ASP.NET 2.0 创建一个业务逻辑层 在ASP.NET 2.0中操作数据之二：创建一个业务逻辑层

using System;
using System.Data;
using System.Configuration;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;
using NorthwindTableAdapters;

[System.ComponentModel.DataObject]
public class ProductsBLL
{
 private ProductsTableAdapter _productsAdapter = null;
 protected ProductsTableAdapter Adapter
 {
 get {
  if (_productsAdapter == null)
  _productsAdapter = new ProductsTableAdapter();

  return _productsAdapter; 
 }
 }


 [System.ComponentModel.DataObjectMethodAttribute(System.ComponentModel.DataObjectMethodType.Select, true)]
 public Northwind.ProductsDataTable GetProducts()
 { 
 return Adapter.GetProducts();
 }

 [System.ComponentModel.DataObjectMethodAttribute(System.ComponentModel.DataObjectMethodType.Select, false)]
 public Northwind.ProductsDataTable GetProductByProductID(int productID)
 {
 return Adapter.GetProductByProductID(productID);
 }

 [System.ComponentModel.DataObjectMethodAttribute(System.ComponentModel.DataObjectMethodType.Select, false)]
 public Northwind.ProductsDataTable GetProductsByCategoryID(int categoryID)
 {
 return Adapter.GetProductsByCategoryID(categoryID);
 }

 [System.ComponentModel.DataObjectMethodAttribute(System.ComponentModel.DataObjectMethodType.Select, false)]
 public Northwind.ProductsDataTable GetProductsBySupplierID(int supplierID)
 {
 return Adapter.GetProductsBySupplierID(supplierID);
 }
 [System.ComponentModel.DataObjectMethodAttribute(System.ComponentModel.DataObjectMethodType.Insert, true)]
 public bool AddProduct(string productName, int? supplierID, int? categoryID, string quantityPerUnit, 
    decimal? unitPrice, short? unitsInStock, short? unitsOnOrder, short? reorderLevel, 
    bool discontinued)
 {
 // 新建一个ProductRow实例
 Northwind.ProductsDataTable products = new Northwind.ProductsDataTable();
 Northwind.ProductsRow product = products.NewProductsRow();

 product.ProductName = productName;
 if (supplierID == null) product.SetSupplierIDNull(); else product.SupplierID = supplierID.Value;
 if (categoryID == null) product.SetCategoryIDNull(); else product.CategoryID = categoryID.Value;
 if (quantityPerUnit == null) product.SetQuantityPerUnitNull(); else product.QuantityPerUnit = quantityPerUnit;
 if (unitPrice == null) product.SetUnitPriceNull(); else product.UnitPrice = unitPrice.Value;
 if (unitsInStock == null) product.SetUnitsInStockNull(); else product.UnitsInStock = unitsInStock.Value;
 if (unitsOnOrder == null) product.SetUnitsOnOrderNull(); else product.UnitsOnOrder = unitsOnOrder.Value;
 if (reorderLevel == null) product.SetReorderLevelNull(); else product.ReorderLevel = reorderLevel.Value;
 product.Discontinued = discontinued;

 // 添加新产品
 products.AddProductsRow(product);
 int rowsAffected = Adapter.Update(products);

 // 如果刚好新增了一条记录，则返回true，否则返回false
 return rowsAffected == 1;
 }

 [System.ComponentModel.DataObjectMethodAttribute(System.ComponentModel.DataObjectMethodType.Update, true)]
 public bool UpdateProduct(string productName, int? supplierID, int? categoryID, string quantityPerUnit,
    decimal? unitPrice, short? unitsInStock, short? unitsOnOrder, short? reorderLevel,
    bool discontinued, int productID)
 {
 Northwind.ProductsDataTable products = Adapter.GetProductByProductID(productID);
 if (products.Count == 0)
  // 没有找到匹配的记录，返回false
  return false;

 Northwind.ProductsRow product = products[0];

 product.ProductName = productName;
 if (supplierID == null) product.SetSupplierIDNull(); else product.SupplierID = supplierID.Value;
 if (categoryID == null) product.SetCategoryIDNull(); else product.CategoryID = categoryID.Value;
 if (quantityPerUnit == null) product.SetQuantityPerUnitNull(); else product.QuantityPerUnit = quantityPerUnit;
 if (unitPrice == null) product.SetUnitPriceNull(); else product.UnitPrice = unitPrice.Value;
 if (unitsInStock == null) product.SetUnitsInStockNull(); else product.UnitsInStock = unitsInStock.Value;
 if (unitsOnOrder == null) product.SetUnitsOnOrderNull(); else product.UnitsOnOrder = unitsOnOrder.Value;
 if (reorderLevel == null) product.SetReorderLevelNull(); else product.ReorderLevel = reorderLevel.Value;
 product.Discontinued = discontinued;

 // 更新产品记录
 int rowsAffected = Adapter.Update(product);

