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id="rvTickets"

controltovalidate="Tickets"

minimumvalue=1

maximumvalue=4

type="Integer"

display="dynamic"

errormessage="You can only purchase 1 to 4 tickets, please try again."

runat="Server">

</asp:rangevalidator><br>

Launch your browser and navigate to Range.aspx. A screen similar to Figure 6-8 is displayed.

Figure 6-8: Range validator control example 1

As you can see from the code fragment, the MinimumValue property is set to 1 and the MaximumValue property is set to 4. Now, enter a value less than 1 or greater than 8 in the Number of tickets field and then press the Tab key. A screen similar to Figure 6-9 should be displayed.

Figure 6-9: Range validator control example 2

Because you specified a range of 1 to 8, any other value will fail validation and your error message will be displayed. Enter a value within the range and then click Validate. A screen similar to Figure 6-10 is displayed.

Figure 6-10: Range validator control example 3

MinimumControl and MaximumControl properties

As mentioned in the previous section, the RangeValidator control is useful when you need to make sure that a value falls within a specified range of values. You can specify values for the MinimumControl and MaximumControl properties for the range just as easily as you did for the MinimumValue and MaximumValue properties previously. Try it! Add two controls to the form and then set the MaximumControl and MinimumControl properties to these new controls. Make sure that you remove the

MinimumValue and MaximumValue properties.

Using the RegularExpressionValidator Control

Use the RegularExpressionValidator control to check a value against a regular expression. It checks whether the value of the associated input control matches the

Figure 6-11: Regular expression validator control example 1

Because the format in your ValidationExpression is xxx xxx-xxxx, enter some other phone sequence to test the validation control. After you enter the value, press the Tab key, and Figure 6-12 displays.

Figure 6-12: Regular expression validator control example 2

Because the phone number is not in the expected format, validation fails and your error message is displayed. This time, enter the correct phone number format and then click the Validate button. The validation message is cleared from the page and your message is displayed. Your screen should look like Figure 6-13.

<asp:customvalidator

id="cvCardNumber"

controltovalidate="CardNumber"

ClientValidationFunction="IsCardValid"

display="dynamic"

errormessage="Invalid credit card number, please try again."

runat="Server">

</asp:customvalidator><br>

By now, you should be familiar with most of the properties when wiring up the validation controls. However, for the CustomValidator control, you are interested in the

ClientValidationFunction or the OnServerValidate event. In the example, you are going to concentrate on the ClientValidationFunction event. Here, this property points to the IsCardValid function, which must be a valid function defined as JScript or VBScript on the client. Take a look at the code for this function:

<script language="javascript">

//--- source is the name of control that is being checked

//--- value is actual value that is entered into the control

function IsCardValid(source, value) {

if (value != "5555555555555555" )

return false;

else

return true;

}

</script>

The ClientValidationFunction event expects two parameters:

§source: The name of the control that is being validated, pointed to by the ControlToValidate property

§value: The actual value entered by the user

Keep in mind that you can use whatever name you prefer; you don't need to use source and value. The ClientValidationFunction event must return a True or False condition to indicate whether validation succeeded for failed.

Run the example by launching your browser and navigating to Custom.aspx, shown in Figure 6-14.

Figure 6-14: Custom validator control example 1

For this example, the IsCardValid function expects the credit card number to be a string of all 5s. In a real-world application, you might want to add the logic to validate the credit card so that you can make sure an individual's credit card number is valid.

Enter a value that is not valid as per the IsCardValid function and then press the Tab key; your screen should appear similar to Figure 6-15.

Figure 6-15: Custom validator control example 2

Because the value you entered does not match the value in the IsCardValid function, the function returns False and your error message is displayed.

Next, enter all 5s and click the Validate button. This time, IsCardValid returns True and your message is displayed as shown in Figure 6-16.