories = x.Root.Elements().Select(e => Category.Parse(e)).ToList();