using System;

using System.Collections.Generic;

using System.Linq;

using YamlDotNet.Serialization;

using YamlDotNet.Serialization.NamingConventions;

​

public class Book

{

    public string Title { get; set; }

    public List<Author> Authors { get; set; }

}

​

public class Author

{

    public string Name { get; set; }

    public List<Book> Books { get; set; }

}

​

public class Program

{

    public static void Main()

    {

        var knownTypes = new[] { typeof(Author), typeof(Book) };

        SerializerBuilder serializerBuilder = new SerializerBuilder()

            .WithNamingConvention(PascalCaseNamingConvention.Instance)

            .IgnoreFields()

            .EnsureRoundtrip();

        DeserializerBuilder deserializerBuilder = new DeserializerBuilder()

            .WithNamingConvention(PascalCaseNamingConvention.Instance)

            .IgnoreUnmatchedProperties()

            .IgnoreFields();

        foreach (Type type in knownTypes)

        {

            serializerBuilder = serializerBuilder.WithTagMapping($"!{type.FullName}", type);

            deserializerBuilder = deserializerBuilder.WithTagMapping($"!{type.FullName}", type);

        }

        var serializer = serializerBuilder.Build();

        var deserializer = deserializerBuilder.Build();

        List<Book> books1 = new() { new Book() { Title = "title1", Authors = new List<Author>() } };

        Author author1 = new()

        {

            Name = "name1",

            Books = books1

        };

        books1[0].Authors.Add(author1);

        string yaml = serializer.Serialize(author1);

        Console.WriteLine(yaml);

        Author deserialized = deserializer.Deserialize<Author>(yaml);

        Console.WriteLine(deserialized.Name);

        Console.WriteLine(deserialized.Books.FirstOrDefault()?.Title ?? "");

    }

}