Field Templates - ASP.NET Dynamic Data - page 102

The RegularExpressionValidator is configured by the SetUpRegexValidator method
defined in the code-behind. This method first searches the list of attributes applied to
the column in the data model, Column.Attributes , for a RegularExpressionAttribute
that might have been supplied by the application developer to indicate the expected
phone number pattern. If no such attribute exists, this method creates a default Regular
ExpressionAttribute with the pattern, \(\d{3}\)\d{3}-\d{4} , that matches U.S. phone
numbers, such as [phone], with a three-digit area code in parentheses, followed by a
seven-digit local number. The default attribute also has a generic error message that says
that a column must be a valid phone number.
Having obtained the RegularExpressionAttribute instance, the SetUpRegexValidator
method configures the RegularExpressionValidator control consistently with how the
SetUpValidator method of the FieldTemplateUserControl base class does it—the Text
displayed by the validator itself is always a star symbol; its ErrorMessage is reported
through a ValidationSummary control on the page and the ToolTip contains the complete
error message.
The last step in setting up the RegularExpressionValidator is to call the IgnoreModel
ValidationAttribute method of the FieldTemplateUserControl base class. This allows
the DynamicValidator to ignore the RegularExpressionAttribute during its validation
because this attribute is already covered by the RegularExpressionValidator . Aside from
helping to avoid doing the same validation check twice, this also prevents the regular
expression validation error from being reported twice—first by the RegularExpression
Validator and then by the DynamicValidator control.
Listing 3.13 shows an example of how the new PhoneNumber_Edit field template can be
associated with a column using data annotation attributes.
LISTING 3.13 Associating PhoneNumber Template with a Column
using System.ComponentModel.DataAnnotations;
namespace DataModel
{
[MetadataType(typeof(Employee.Metadata))]
partial class Employee
{
public class Metadata
{
[DataType(DataType.Date)]
public object BirthDate;
[DataType(DataType.Date)]
public object HireDate;
[DataType(DataType.PhoneNumber)]
[RegularExpression(@”\(\d{2,3}\)\d{3}-\d{4}”,
ErrorMessage = “The Home Phone must be a valid phone number.”)]