Validation Control In ASP .NET

Validation Control

(Maximum based on Design Time)

Purpose

        Asp .Net Validation Controls used to check whether we have entered all the Item correctly.This features used to avoid mistakes, omissions and Invalid Entries.

Example

        When creating e-mail ID, If you have the name column empty, it will generate error message like you should "enter the name". It will check whether you are eligible for the exam by referring the age. Validation Controls are

        1. RequiredFieldValidator

        2. RangeValidator

        3. RegularExpressionValidator

        4. CompareValidator

        5. CustomValidator

        6. ValidationSummary

RequiredFieldValidator

        While creating wesites we must be sure that all the data should not be empty. Required Field Validator used to avoid empty entries.

         (ex) In name column the name should be entered while creating mail-id.

How to set

        Properties ---> ControlToValidate ---> TextBox1 (or) TextBox2 etc....

        ( Select the TextBox you don't want to keep empty)

        Display ---> Dynamic/Static

Dynamic ---> Dynamic is used to display message like "wrong Entry" whenever mistakes occurs

Static ---> Used to display message always (Either mistakes is there or not)

        EnableClientScript --->True (To confirm whether we are writing coding or not)

        Text * (or) # whichever symbol you want to display when there is an error.

Syntax

<asp:RequiredFieldValidator ID="rfvusername"  runat="server"
ControlToValidate ="txtusername"  ErrorMessage="Enter the Username">
</asp:RequiredFieldValidator>

RangeValidator

        To Check whether the value in the particular control is between the specified Range. (ex) Online exam. The age limits may be between 20-30. If you enter your age "19". Display the error message "You are not eligible".

How to set

        Properties ---> Follow the same steps as for the Required Filed validator Except Range (ie) Set MaximumValue and Minimum Value

(ex) MaximumValue=80 (Means should not exceed 80)

       MinimumValue=50 (Means should not below 50)
Syntax

<asp:RangeValidator ID="RangeValidator1" runat="server"
 ErrorMessage="Enter age between 20 and 60"  ControlToValidate="txtage" ForeColor="Red" MaximumValue="60" MinimumValue="20" Type="Integer"></asp:RangeValidator>

RegularExpressionValidator

       While entering phone numbers, web addresses, pin codes there should be standard formats. For these things, if you commit a mistakes, this control would not allow you to enter the phone number etc.

       (ex) If you enter only 7 digits numbers for phone number. It won't allow the phone numbers are having 8 digits in our plan.

How to set

        Properties ---> Follow the same steps as for the Required Filed validator Except ValidationExpression ---> Like pincode format, phone number format, e-mail format.

Syntax

<asp:RegularExpressionValidator ID="remail"  runat="server" 
      ControlToValidate="txtemail" ErrorMessage="Enter your email" 
ValidationExpression="\w+([-+.']\w+)*@\w+([-.]\w+)*\.\w+([-.]\w+)*">
</asp:RegularExpressionValidator>

CompareValidator

        This control used to compare 2 entries or 2 TextBox entries. In some cases one TextBox value is based on the another TextBox values. In such situations compare validators are used.

Example : Some times we want to enter our name 2 times as in password entries. In such situation TextBox1 Value = TextBox2 Value

How to set

        Properties ---> Follow the same thing as for the previous controls. Except ControlToCompare ---> select any control ex TextBox1

ControlToValidate --->TextBox2

Select the symbol ---> < or > or =
Syntax

<asp:CompareValidator ID="cvpassword" runat="server" 
ControlToCompare="txtpassword" ControlToValidate="txtconpassword">
</asp:CompareValidator>

CustomValidator (User defined validator)

        We set our own validation rules.

How to set

 Follow the usual steps except

 ClientScript ---> False 

        This control should be designed by coding.

Example :

         Coding to check the data above 20 characters. If it is exceed 20 characters then, display the error message. 
The source code file

  <asp:TextBox runat="server" ID="txtdescription" Rows="5" TextMode="MultiLine"></asp:TextBox><br />
    <asp:CustomValidator runat="server" ID="cvdescription" ControlToValidate="txtdescription" ForeColor="Red"
        OnServerValidate="TextValidate" Text="Do not enter more than 20 characters">
    </asp:CustomValidator><br />
    <asp:Button runat="server" ID="btnSubmit" Text="Submit" />

The code behind file

 public void TextValidate(object sender, ServerValidateEventArgs args)
    {
        if (args.Value.Length == 8)
            args.IsValid = true;
        else
            args.IsValid = false;
    }

ValidationSummary

         Validation Summary used to display all the mistakes while entering forms or creating websites, as Bullet list or paragraph.

How to set

         Properties ---> Displaymode ---> select Bulletlist or paragraph

Syntax

<asp:ValidationSummary ID="ValidationSummary1" runat="server" 
      DisplayMode ="BulletList" ShowSummary ="true"
      HeaderText="Errors:" />

Note

         In all validation control you have to make clientscript = True except custom validator.

