JsonSerializer basics

Learn to convert objects to JSON with JsonSerializer.

What is serialization?

Serialization turns an object into text so it can be saved to a file or sent over a network. In C# the JsonSerializer class from the System.Text.Json namespace does this job.

Call: string text = JsonSerializer.Serialize(obj);. The return value is a string; the object's properties are written as key-value pairs. For example new Person { Name = "Alex", Age = 30 } produces {"Name":"Alex","Age":30}. The reverse operation is Deserialize.

The System.Text.Json namespace

To use JsonSerializer, add using System.Text.Json; at the top. This namespace is .NET's built-in serializer; no external package is needed.

A class is serializable by default: public properties are processed automatically. A property like public string Name { get; set; } becomes the pair "Name":"value". private members are not serialized.

Exercise Serialize a Person object

The Person class below is ready. In Main create a Person instance (Name = "Alex", Age = 30), convert it to text with JsonSerializer.Serialize and print with Console.WriteLine.

Show example solution

Create the instance with var p = new Person { Name = "Alex", Age = 30 };, convert with string text = JsonSerializer.Serialize(p);, print with Console.WriteLine(text);.
Example solution:
using System;
using System.Text.Json;

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

class Program
{
    static void Main()
    {
        var p = new Person { Name = "Alex", Age = 30 };
        string text = JsonSerializer.Serialize(p);
        Console.WriteLine(text);
    }
}

Test yourself

What does Serialize return?
```
JsonSerializer.Serialize(p)
```
- string
- Person
- byte[]
- void
Show answer

string — Correct. Serialize returns the text representation of the object as a string.

Complete the Serialize call

string text = JsonSerializer.____(p);

Show answer

string text = JsonSerializer.Serialize(p);

Match each method to its role

Serialize

Object to text
Deserialize

Text to object
JsonSerializer

Class name
System.Text.Json

Namespace

Next lesson: Deserialize

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