ASP.NET.in.a.Nutshell.Second.Edition [Electronic resources] نسخه متنی

The CustomValidator control allows you to define
your own validation routines. A similar task could be performed by
writing manual validation code in the click event for a submit
button, but using a CustomValidator allows you to
configure client-side validation, create an error message that will
be included in the validation summary, and provide a
"vote" used for the combined
System.Web.UI.Page.IsValid property along with all
other validation controls. A CustomValidator can
also be reused easily to validate multiple controls.

To provide server-side validation, create an event handler for the
ServerValidate event. The string from the input
control and the result of the validation is stored in the provided
ServerValidateEventArgs object. You can also
perform client-side validation, which can improve the responsiveness
of your application by reducing the need for round trips to the
server. However, because client-side validation will not be performed
in some browsers and is easy to circumvent, it should never be used
in place of server validation. To use client-side validation, set the
ClientValidationFunction to the name of a
JavaScript or VBScript function in the .aspx
code portion of your page (not the code-behind class). This script
function should be in a language that the client browser can
understand, which means that JavaScript is the best choice if you are
supporting non-Microsoft browsers. The function must be in the form
function ValidationFunctionName(source,
value), where value is the
value to be validated. This function should return
True or False to indicate
whether the validation succeeded. ASP.NET will take care of the code
necessary to display the corresponding error message. Note that this
is a very bad idea if your function uses
"secret" logic to validate a
password or key, as this logic will be easily retrievable by the
client!

public class 
CustomValidator  : BaseValidator {
// Public Constructors
public 
CustomValidator ( );
// Public Instance Properties
public string 
ClientValidationFunction {set; get; }
// Protected Instance Methods
protected override void 
AddAttributesToRender (System.Web.UI.HtmlTextWriter 
writer ); // overrides BaseValidator
protected override bool 
ControlPropertiesValid ( );             // overrides BaseValidator
protected override bool 
EvaluateIsValid ( );       // overrides BaseValidator
protected virtual bool 
OnServerValidate (string 
value );
// Events
public event ServerValidateEventHandler 
ServerValidate ;
}

Hierarchy

System.Object
System.Web.UI.Control(System.ComponentModel.IComponent,
System.IDisposable,
System.Web.UI.IParserAccessor,
System.Web.UI.IDataBindingsAccessor)

WebControl(System.Web.UI.IAttributeAccessor)
Label
BaseValidator(System.Web.UI.IValidator)
CustomValidator