Example

Design View

The source file code

<html xmlns="http://www.w3.org/1999/xhtml" >
<head runat="server">
    <title>Registration Form</title>
</head>
<body>
    <form id="form1" runat="server">
    <div>
        
       <table style="width: 66%;">
<tr>
<td class="style1" colspan="2" align="center">
<asp:Label ID="lblmsg" 
           Text="Registration Form" 
           runat="server" />
</td>
</tr>
<tr>
<td class="style3">
    UserName:</td>
<td class="style2">
   <asp:TextBox ID="txtusername" runat="server" Width="150px"></asp:TextBox></td>
<td>
<asp:RequiredFieldValidator ID="rfvusername" 
       runat="server" ControlToValidate ="txtusername"
       ErrorMessage="Enter the Username">
</asp:RequiredFieldValidator>
</td>
</tr>
<tr>
<td class="style3" style="height: 26px">
    Password:</td>
<td class="style2" style="height: 26px">
    <asp:TextBox ID="txtpassword" runat="server" TextMode="Password" Width="150px">*</asp:TextBox></td>
<td style="height: 26px">
<asp:RequiredFieldValidator ID="rfvpassword" 
       runat="server" 
       ControlToValidate="txtpassword" 
       ErrorMessage="Enter the Password" ></asp:RequiredFieldValidator>
</td>
</tr>
<tr>
<td class="style3">
   Confirm Password:</td>
<td class="style2">
    <asp:TextBox ID="txtconpassword" runat="server" CausesValidation="True" TextMode="Password" Width="150px" ></asp:TextBox></td>
<td>
<asp:RequiredFieldValidator ID="rfvconpassword" 
       runat="server" 
       ControlToValidate="txtconpassword" 
       ErrorMessage="Enter the Confirm Password">
</asp:RequiredFieldValidator>
<asp:CompareValidator ID="cvpassword" runat="server" 
ControlToCompare="txtpassword" ControlToValidate="txtconpassword">
</asp:CompareValidator>
</td>
</tr>
<tr>
<td class="style3">
FirstName:</td>
<td class="style2">
<asp:TextBox ID="txtfirstname" runat="server" Width="150px"></asp:TextBox>
</td>
<td>
<asp:RequiredFieldValidator ID="rvfirstname" 
       runat="server" 
       ControlToValidate="txtfirstname" 
       ErrorMessage="Enter the FirstName">
</asp:RequiredFieldValidator>
</td>
</tr>
<tr>
<td class="style3">
Email:</td>
<td class="style2">
<asp:TextBox ID="txtemail" runat="server" Width="150px"></asp:TextBox>
</td>
<td>
<asp:RegularExpressionValidator ID="remail" 
      runat="server" 
      ControlToValidate="txtemail" ErrorMessage="Enter your email" 
ValidationExpression="\w+([-+.']\w+)*@\w+([-.]\w+)*\.\w+([-.]\w+)*">
</asp:RegularExpressionValidator>
</td>
</tr>
<tr>
<td class="style3">
Age:</td>
<td class="style2">
<asp:TextBox ID="txtage" runat="server" Width="150px" ></asp:TextBox>
</td>
<td>
<asp:RangeValidator ID="RangeValidator1" runat="server" ErrorMessage="Enter age between 20 and 60"
 ControlToValidate="txtage" ForeColor="Red" MaximumValue="60" MinimumValue="20" Type="Integer"></asp:RangeValidator>
</td>
</tr>
<tr>
<td class="style3" style="height: 26px">
Phone No:</td>
<td class="style2" style="height: 26px">
<asp:TextBox ID="txtmobilenumber" runat="server" Width="150px" ></asp:TextBox>
</td>
<td style="height: 26px">
<asp:RegularExpressionValidator id="rgvphone" runat="server" ControlToValidate="txtmobilenumber" 
ErrorMessage="Please Enter 10 digit Mobile Number" ValidationExpression="^[0-9]{10}"></asp:RegularExpressionValidator> </td>
</tr>
<tr>
<td class="style3" align="center" colspan="2">
<asp:Button ID="btnsubmit" runat="server" onclick="btnsubmit_Click" 
style="text-align: center" Text="Submit" Width="140px" />
</td>
</tr>
</table>
<asp:ValidationSummary ID="ValidationSummary1" runat="server" 
      DisplayMode ="BulletList" ShowSummary ="true"
      HeaderText="Errors:" />
      
</div>
</form>
</body>
</html>

The code behind for the submit button

protected void btnsubmit_Click(object sender, EventArgs e)
    {
        if (Page.IsValid)
        {
            lblmsg.Text = "Thank You";
        }
        else
        {
            lblmsg.Text = "Fill up all the fields";
        }

    }