Object Serialization in C# (.NET): Complete Guide

Object Serialization in C# (.NET): From Basics to Advanced Techniques

Serialization is the process of converting complex objects (classes, structures) into a format that can be saved to a file, transmitted over a network, or written to a database. The reverse process (restoring an object from a data stream) is called deserialization. In the .NET platform, there are several built-in and third-party tools for serialization, each with its own features, performance characteristics, and areas of application.

In this article, we will cover the main serialization methods in C#: JSON (System.Text.Json and Newtonsoft.Json), XML (XmlSerializer), binary serialization (BinaryFormatter — deprecated but still encountered), and Protocol Buffers (protobuf-net) for high-performance scenarios.

1. JSON Serialization with System.Text.Json

Starting with .NET Core 3.0, Microsoft recommends using the System.Text.Json namespace for working with JSON. It is a fast, low-level, and asynchronous API.

Serialization and deserialization example:

using System;using System.Text.Json;

public class Person{    public string Name { get; set; }    public int Age { get; set; }    public string Email { get; set; }}

class Program{    static void Main()    {        var person = new Person        {            Name = "Ivan Petrov",            Age = 30,            Email = "ivan@example.com"        };

        // Serialize to JSON string        string jsonString = JsonSerializer.Serialize(person);        Console.WriteLine(jsonString);        // Output: {"Name":"Ivan Petrov","Age":30,"Email":"ivan@example.com"}

        // Deserialize from JSON        string jsonInput = @"{""Name"":""Maria"",""Age"":25,""Email"":""maria@test.ru""}";        Person restoredPerson = JsonSerializer.Deserialize<Person>(jsonInput);        Console.WriteLine($"Name: {restoredPerson.Name}, Age: {restoredPerson.Age}");    }}

Serialization configuration:

• Ignoring null properties: JsonSerializerOptions { DefaultIgnoreCondition = JsonIgnoreCondition.WhenWritingNull }
• Pretty printing: JsonSerializerOptions { WriteIndented = true }
• Handling circular references: ReferenceHandler.Preserve

2. Newtonsoft.Json (Json.NET) — The Classic

Before System.Text.Json, the de facto standard was the Newtonsoft.Json library (installed via NuGet). It supports more scenarios: dynamic objects, attributes, converters, and flexible settings.

using Newtonsoft.Json;

public class Order{    public int Id { get; set; }    public decimal Amount { get; set; }    [JsonIgnore]    public string InternalNote { get; set; } // This field will not be serialized}

var order = new Order { Id = 1, Amount = 99.99m, InternalNote = "Secret" };string json = JsonConvert.SerializeObject(order, Formatting.Indented);Console.WriteLine(json);// {//   "Id": 1,//   "Amount": 99.99// }

var deserialized = JsonConvert.DeserializeObject<Order>(json);

3. XML Serialization (XmlSerializer)

For the XML format, .NET uses the XmlSerializer class. It is well-suited for compatibility with legacy systems and SOAP services.

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

[Serializable]public class Product{    [XmlAttribute]    public int Id { get; set; }    [XmlElement("ProductName")]    public string Name { get; set; }}

class Program{    static void Main()    {        var product = new Product { Id = 42, Name = "Laptop" };

        // Serialize