public class CategoryMap : ClassMap<Category>
    {
        public CategoryMap()
        {
            Id(x => x.Id).GeneratedBy.Identity();
            Map(x => x.Name);
        }
    }

    public class CommentMap : ClassMap<Comment>
    {
        public CommentMap()
        {
            Id(x => x.Id).GeneratedBy.Identity();
            Map(x => x.Content);

            References(x => x.Commenter)
                .Column("UserId");

            References(x => x.Post)
                .Column("PostId");
        }
    }

    public class PostMap : ClassMap<Post>
    {
        public PostMap()
        {
            Id(x => x.Id).GeneratedBy.Identity();
            Map(x => x.Title);
            Map(x => x.Content);
            Map(x => x.PublishedAt);

            References(x => x.Author)
                .Column("UserId");

            HasManyToMany(x => x.Tags)
                .Table("PostTags")
                .ParentKeyColumn("PostId")
                .ChildKeyColumn("TagId");

            HasManyToMany(x => x.Categories)
                .Table("PostCategories")
                .ParentKeyColumn("PostId")
                .ChildKeyColumn("CategoryId");

            HasMany(x => x.Comments)
                .KeyColumn("PostId")
                .Inverse();
        }
    }

    public class TagMap : ClassMap<Tag>
    {
        public TagMap()
        {
            Id(x => x.Id).GeneratedBy.Identity();
            Map(x => x.Name);
        }
    }

    public class UserMap : ClassMap<User>
    {
        public UserMap()
        {
            Id(x => x.Id).GeneratedBy.Identity();
            Map(x => x.Email);
            Map(x => x.DisplayName);
            Map(x => x.FirstName);
            Map(x => x.Surname);
            Map(x => x.Password);
        }
    }