Fluent NHibernate Mapping and Retrieve Hierarchy Table - fluent-nhibernate

Question

I have a hierarchy category table like this
Id int,
Description varchar(100),
ParentId int,
Ordinal int,
IsActive bit
I want to fetch all of the Categories from parent to child, so when I called session.get<Category>(id), it already fetched all of their children. Here is my map and class:
class Category
{
public virtual int Id {get; set;}
public virtual string Description {get; set;}
public virtual int ParentId {get; set;}
public virtual int Ordinal {get; set;}
public virtual bool IsActive {get; set;}
}
class CategoryMap : ClassMap<Category>
{
public CategoryMap()
{
Table("TB_CATEGORY");
Id(f => f.Id).GeneratedBy.Native();
Map(f => f.Description);
Map(f => f.ParentId);
Map(f => f.Ordinal);
Map(f => f.IsActive);
}
}
I've searched so many articles, and am still confused when using their solutions because they don't tell me about the table structure and the mappings. Like this one from ayende blog, I think its a good solution, but I can't follow it well enough to apply this in my project.
Could somebody give me a step by step tutorial to achieve this? Are my mapping and class correct?

Answer 1

using the following classes
class Category
{
public virtual int Id {get; private set;}
public virtual string Description {get; set;}
public virtual Category Parent {get; set;}
public virtual bool IsActive {get; set;}
public virtual IList<Category> Children {get; private set;}
public override bool Euqals(object obj)
{
var other = obj as Category;
return other != null && (Id == 0) ? ReferenceEquals(other, this) : other.Id == Id;
}
public override int GetHashCode()
{
return Id;
}
}
class CategoryMap : ClassMap<Category>
{
public CategoryMap()
{
Table("TB_CATEGORY");
Id(f => f.Id).GeneratedBy.Native();
Map(f => f.Description);
References(f => f.Parent).Column("ParentId");
HasMany(f => f.Children)
.AsList(i => i.Column("Ordinal")) // let the list have the correct order of child items
.KeyColumn("ParentId")
.Inverse(); // let the reference maintain the association
Map(f => f.IsActive);
}
}
then you can query
var categoriesWithChildrenInitialised = session.QueryOver<Category>()
.Fetch(c => c.Children).Eager
.List()