Introduction and Demonstration
ASP.NET removes the hassle of duplicating validation code, a common problem of
performing data validation using classic ASP, by neatly encapsulating the
standard validations into server controls. You can declaratively relate the
validation control to the control whose value needs to be validated, using the
ControlToValidate attribute. You can also attach multiple validation controls to
a single control. The ASP.NET validation server controls provide server-side
validation for all browsers and supply client-side validation via JavaScript for
browsers that support JavasScript and DHTML. You can also write your own custom
client and/or server-side validation functions, as you'll see in the code
example for this section.
One feature that most web programmers would like to have is a summary of the
validation errors for the values entered into a page's controls. The
ValidationSummary control provides this much-desired feature.
| Control | Purpose |
| CompareValidator | Compares the input in the attached control with a constant value or the property value of another control. |
| CustomValidator | Invokes custom validation code that you have written. |
| RangeValidator | Checks if the value is between specified upper and lower limits. |
| RegularExpressionValidator | Checks if the input matches a pattern defined by a regular expression. |
| RequiredFieldValidator | Ensures that the user can't skip the required value. |
| ValidationSummary | Shows a summary of errors emitted by all validators in that form. |
The simplified syntax
of the validation controls is as follows:
<asp:comparevalidator
id="cvCompare"
controltovalidate="value1"
controltocompare="value2"
operator="equal"
type="integer"
errormessage="Fields are
not equal!" display="dynamic"
runat="server"
/>
<asp:customvalidator
id="cvDate"
controltovalidate="year"
errormessage="Not
a valid year!"
onservervalidate="servervalidation"
clientvalidationfunction="ClientValidate"
display="dynamic"
runat="server"
/>
<asp:rangevalidator
id="rvCompare"
controltovalidate="value"
minimumvalue="0"
maximumvalue="100"
type="integer"
errormessage="Value not
in valid range!" runat="server"
/>
<asp:regularexpressionvalidator
id="reZipCode"
controltovalidate="zipcode"
validationexpression="^\d{5}$|^\d{5}-\d{4}$"
errormessage="Not a
valid Zip code!" display="static"
runat="server"
/>
<asp:requiredfieldvalidator
id="rfvLogin"
controltovalidate="login"
display="static"
errormessage="Login
cannot be blank!" runat="server"
/>
<asp:validationsummary
id="vsSummary"
displaymode="bulletlist"
headertext="Page
has the following errors: "
showsummary="true"
showmessagebox="false"
runat="server"
/>
The controls can then
be referenced programmatically with code fragments like:
cvCompare.ControlToCompare = "Value3"
cvDate.ClientValidationFunction="ClientValidateLeapYear"
reZipCode.ValidationExpression="^\d{5}$|^\d{5}$"
rfvLogin.InitialValue = "SomeUser"
vsSummary.DisplayMode = ValidationSummaryDisplayMode.List
Index.aspx Page
<%@
Page Language="VB"
AutoEventWireup="false"
CodeFile="Default.aspx.vb"
Inherits="_Default"
%>
<!DOCTYPE html PUBLIC "-//W3C//DTD
XHTML 1.0 Transitional//EN""http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html>
<head>
<title>Validation
Control Example</title>
<script
language="javascript">
<!--
function ClientValidate(source, arguments) {
//Declare
variables.
var r,
re;
//Create regular
expression object.
re = new
RegExp(/^[1-9][0-9][0-9][0-9]$/);
//Test for
match.
r = re.test(arguments.Value);
//Return
results.
arguments.IsValid = r;
}
-->
</script>
<script
runat="server">
Sub Page_Load( )
vsSummary.DisplayMode = ValidationSummaryDisplayMode.List
End Sub
Sub ServerValidation (source As object, args _
As ServerValidateEventArgs)
Dim RegExVal As New _
System.Text.RegularExpressions.Regex("^\ d{4}$")
If RegExVal.IsMatch(args.Value) Then
args.IsValid = True
Else
args.IsValid = False
End If
End Sub
</script>
</head>
<body>
<h1>
Validation Control Example</h1>
<form
id="Form1"
runat="server">
<asp:Table
ID="MyTable"
border="1"
CellPadding="5"
CellSpacing="0"
runat="server">
<asp:TableRow
ID="Tablerow1"
runat="server">
<asp:TableCell
ID="Tablecell1"
runat="server">
Compare Validator Control:
<br><br>
Enter two
numbers to compare
</asp:TableCell>
<asp:TableCell
ID="Tablecell2"
runat="server">
<asp:TextBox
ID="value1"
runat="server"
/><br>
<asp:TextBox
ID="value2"
runat="server"
/><br>
<asp:CompareValidator
ID="cvCompare"
ControlToValidate="value1"
ControlToCompare="value2"
Operator="equal"
Type="integer"
ErrorMessage="Fields are not equal!"
