Record

Record #

In kotlin, data class is a class used to only hold data, sometimes It’s called a POJO or DTO(Domain Transfer Object).

C# also provides similar feature with record type.

Record type has following characteristics:

  • Immutable
  • Automatic Constructors
  • Automatic Deconstructors
  • Automatic Equals and GetHashCode implementations

Here is the basic example of record type. 

record User(string FirstName, string LastName);

class Program
{
    public static void Main(string[] args)
    {
        var user = new User("John", "Doe");
        var user2 = new User("John", "Doe");
        Console.WriteLine(user.ToString());
        Console.WriteLine(user.GetHashCode());
        Console.WriteLine(user == user2);

        // ERROR!: not allowed to change the value of record type
        // user.FirstName = "David";
    }
}

You can deconstruct the fields of record data to assign them to variables. 

record User(string UserID, string Email);

class Program
{
    public static void Main(string[] args)
    {
        var user = new User("scalalang", "scalalang2@gmail.com");
        var (userID, _) = user;

        // output:
        // userID: scalalang
        Console.WriteLine($"userID: {userID}");
    }
}