Why Records Exist?

TL;DR: Records are specialized reference types in C# designed for holding immutable data, with automatic value-based equality and simplified syntax. While they have a tiny performance overhead compared to classes, they insanely reduce boilerplate code and make data handling safer! They’re perfect for DTOs, API responses, and domain events.

What Are Records Really? Let’s Clear the Confusion

Think of records as a drink menu that lists specific cocktails with their ingredients, while classes are like a mixology school that trains you to create endless drink variations. Before going technical, let’s understand what problem records solve:

The old way with classes — look at all this code just to hold some data!


public class PersonClass
{
    public string FirstName { get; init; }
    public string LastName { get; init; }
    
    public PersonClass(string firstName, string lastName)
    {
        FirstName = firstName;
        LastName = lastName;
    }

    // Need to implement equality to compare data
    public override bool Equals(object? obj)
    {
        if (obj is not PersonClass other) return false;
        return FirstName == other.FirstName && 
               LastName == other.LastName;
    }

    // Need this for collections
    public override int GetHashCode()
    {
        return HashCode.Combine(FirstName, LastName);
    }

    // Need this for debugging
    public override string ToString()
    {
        return $"Person {{ FirstName = {FirstName}, LastName = {LastName} }}";
    }
}

The new way with records — same exact functionality!

public record PersonRecord(string FirstName, string LastName);

📝 we will continue with this same class and record example!

Records were introduced because developers spent too much time writing repetitive code just to handle data! just kidding.. Here’s what you get automatically with records:

Immutability

var person = new PersonRecord("John", "Doe");

person.FirstName = "Jane";  // This won't compile:

// Instead, you create a new record with changes:
var updatedPerson = person with { FirstName = "Jane" };  Value-Based Equality (This is Huge!)

Value-Based Equality (This is Huge!)

With classes:

var person1 = new PersonClass("John", "Doe");
var person2 = new PersonClass("John", "Doe");
Console.WriteLine(person1 == person2); // False! Different references

With Records:

var record1 = new PersonRecord("John", "Doe");
var record2 = new PersonRecord("John", "Doe");
Console.WriteLine(record1 == record2); // True! Same data = equal

Easy Copying with Changes

var original = new PersonRecord("John", "Doe");

// Create new record with just FirstName changed:
var updated = original with { FirstName = "Jane" };

but you know what! Records are little or say slightly slow.. lets look into

Why Records Are (Slightly) Slower ??

Records have a small performance overhead compared to classes. but why, and why it usually doesn’t matter:

// Benchmark: Creating 1 million instances
public class PerformanceComparison
{
    private const int Iterations = 1_000_000;

    [Benchmark]
    public void CreateClasses()
    {
        for (int i = 0; i 
{
    public T Data { get; init; }
    public bool Success { get; init; }
    public string? Message { get; init; }
    public DateTime Timestamp { get; init; }

    // Need constructor
    // Need equality
    // Need ToString
    // Need hash code
    // So much boilerplate!
}

With record — done in one line!

public record ApiResponseRecord(T Data, bool Success, string? Message, DateTime Timestamp);

Immutability = Thread Safety

This is thread-safe because records are immutable:

public record Configuration(
    string ApiKey,
    string BaseUrl,
    int Timeout
);

// Can be safely shared between threads
public class Service
{
    private readonly Configuration _config;
    
    public Service(Configuration config)
    {
        _config = config;
    }
    
    // No need for locks - config can't change!
}

Perfect for Domain Events

Records are perfect for events — they’re facts that happened

public record OrderPlaced(
    Guid OrderId,
    string CustomerEmail,
    decimal Amount,
    DateTime PlacedAt
);

public record PaymentReceived(
    Guid OrderId,
    string TransactionId,
    decimal Amount,
    DateTime PaidAt
);

🚩 These are immutable facts — they should never change!

DO or DON’T

1. Deep Record Hierarchies Can Be Slow

❌ DON’T DO THIS:


public record Entity(Guid Id);
public record Person(Guid Id, string Name) : Entity(Id);
public record Employee(Guid Id, string Name, decimal Salary) : Person(Id, Name);
public record Manager(Guid Id, string Name, decimal Salary, string Department) 
    : Employee(Id, Name, Salary);

WHY? Every equality check must traverse the entire hierarchy!

✔️ USE COMPOSITION:

public record Manager(
    Guid Id,
    PersonInfo Person,
    EmployeeInfo Employment,
    string Department
);

2. Be Careful with Collections

❌ PROBLEMATIC:

public record UserList(List Users)
{
    public UserList AddUser(User user) =>
        this with { Users = new List(Users) { user } };
}

This creates a new list EVERY time!

✔️ BETTER:

public class UserCollection
{
    private readonly List _users = new();
    public IReadOnlyList Users => _users.AsReadOnly();
    
    public void AddUser(User user) => _users.Add(user);
}

Lets Check REAL EXAMPLES

1. API Contracts

public record CreateUserRequest(
    string Email,
    string Password,
    string FirstName,
    string LastName
);

public record CreateUserResponse(
    Guid UserId,
    string Email,
    DateTime CreatedAt
);

2. Domain Events

public record OrderShipped(
    Guid OrderId,
    string TrackingNumber,
    DateTime ShippedAt,
    Address ShippingAddress
);

3. Configuration

public record DatabaseConfig(
    string ConnectionString,
    int MaxConnections,
    TimeSpan Timeout,
    bool EnableRetry
);

4. Value Objects in DDD

public record Money(decimal Amount, string Currency)
{
    public static Money Zero(string currency) => new(0, currency);
    
    public Money Add(Money other)
    {
        if (Currency != other.Currency)
            throw new InvalidOperationException("Currency mismatch");
            
        return this with { Amount = Amount + other.Amount };
    }
}

before we close the chapter take a screenshot of this :

Large mutable collections

✅ Use Records For:

DTOs and API contracts
Configuration objects
Domain events
Value objects
Any immutable data structures

❌ Avoid Records For:

Objects that need frequent updates
Deep inheritance hierarchies
Large mutable collections
Complex business logic

so,

Records in C# are not just syntactic sugar — they’re a powerful tool for handling data in a safe, immutable way. While they come with a small performance overhead, the benefits of reduced code, automatic equality, and immutability usually far outweigh the cost!!

Remember:

Records = Immutable data containers
Classes = Mutable objects with behavior
Choose based on your needs, not performance
Watch out for hierarchies and collections

Now you have a complete understanding of when and why to use records in your C# applications!

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| **Use Records For**                      | **Avoid Records For**                    |
|------------------------------------------|------------------------------------------|
| DTOs and API contracts                   | Objects that need frequent updates       |
| Configuration objects                    | Deep inheritance hierarchies             |
| Domain events                            | Large mutable collections                |
| Value objects                            | Complex business logic                   |
| Any immutable data structures            |                                          |

What Are Records Really? Let’s Clear the Confusion