Relationships

public sealed class User : AggregateRoot
{
    public string Name { get; private set; }
    public string Email { get; private set; }
 
    // Navigation property (one-to-many)
    private readonly List<Post> _posts = new();
    public IReadOnlyCollection<Post> Posts => _posts.AsReadOnly();
 
    public Result<Post> AddPost(string title, string content)
    {
        var post = Post.Create(title, content, this);
        if (post.IsFailure) return post;
 
        _posts.Add(post.Value);
        return post;
    }
}

public sealed class Post : Entity
{
    public string Title { get; private set; }
    public string Content { get; private set; }
 
    // Foreign key
    public Guid AuthorId { get; private set; }
 
    // Navigation property (back-reference)
    public User Author { get; private set; }
 
    internal static Result<Post> Create(string title, string content, User author)
    {
        // Validation...
        return Result.Ok(new Post
        {
            Title = title,
            Content = content,
            Author = author,
            AuthorId = author.Id
        });
    }
}

public class PostConfiguration : IEntityTypeConfiguration<Post>
{
    public void Configure(EntityTypeBuilder<Post> builder)
    {
        builder.ToTable("posts");
 
        builder.HasKey(e => e.Id);
 
        builder.Property(e => e.Title)
            .IsRequired()
            .HasMaxLength(200);
 
        builder.Property(e => e.Content)
            .IsRequired();
 
        // Relationship configuration
        builder.HasOne(p => p.Author)
            .WithMany(u => u.Posts)
            .HasForeignKey(p => p.AuthorId)
            .OnDelete(DeleteBehavior.Cascade);
    }
}