Validation Server Controls->ASP.NET CustomValidator Control

Definition and Usage

The CustomValidator control allows you to write a method to handle the validation of the value entered.

Properties

Property Description
BackColor The background color of the CustomValidator control
ClientValidationFunction Specifies the name of the client-side validation script function to be executed. Note: The script must be in a language that the browser supports, such as VBScript or JScript

With VBScript, the function must be in the form:

Sub FunctionName (source, arguments)

With JScript, the function must be in the form:

Function FunctionName (source, arguments)
ControlToValidate The id of the control to validate
Display The display behavior for the validation control. Legal values are:
  • None (the control is not displayed. Used to show the error message only in the ValidationSummary control)
  • Static (the control displays an error message if validation fails. Space is reserved on the page for the message even if the input passes validation.
  • Dynamic (the control displays an error message if validation fails. Space is not reserved on the page for the message if the input passes validation
EnableClientScript A Boolean value that specifies whether client-side validation is enabled or not
Enabled A Boolean value that specifies whether the validation control is enabled or not
ErrorMessage The text to display in the ValidationSummary control when validation fails. Note: This text will also be displayed in the validation control if the Text property is not set
ForeColor The foreground color of the control
id A unique id for the control
IsValid A Boolean value that indicates whether the control specified by ControlToValidate is determined to be valid
OnServerValidate Specifies the name of the server-side validation script function to be executed
runat Specifies that the control is a server control.  Must be set to "server"
Text The message to display when validation fails

Examples

CustomValidator
ASPX Source:

<script  runat="server">
Sub user(source As object,args As ServerValidateEventArgs)
   if len(args.Value)<8 or len(args.Value)>16 then
    args.IsValid=false
   else
    args.IsValid=true
   end if
End Sub
</script>    

<html>
<body>

<form runat="server">
<asp:Label runat="server" Text="Enter a username: " />
<asp:TextBox id="txt1" runat="server" />
<asp:Button Text="Submit" runat="server"/>
<br />
<asp:Label id="mess" runat="server"/>
<br />
<asp:CustomValidator
ControlToValidate="txt1"
OnServerValidate="user"
Text="A username must be between 8 and 16 characters!"
runat="server"/>
</form>

</body>
</html>

Output Result:
Enter a username:

If you enter your name "shaohai" into the textbox ,it will show:
Enter a username:

A username must be between 8 and 16 characters!

In this example we declare two Label controls, one TextBox control, one Button control, and one CustomValidator control  in an .aspx file. The user() function checks the length of the input value. If the length is <8 or >16 the text "A username must be between 8 and 16 characters!" will appear in the CustomValidator control.

posted on 2007-03-28 16:17  改变热爱  阅读(226)  评论(0)    收藏  举报

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