What is XML Serialization?

XML Serialisation is broadly similar to Binary Serialization except the file format is XML not Binary, goes without saying. There are a few changes, the references and using references for one. :-

using System.Runtime.Serialization;
using System.Xml.Serialization;
using System.IO;

All classes that are to be serialized must be identified by the attribute [Serializable]. Unlike Binary Serialization, you can not have constructors that take parameters, any attempt at doing so will cause an error.

// For our example, Date Of Birth is a complex class rather than a Date field.
public class clsDOB
{
public int Day;
public int Month;
public int Year;
}
public enum Nationality
{
[XmlEnum(Name="British")]
British,

[XmlEnum(Name = "American")]
American,

[XmlEnum(Name="French")]
France,

[XmlEnum(Name="Australian")]
Australian,

[XmlEnum(Name="German")]
German,

[XmlEnum(Name="Other")]
Other
}

[Serializable, XmlRoot(Namespace = "Human")]
class clsPerson
{

// A parameterless constructor is required whether you have a parameterised one or not.
public clsPerson(string strForename, string strSurname)
{
    this.Forename = strForename;
    this.Surname = strSurname;
    this.DOB = new clsDOB();
}

public clsPerson()
{
    this.DOB = new clsDOB();
}

// This function will not execute, it will compile but won't execute.
[OnDeserialized]
public void DisplayName(System.Runtime.Serialization.StreamingContext context)
{
    Console.WriteLine("Hello {0} {1}", Forename, Surname);
}

[XmlElement]
public string Forename { get; set; }

[XmlAttribute]
public string Surname { get; set; }

// Must be an XML Element so that it can be properly serialized.
[XmlElement]
public clsDOB DOB { get; set; }

[XmlEnum]
Nationality m_CountryofBirth = Nationality.American ;

[XmlElement]
public Nationality CountryOfBirth
{
    get { return m_CountryofBirth; }
    set { m_CountryofBirth = value; } }
}

The methods [OnSerializing], [onDeserialized] etc will not run in an XML serialization. XML Serialization has attributes of its own to determine how data is stored.

Qualifier	Explanation
[XMLAttribute]	The value will be an attribute on the "first" line. Only simple data types can be Attributes, properties that are a class must be elements.
[XMLElement]	The item will be serialised to an XML Element, these can be either simple type or class object types.
[XMLEnum]	Prodives the Element Name for an Enumeration Member of the object.
[XmlRoot]	This names the XML.
[XmlText]	Item will be serialized as XML Text
[XmlType]	Name and namespace of the XML namespace.

Now comes the fun part, the serialization which is really easy. In short, you define the formatter then write the object to a stream. If youlooked at the file that is created, you will find the information is relatively easy to understand.

class Program
{
    static void Main(string[] args)
    {
        //Create Instance of object to be serialized.
        clsPerson Person = new clsPerson();
        Person.Forename = "Mister";
        Person.Surname = "Developer";
        Person.DOB.Day = 25;
        Person.DOB.Month = 1;
        Person.DOB.Year = 2011;

        // Create serializer that will do the work.
        XmlSerializer binFormat = new XmlSerializer(typeof (clsPerson));

        // Open a stream where the serialized file will be stored.
        using (Stream fptr = new FileStream("C:\\temp\\user.dat",
                 FileMode.Create, FileAccess.Write, FileShare.None))
        {
            binFormat.Serialize(fptr, Person);
        }

        Person = null;

        // Deserialize the object.
        using (Stream fptr = File.OpenRead("c:\\temp\\user.dat"))
        {
            // As we have an [OnDeserialized] function,
                 the forename + surname will be displayed on screen.
            Person = (clsPerson)binFormat.Deserialize(fptr);
            Console.WriteLine("Hello {0} {1} who is {2}", Person.Forename,
                Person.Surname, Person.CountryOfBirth.ToString());
        }
        Console.ReadKey();
    }
}

You will be able to read the user.dat file that is created. The above example will create the following xml file.

<?xml version="1.0"?>
<clsPerson xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xmlns:xsd="http://www.w3.org/2001/XMLSchema" Surname="Developer" xmlns="Human">
    <Forename>Mister</Forename>
    <DOB>
        <Day>25</Day>
        <Month>1</Month>
        <Year>2011</Year>
    </DOB>
    <CountryOfBirth>American</CountryOfBirth>
</clsPerson>

Tags - .NET   Serialization   XML

Last Modified : June 2023