MassTransit–Use record types for your message contracts

So far I always used an interface for my message contracts:

	public interface UserRegistered{
	Guid UserId{get;}
	}

view raw UserRegistered.cs hosted with ❤ by GitHub

In combination with anonymous types, you don’t even need to implement this interface yourself but create an anonymous type on the fly that will be published:

bus.Publish<UserRegistered>(new { UserId = Guid.NewGuid() });

view raw PublishInterface.cs hosted with ❤ by GitHub

Let’s see if we can do the same thing by using a record type instead. Here is our rewritten message contract:

	public record UserRegistered{
	public Guid UserId { get; init; }
	}

view raw UserRegistered.cs hosted with ❤ by GitHub

We could publish the message in the same way as before:

bus.Publish<UserRegistered>(new { UserId = Guid.NewGuid() });

view raw PublishInterface.cs hosted with ❤ by GitHub

BUT you can also take advantage of the "target-typing" feature in C# 9, this allows us to create a specific instance of the record type instead of an anonymous type:

bus.Publish<UserRegistered>(new() { UserId=Guid.NewGuid() });

view raw PublishRecordType.cs hosted with ❤ by GitHub

Did you notice the difference? We call the constructor of the record type through the 'new ()' syntax.