Display="dynamic"
runat="server"
/>
</asp:TableCell>
</asp:TableRow>
<asp:TableRow
ID="Tablerow2"
runat="server">
<asp:TableCell
ID="Tablecell3"
runat="server">
CustomValidator Control:
<br><br>
Enter a 4-digit
year
</asp:TableCell>
<asp:TableCell
ID="Tablecell4"
runat="server">
<asp:TextBox
ID="year"
runat="server"
/><br>
<asp:CustomValidator
ID="cvDate"
ControlToValidate="year"
ErrorMessage="Not
a valid year!"
OnServerValidate="servervalidation"
ClientValidationFunction="ClientValidate"
Display="dynamic"
runat="server"
/>
</asp:TableCell>
</asp:TableRow>
<asp:TableRow
ID="Tablerow3"
runat="server">
<asp:TableCell
ID="Tablecell5"
runat="server">
RangeValidator Control:
<br><br>
Enter an
integer between 0 and 100
</asp:TableCell>
<asp:TableCell
ID="Tablecell6"
runat="server">
<asp:TextBox
ID="value"
runat="server"
/><br>
<asp:RangeValidator
ID="rvCompare"
ControlToValidate="value"
MinimumValue="0"
MaximumValue="100"
Type="integer"
ErrorMessage="Value not
in valid range!" runat="server"
/>
</asp:TableCell>
</asp:TableRow>
<asp:TableRow
ID="Tablerow4"
runat="server">
<asp:TableCell
ID="Tablecell7"
runat="server">
RegularExpressionValidator Control:
<br><br>
Enter a valid 5
or 9-digit zip code
</asp:TableCell>
<asp:TableCell
ID="Tablecell8"
runat="server">
<asp:TextBox
ID="zipcode"
runat="server"
/><br>
<asp:RegularExpressionValidator
ID="reZipCode"
ControlToValidate="zipcode"
ValidationExpression="^\d{5}$|^\d{5}-\d{4}$"
ErrorMessage="Not a valid Zip code!"
Display="static"
runat="server"
/>
</asp:TableCell>
</asp:TableRow>
<asp:TableRow
ID="Tablerow5"
runat="server">
<asp:TableCell
ID="Tablecell9"
runat="server">
RequiredFieldValidator Control:
<br><br>
Enter a login
name
</asp:TableCell>
<asp:TableCell
ID="Tablecell10"
runat="server">
<asp:TextBox
ID="login"
runat="server"
/><br>
<asp:RequiredFieldValidator
ID="rfvLogin"
ControlToValidate="login"
Display="static"
ErrorMessage="Login cannot be blank!"
runat="server"
/>
</asp:TableCell>
</asp:TableRow>
<asp:TableRow
ID="Tablerow6"
runat="server">
<asp:TableCell
ID="Tablecell11"
runat="server">
ValidationSummary Control:
</asp:TableCell>
<asp:TableCell
ID="Tablecell12"
runat="server">
<asp:ValidationSummary
ID="vsSummary"
DisplayMode="bulletlist"
HeaderText="Page
has the following errors: "
ShowSummary="true"
ShowMessageBox="false"
runat="server"
/>
</asp:TableCell>
</asp:TableRow>
<asp:TableRow
ID="Tablerow7"
runat="server">
<asp:TableCell
ID="Tablecell13"
colspan="2"
runat="server">
<asp:Button
ID="Button1"
Text="submit"
runat="server"
/>
</asp:TableCell>
</asp:TableRow>
</asp:Table>
<asp:Label
ID="MyLabel"
runat="server"
/>
</form>
</body>
</html>
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