Xml Serialization And Deserialization In C# Complete Guide

Example 1: Serializing a Simple Class

Let's start with a basic class that represents a person:

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

// Step 1: Define the class to serialize
[XmlRoot("Person")]
public class Person
{
    [XmlElement("FirstName")]
    public string FirstName { get; set; }

    [XmlElement("LastName")]
    public string LastName { get; set; }

    [XmlElement("Age")]
    public int Age { get; set; }

    // Default constructor is required by XmlSerializer
    public Person() 
    {
        // Initialization can be done here if necessary
    }
    
    public Person(string firstName, string lastName, int age)
    {
        this.FirstName = firstName;
        this.LastName = lastName;
        this.Age = age;
    }
}

class Program
{
    static void Main()
    {
        // Step 2: Create an instance of the class
        Person person = new Person("John", "Doe", 30);

        // Step 3: Serialize the object to XML
        XmlSerializer serializer = new XmlSerializer(typeof(Person));

        using (StreamWriter writer = new StreamWriter("person.xml"))
        {
            serializer.Serialize(writer, person);
        }
        
        Console.WriteLine("Serialization completed. Check 'person.xml' for the output.");
    }
}

Explanation:

1. Define the Class: The Person class is defined with properties FirstName, LastName, and Age. The [XmlRoot] attribute specifies the root element name for the XML, and the [XmlElement] attributes specify the names of elements for each property.
2. Create an Instance: We create an instance of the Person class.
3. Serialize: Using the XmlSerializer, we serialize the Person object to an XML file named person.xml.

Example 2: Deserializing the XML Back to an Object

Now that we have our XML file, let's deserialize it back into a Person object:

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

// Same class definition as above
[XmlRoot("Person")]
public class Person
{
    [XmlElement("FirstName")]
    public string FirstName { get; set; }

    [XmlElement("LastName")]
    public string LastName { get; set; }

    [XmlElement("Age")]
    public int Age { get; set; }

    public Person() 
    {
        // Default constructor
    }
    
    public Person(string firstName, string lastName, int age)
    {
        this.FirstName = firstName;
        this.LastName = lastName;
        this.Age = age;
    }
}

class Program
{
    static void Main(string[] args)
    {
        // Step 1: Deserialize the XML back to an object
        XmlSerializer serializer = new XmlSerializer(typeof(Person));
        
        using (StreamReader reader = new StreamReader("person.xml"))
        {
            Person personBack = (Person)serializer.Deserialize(reader);
            
            // Step 2: Use the deserialized object
            Console.WriteLine($"Deserialized Person:");
            Console.WriteLine($"Name: {personBack.FirstName} {personBack.LastName}");
            Console.WriteLine($"Age: {personBack.Age}");
        }
    }
}

Explanation:

1. Deserialize: We use the XmlSerializer again, but this time we call the Deserialize method to read the XML file person.xml and convert it back to a Person object.
2. Output: We print the properties of the deserialized Person object.

Example 3: Serializing and Deserializing a Collection

Next, let's consider a scenario where we want to serialize and deserialize a collection of Person objects.

using System;
using System.Collections.Generic;
using System.Xml.Serialization;
using System.IO;

// Same class definition as above
[XmlRoot("Person")]
public class Person
{
    [XmlElement("FirstName")]
    public string FirstName { get; set; }

    [XmlElement("LastName")]
    public string LastName { get; set; }

    [XmlElement("Age")]
    public int Age { get; set; }

    public Person() 
    {
        // Default constructor
    }

    public Person(string firstName, string lastName, int age)
    {
        this.FirstName = firstName;
        this.LastName = lastName;
        this.Age = age;
    }
}

[XmlRoot("People")]
public class PeopleList
{
    [XmlElement("Person")]
    public List<Person> People { get; set; } = new List<Person>();

    // Default constructor is required by XmlSerializer
    public PeopleList() {}

    public void AddPerson(Person person)
    {
        this.People.Add(person);
    }
}

class Program
{
    static void Main(string[] args)
    {
        // Step 1: Create a list of people
        PeopleList peopleList = new PeopleList();
        peopleList.AddPerson(new Person("Alice", "Smith", 25));
        peopleList.AddPerson(new Person("Bob", "Brown", 40));

        // Step 2: Serialize the list to XML
        XmlSerializer serializer = new XmlSerializer(typeof(PeopleList));

        using (StreamWriter writer = new StreamWriter("peoplelist.xml"))
        {
            serializer.Serialize(writer, peopleList);
        }

        Console.WriteLine("Serialization completed. Check 'peoplelist.xml' for the output.");

        // Step 3: Deserialize the XML back to a list of people
        XmlSerializer deserializeSerializer = new XmlSerializer(typeof(PeopleList));
        
        using (StreamReader reader = new StreamReader("peoplelist.xml"))
        {
            PeopleList peopleBack = (PeopleList)deserializeSerializer.Deserialize(reader);

            // Step 4: Use the deserialized list
            Console.WriteLine("\nDeserialized People List:");
            foreach (Person p in peopleBack.People)
            {
                Console.WriteLine($"Name: {p.FirstName} {p.LastName}, Age: {p.Age}");
            }
        }
    }
}

Explanation:

1. Collection Class: PeopleList contains a list of Person objects. The [XmlRoot] attribute for PeopleList specifies the root of the XML. The [XmlElement] attribute inside PeopleList specifies the name of the elements containing persons.
2. Serialize: Serializes the PeopleList object to an XML file named peoplelist.xml.
3. Deserialize: Reads the XML file and converts it back to a PeopleList object.
4. Output: Iterate through and print the properties of each Person in the deserialized list.

These examples are meant to give a clear understanding of how XML serialization and deserialization work in C#. As your requirements grow, you might find it necessary to explore more advanced usage such as custom attributes, namespaces, etc., but this should form a strong starting point.