How to Serialize and Deserialize JSON in C#

JSON serialization and deserialization in C# has become remarkably straightforward with the System.Text.Json namespace, introduced in .NET Core 3.0 as a modern alternative to Newtonsoft.Json.

The JsonSerializer class provides static methods to convert objects to JSON strings (Serialize) and parse JSON strings back into objects (Deserialize).

For basic serialization, you can simply call JsonSerializer.Serialize(object) on any object, and it will automatically convert public properties into their JSON representation.

Similarly, JsonSerializer.Deserialize<T>(jsonString) converts JSON back into strongly-typed objects. The process becomes even more powerful when combined with custom attributes like [JsonPropertyName] to control property naming and [JsonIgnore] to exclude specific properties from serialization.

When working with more complex scenarios, you can customize the serialization process using JsonSerializerOptions.

This allows you to control various aspects such as case sensitivity, indentation, handling of null values, and custom converters. For example, setting PropertyNameCaseInsensitive = true enables case-insensitive property matching during deserialization, while WriteIndented = true produces formatted JSON output.

It's also worth noting that System.Text.Json is designed with performance in mind, offering better performance compared to Newtonsoft.Json for most scenarios.

Example

// Define a class to serialize
public class Person
{
    public string Name { get; set; }
    [JsonPropertyName("birth_date")]
    public DateTime BirthDate { get; set; }
    [JsonIgnore]
    public int InternalId { get; set; }
}

// Serialization example
Person person = new Person 
{ 
    Name = "John Doe", 
    BirthDate = new DateTime(1990, 1, 1) 
};
string json = JsonSerializer.Serialize(person);

// Deserialization example
Person deserializedPerson = JsonSerializer.Deserialize<Person>(json);

// Using JsonSerializerOptions
var options = new JsonSerializerOptions
{
    WriteIndented = true,
    PropertyNameCaseInsensitive = true,
    PropertyNamingPolicy = JsonNamingPolicy.CamelCase
};
string prettyJson = JsonSerializer.Serialize(person, options);

// Working with collections
List<Person> people = new List<Person> { person };
string jsonArray = JsonSerializer.Serialize(people);
List<Person> deserializedPeople = JsonSerializer.Deserialize<List<Person>>(jsonArray);
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Related

Storing passwords as plain text is dangerous. Instead, you should hash them using a strong, slow hashing algorithm like BCrypt, which includes built-in salting and resistance to brute-force attacks.

Step 1: Install BCrypt NuGet Package

Before using BCrypt, install the BCrypt.Net-Next package:

dotnet add package BCrypt.Net-Next

or via NuGet Package Manager:

Install-Package BCrypt.Net-Next

Step 2: Hash a Password

Use BCrypt.HashPassword() to securely hash a password before storing it:

using BCrypt.Net;

string password = "mySecurePassword123";
string hashedPassword = BCrypt.HashPassword(password);

Console.WriteLine(hashedPassword); // Output: $2a$12$...

Step 3: Verify a Password

To check a user's login attempt, use BCrypt.Verify():

bool isMatch = BCrypt.Verify("mySecurePassword123", hashedPassword);
Console.WriteLine(isMatch); // Output: True

Ensuring proper hashing should be at the top of your list when it comes to building authentication systems.

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Raw string literals in C# provide a flexible way to work with multiline strings, with some interesting rules around how quotes work.

The key insight is that you can use any number of double quotes (three or more) to delimit your string, as long as the opening and closing sequences have the same number of quotes.

The Basic Rules

  1. You must use at least three double quotes (""") to start and end a raw string literal
  2. The opening and closing quotes must have the same count
  3. The closing quotes must be on their own line for proper indentation
  4. If your string content contains a sequence of double quotes, you need to use more quotes in your delimiter than the longest sequence in your content

Examples with Different Quote Counts

// Three quotes - most common usage
string basic = """
    This is a basic
    multiline string
    """;

// Four quotes - when your content has three quotes
string withThreeQuotes = """"
    Here's some text with """quoted""" content
    """";

// Five quotes - when your content has four quotes
string withFourQuotes = """""
    Here's text with """"nested"""" quotes
    """"";

// Six quotes - for even more complex scenarios
string withFiveQuotes = """"""
    Look at these """""nested""""" quotes!
    """""";

The N+1 Rule

The general rule is that if your string content contains N consecutive double quotes, you need to wrap the entire string with at least N+1 quotes. This ensures the compiler can properly distinguish between your content and the string's delimiters.

// Example demonstrating the N+1 rule
string example1 = """
    No quotes inside
    """; // 3 quotes is fine

string example2 = """"
    Contains """three quotes"""
    """"; // Needs 4 quotes (3+1)

string example3 = """""
    Has """"four quotes""""
    """""; // Needs 5 quotes (4+1)

Practical Tips

  • Start with three quotes (""") as your default
  • Only increase the quote count when you actually need to embed quote sequences in your content
  • The closing quotes must be on their own line and should line up with the indentation you want
  • Any whitespace to the left of the closing quotes defines the baseline indentation
// Indentation example
string properlyIndented = """
    {
        "property": "value",
        "nested": {
            "deeper": "content"
        }
    }
    """; // This line's position determines the indentation

This flexibility with quote counts makes raw string literals extremely versatile, especially when dealing with content that itself contains quotes, like JSON, XML, or other structured text formats.

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In C#, you can format an integer with commas (thousands separator) using ToString with a format specifier.

int number = 1234567;
string formattedNumber = number.ToString("N0"); // "1,234,567"
Console.WriteLine(formattedNumber);

Explanation:

"N0": The "N" format specifier stands for Number, and "0" means no decimal places. The output depends on the culture settings, so in regions where , is the decimal separator, you might get 1.234.567.

Alternative:

You can also specify culture explicitly if you need a specific format:

using System.Globalization;

int number = 1234567;
string formattedNumber = number.ToString("N0", CultureInfo.InvariantCulture);
Console.WriteLine(formattedNumber); // "1,234,567"
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