Optimizing Performance in NHibernate: Part 2: A Collection of Enhancements

using System;
using System.Collections;

namespace Northwind.Domain.Entities
{
	/// <summary>
	/// Product object for NHibernate mapped table 'Products'.
	/// </summary>
    public class Product : EntityBase
	{
		#region Member Variables
		
		protected int _id;
		protected string _productName;
		protected string _quantityPerUnit;
		protected decimal _unitPrice;
		protected short _unitsInStock;
		protected short _unitsOnOrder;
		protected short _reorderLevel;
		protected bool _discontinued;
	    protected OrderDetail _orderDetail;
		
	    
	    protected Category _category = null;
		protected Supplier _supplier = null;
		
        protected int categoryID = 0;
        protected int supplierID = 0;

		#endregion

		#region Constructors

		public Product() { }

		public Product( string productName, string quantityPerUnit, decimal unitPrice, short unitsInStock, short unitsOnOrder, short reorderLevel, bool discontinued, Category category, Supplier supplier )
		{
			this._productName = productName;
			this._quantityPerUnit = quantityPerUnit;
			this._unitPrice = unitPrice;
			this._unitsInStock = unitsInStock;
			this._unitsOnOrder = unitsOnOrder;
			this._reorderLevel = reorderLevel;
			this._discontinued = discontinued;
			this._category = category;
			this._supplier = supplier;
		}

		#endregion

		#region Public Properties

		public int Id
		{
			get {return _id;}
			set {_id = value;}
		}

		public string ProductName
		{
			get { return _productName; }
			set
			{
				if(value != _productName) IsModified = true;
				_productName = value;
			}
		}

		public string QuantityPerUnit
		{
			get { return _quantityPerUnit; }
			set
			{
				if(value != _quantityPerUnit) IsModified = true;
				_quantityPerUnit = value;
			}
		}

		public decimal UnitPrice
		{
			get { return _unitPrice; }
			set { _unitPrice = value; }
		}

		public short UnitsInStock
		{
			get { return _unitsInStock; }
			set { _unitsInStock = value; }
		}

		public short UnitsOnOrder
		{
			get { return _unitsOnOrder; }
			set { _unitsOnOrder = value; }
		}

		public short ReorderLevel
		{
			get { return _reorderLevel; }
			set { _reorderLevel = value; }
		}

		public bool Discontinued
		{
			get { return _discontinued; }
			set { _discontinued = value; }
		}
	    
	    private int CategoryID
	    {
	        get{return categoryID;}
	        set{ categoryID = value;}
	    }
        private int SupplierID
        {
            get { return supplierID; }
            set { supplierID = value; }
        }
		public Category Category
		{
			get
			{
			    if(_category==null)
			    {
			        Repository r = new Repository();
                    r.Open();
                    Category category =(Category) r.Get(typeof (Category), categoryID);
                    _category = category;
			    }
			    return _category;
			}
			set { 
			    _category = value;
                categoryID = value.Id;
			}
		}
		public Supplier Supplier
		{
            get
            {
                if (_supplier == null)
                {
                    Repository r = new Repository();
                    r.Open();
                    Supplier supplier = (Supplier)r.Get(typeof(Supplier), supplierID);
                    _supplier = supplier;
                }
                return _supplier;
            }
			set { 
			    _supplier = value;
                supplierID = value.Id;
			}
		}

		public OrderDetail OrderDetail
		{
			get { return _orderDetail; }
			set { _orderDetail = value; }
		}

		#endregion
	}
}