ASP .NET 不同阶段的数据验证判断和提示
在WEB进行数据验证和提示还是有些麻烦。
1：在页面录入控件中，可以使用验证控件
2：在DAL中（参照http://www.asp.net/learn/dataaccess/tutorial18cs.aspx?tabid=63）
protected void GridView1_RowUpdated(object sender, GridViewUpdatedEventArgs e)
{
if (e.Exception != null)
{
// Display a user-friendly message
ExceptionDetails.Visible = true;
ExceptionDetails.Text = "There was a problem updating the product. ";
if (e.Exception.InnerException != null)
{
Exception inner = e.Exception.InnerException;
if (inner is System.Data.Common.DbException)
ExceptionDetails.Text += "Our database is currently experiencing problems. Please try again later.";
else if (inner is NoNullAllowedException)
ExceptionDetails.Text += "There are one or more required fields that are missing.";
else if (inner is ArgumentException)
{
string paramName = ((ArgumentException)inner).ParamName;
ExceptionDetails.Text += string.Concat("The ", paramName, " value is illegal.");
}
else if (inner is ApplicationException)ExceptionDetails.Text += inner.Message;
}
// Indicate that the exception has been handled
e.ExceptionHandled = true;
// Keep the row in edit mode
e.KeepInEditMode = true;
}
}

3：在BLL中
public bool UpdateProduct(string productName, decimal? unitPrice, short? unitsInStock, int productID)
{
Northwind.ProductsDataTable products = Adapter.GetProductByProductID(productID);
if (products.Count == 0)
// no matching record found, return false
return false;
Northwind.ProductsRow product = products[0];
// Make sure the price has not more than doubled
if (unitPrice != null && !product.IsUnitPriceNull())
if (unitPrice > product.UnitPrice * 2)
throw new ApplicationException("When updating a product price," + " the new price cannot exceed twice the original price.");
product.ProductName = productName;
if (unitPrice == null) product.SetUnitPriceNull();
else product.UnitPrice = unitPrice.Value;
if (unitsInStock == null) product.SetUnitsInStockNull();
else product.UnitsInStock = unitsInStock.Value;
// Update the product record
int rowsAffected = Adapter.Update(product);
// Return true if precisely one row was updated, otherwise false
return rowsAffected == 1;
}