ASP.Net Validation Controls

In this post, I will explain to you ASP.Net validation controls.

ASP.Net validation controls validate the user input data to ensure that useless, unauthenticated, or contradictory data don't get stored.

ASP.Net provides the following validation controls:

• RequiredFieldValidator
• RangeValidator
• CompareValidator
• RegularExpressionValidator
• CustomValidator
• ValidationSummary

BaseValidator Class 
The validation control classes are inherited from the BaseValidator class hence they inherit its properties and methods. Therefore, it would help to take a look at the properties and the methods of this base class, which are common for all the validation controls:

Members	Description
ControlToValidate	Indicates the input control to validate.
Display	Indicates how the error message is shown.
EnableClientScript	Indicates whether client-side validation will take.
Enabled	Enables or disables the validator.
ErrorMessage	Indicates error string.
Text	Error text to be shown if validation fails.
IsValid	Indicates whether the value of the control is valid.
SetFocusOnError	It indicates whether, in case of an invalid control, the focus should switch to the related input control.
ValidationGroup	The logical group of multiple validators, where this control belongs.
Validate()	This method revalidates the control and updates the IsValid property.

RequiredFieldValidator Control

The RequiredFieldValidator control ensures that the required field is not empty. It is generally tied to a text box to force input into the text box.

RangeValidator Control

The RangeValidator control verifies that the input value falls within a predetermined range.

CompareValidator Control

The CompareValidator control compares a value in one control with a fixed value or a value in another control.

RegularExpressionValidator

The RegularExpressionValidator allows validating the input text by matching against a pattern of a regular expression. The regular expression is set in the

CustomValidator

The CustomValidator control allows writing application-specific custom validation routines for both the client-side and the server-side validation.

The client-side validation is accomplished through the ClientValidationFunction property. The client-side validation routine should be written in a scripting language, such as JavaScript or VBScript, which the browser can understand.

The server-side validation routine must be called from the control's ServerValidate event handler. The server-side validation routine should be written in any .Net language, like C# or VB.Net.

ValidationSummary

The ValidationSummary control does not perform any validation but shows a summary of all errors on the page. The summary displays the values of the ErrorMessage property of all validation controls that failed validation.

The following two mutually inclusive properties list out the error message: 

• ShowSummary : shows the error messages in the specified format. 
• ShowMessageBox : shows the error messages in a separate window.

Validation Groups

Complex pages have different groups of information provided on different panels. In such a situation, a need might arise for performing validation separately for a separate group. This kind of situation is handled using validation groups.

To create a validation group, you should put the input controls and the validation controls into the same logical group by setting their ValidationGroupproperty.