 // 如果刚好更新了一条记录，则返回true，否则返回false
 return rowsAffected == 1;
 }

 [System.ComponentModel.DataObjectMethodAttribute(System.ComponentModel.DataObjectMethodType.Delete, true)]
 public bool DeleteProduct(int productID)
 {
 int rowsAffected = Adapter.Delete(productID);

 // 如果刚好删除了一条记录，则返回true，否则返回false
 return rowsAffected == 1;
 }
}

[System.ComponentModel.DataObjectMethodAttribute(System.ComponentModel.DataObjectMethodType.Update, true)]
public bool UpdateSupplierAddress(int supplierID, string address, string city, string country)
{
 Northwind.SuppliersDataTable suppliers = Adapter.GetSupplierBySupplierID(supplierID);
 if (suppliers.Count == 0)
 // 没有找到匹配的项，返回false
 return false;
 else
 {
 Northwind.SuppliersRow supplier = suppliers[0];

 if (address == null) supplier.SetAddressNull(); else supplier.Address = address;
 if (city == null) supplier.SetCityNull(); else supplier.City = city;
 if (country == null) supplier.SetCountryNull(); else supplier.Country = country;

 // 更新供应商的关于地址的信息
 int rowsAffected = Adapter.Update(supplier);

 // 如果刚好更新了一条记录，则返回true，否则返回false
 return rowsAffected == 1;
 }
}

ProductsTableAdapter productsAdapter = new ProductsTableAdapter();
GridView1.DataSource = productsAdapter.GetProducts();
GridView1.DataBind();

ProductsBLL productLogic = new ProductsBLL();
GridView1.DataSource = productLogic.GetProducts();
GridView1.DataBind();

public partial class Northwind
{
 public partial class ProductsDataTable
 {
 public override void BeginInit()
  {
  this.ColumnChanging += ValidateColumn;
  }

  void ValidateColumn(object sender, DataColumnChangeEventArgs e)
  {
  if(e.Column.Equals(this.UnitPriceColumn))
  {
  if(!Convert.IsDBNull(e.ProposedValue) && (decimal)e.ProposedValue < 0)
  {
   throw new ArgumentException("UnitPrice cannot be less than zero", "UnitPrice");
  }
  }
  else if (e.Column.Equals(this.UnitsInStockColumn) ||
   e.Column.Equals(this.UnitsOnOrderColumn) ||
   e.Column.Equals(this.ReorderLevelColumn))
  {
  if (!Convert.IsDBNull(e.ProposedValue) && (short)e.ProposedValue < 0)
  {
   throw new ArgumentException(string.Format("{0} cannot be less than zero", e.Column.ColumnName), e.Column.ColumnName);
  }
  }
  }
 }
}

public bool UpdateProduct(string productName, int? supplierID, int? categoryID, string quantityPerUnit,
    decimal? unitPrice, short? unitsInStock, short? unitsOnOrder, short? reorderLevel,
    bool discontinued, int productID)
{
 Northwind.ProductsDataTable products = Adapter.GetProductByProductID(productID);
 if (products.Count == 0)
  // 没有找到匹配项，返回false
  return false;

 Northwind.ProductsRow product = products[0];

 // 业务规则检查 – 不能停用某供应商所提供的唯一一个产品
 if (discontinued)
 {
  // 获取我们从这个供应商处获得的所有产品
  Northwind.ProductsDataTable productsBySupplier = Adapter.GetProductsBySupplierID(product.SupplierID);

  if (productsBySupplier.Count == 1)
  // 这是我们从这个供应商处获得的唯一一个产品
  throw new ApplicationException("You cannot mark a product as discontinued if its the only product purchased from a supplier");
 }

 product.ProductName = productName;
 if (supplierID == null) product.SetSupplierIDNull(); else product.SupplierID = supplierID.Value;
 if (categoryID == null) product.SetCategoryIDNull(); else product.CategoryID = categoryID.Value;
 if (quantityPerUnit == null) product.SetQuantityPerUnitNull(); else product.QuantityPerUnit = quantityPerUnit;
 if (unitPrice == null) product.SetUnitPriceNull(); else product.UnitPrice = unitPrice.Value;
 if (unitsInStock == null) product.SetUnitsInStockNull(); else product.UnitsInStock = unitsInStock.Value;
 if (unitsOnOrder == null) product.SetUnitsOnOrderNull(); else product.UnitsOnOrder = unitsOnOrder.Value;
 if (reorderLevel == null) product.SetReorderLevelNull(); else product.ReorderLevel = reorderLevel.Value;
 product.Discontinued = discontinued;

 // 更新产品记录
 int rowsAffected = Adapter.Update(product);

 // 如果刚好更新了一条记录，则返回true，否则返回false
 return rowsAffected == 1;
}

ProductsBLL productLogic = new ProductsBLL();

try
{
 // 这个操作将会失败，因为我们试图使用一个小于0的UnitPrice
 productLogic.UpdateProduct("Scott's Tea", 1, 1, null, -14m, 10, null, null, false, 1);
}
catch (ArgumentException ae)
{
 Response.Write("There was a problem: " + ae.Message);
}