How many validation controls do you know?

With ASP.NET, there are six (6) controls included. They are:

1). RequiredFieldValidator

2). RangeValidator

3). CompareValidator

4). RegularExpressionValidator

5). CustomValidator

6). ValidationSummary

Note: - All of the validation controls inherit from the base class BaseValidator so they all have a series of properties and methods that are common to all validation controls. They are:

ControlToValidate – This value is which controls the validator is applied to.

ErrorMessage – This is the error message that will be displayed in the validation summary.

IsValid – Boolean value for whether or not the control is valid.

Validate – Method to validate the input control and update the IsValid property.

Display – This controls how the error message is show. Here are the possible options:

·         None (The validation message is never displayed.)

·         Static (Space for the validation message is allocated in the page layout.)

·         Dynamic (Space for the validation message is dynamically added to the page if validation fails.)

1). RequiredFieldValidator Control

Enables you to require a user to enter a value in a form field.

Example: -

RequiredFieldValidation: <asp:TextBox ID="TextBox1" runat="server"></asp:TextBox>

<asp:RequiredFieldValidator ID="RequiredFieldValidator1" runat="server"

            ControlToValidate="TextBox1" Display="Dynamic"

            ErrorMessage="* You must enter a value into textbox1"></asp:RequiredFieldValidator>

2). RangeValidator Control: -

Enables you to check whether a value falls between a certain minimum and maximum value. The attributes that are necessary to this control are: MaximumValue, MinimumValue, and Type.

Example: -

Enter a data from 1981:

<asp:TextBox ID="TextBox1" runat="server"></asp:TextBox>

<asp:RangeValidator ID="RangeValidator1" runat="server"

            ControlToValidate="TextBox1"

            ErrorMessage="* The date must be 12/15/1981 and 1/1/2010"

            MaximumValue="12/15/1981" MinimumValue="1/1/2010" Type="Date"></asp:RangeValidator>

3). CompareValidator Control: -

Enables you to compare a value against another value or perform a data type check.

Example: -

TextBox1: <asp:TextBox ID="TextBox1" runat="server"></asp:TextBox>

TextBox2: <asp:TextBox ID="TextBox2" runat="server"></asp:TextBox>

<asp:CompareValidator ID="CompareValidator1" runat="server"

            ErrorMessage="* You must enter the same values into both text box."

            ControlToCompare="TextBox2" ControlToValidate="TextBox1" Display="Dynamic"></asp:CompareValidator>

Note: - The data type can be one of: Currency, Double, Date, Integer or String. String being the default data type.

4). RegularExpressionValidator Control:

Enables you to compare a value against a regular expression.

Example: -

E-mail: - <asp:TextBox ID="TextBox1" runat="server"></asp:TextBox>

<asp:RegularExpressionValidator ID="RegularExpressionValidator1" runat="server"

            ControlToValidate="TextBox1" Display="Dynamic"

            ErrorMessage="* Please enter a valid e-mail address."

            ValidationExpression="\w+([-+.']\w+)*@\w+([-.]\w+)*\.\w+([-.]\w+)*"></asp:RegularExpressionValidator>

5). CustomValidator Control: -

Enables you to perform custom validation. Here we get to write out own functions and pass the control value to this function.

Example: -

Field:- <asp:TextBox ID="TextBox1" runat="server"></asp:TextBox>

<asp:CustomValidator ID="CustomValidator1" runat="server"

            ClientValidationFunction="ClientValidate" OnServerValidate="ServerValidate" ControlToValidate="TextBox1"

            ErrorMessage="* This box is not valid." Display="Dynamic"></asp:CustomValidator>

Note: - There are two new attributes ClientValidationFunction and OnServerValidate. ClientValidationFunction is usually a javascript function  included in the html to the user. OnServerValidate is the function that is server-side to check for validation if client does not support client-side validation.

Client Validation functions:

<script language="javascript">

/* Code goes here */

</script>

Server Validation functions:

public void ServerValidate(object obj, ServerValidateEventArgs args)

    {

        /*Code goes here */

    }

6). ValidationSummary Control: -

Enables you to display a summary of all validation error in a page.

Example: -

<asp:ValidationSummary ID="ValidationSummary1" runat="server"

            DisplayMode="List" HeaderText="Errors:" ShowMessageBox="True" />

Note: - The validation summary control will collect all the error message of all the non – valid controls and put them in a tidy list. The list can be either show on the web page or with a popup box (by specifying ShowMessageBox = “True”)