MassTransit 8 upgrade– Serialization issues

On one of my projects we are using MassTransit to interact with RabbitMQ. After upgrading to MassTransit 8, we noticed that some of our integration tests started to fail.

Here is the specific message contract that was causing the issue:

	public interface GenerateDocumentsCommand
	{
	Uri TemplateUri { get; }

	IEnumerable<(string FileName,byte[] Data)> Data { get; }
	}

view raw GenerateDocumentsCommand.cs hosted with ❤ by GitHub

Notice the tuple type I’m using in the data contract? That is the culprit of this issue. With the upgrade to MassTransit 8, the default serializer has switched from Newtonsoft.Json to System.Text.Json. And although for most Newtonsoft.Json features an equivalent exists in System.Text.Json, this is not the case for everything.

I solved the issue by switching from a ValueTuple to a record type:

	public interface GenerateDocumentsCommand
	{
	Uri TemplateUri { get; }

	IEnumerable<Document> Data { get; }
	}

	public record Document(string Filename, byte[] Data);