Introduction:
In this article i am going to explain how to validate asp.net controls e.g. TextBox,
CheckBox, RadioButton, DropDownList, CheckBoxList, RadioButtonList and ListBox
through code i.e. server side validation in Asp.net using both C# and VB language code.
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| Click on image to view enlarge demo |
In previous articles i explained Best example to implement stylish jQuery form validations in asp.net and JavaScript validation in asp.net website and jQuery to validate file extension and upload image file in asp.net and Show Validation/instruction guidelines using JavaScript and CustomValidator validation control with example and RegularExpressionValidator validation control with example and jQuery to Validate email address
Description: First of all the question arise What is the difference between client-side and server-side validations?
Answer is:
- Client-side validations take place at the client side with the help of JavaScript and jQuery etc before the Web page is sent to the server whereas server-side validations take place at the server end and done using programming languages like C#.Net,VB.Net etc.
- Client-side validation is faster than server-side because it takes place on client side (on browser) and the networking time from client to server is saved, whereas the server-side validation is done on the web server and server renders the data into html page and sends back to the client (browser). Thus it is bit slower.
- Client side validation can be bypassed by disabling the browser's JavaScript, so we should also validate on the server side because it protects against the malicious user, who can easily bypass our JavaScript and submit dangerous input to the server.
Implementation: Let's create a sample web page to demonstrate
the server side validation of asp.net controls.
<%@ Page Language="C#" AutoEventWireup="true" CodeFile="Default.aspx.cs" Inherits="_Default"
%>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
<title></title>
<style type="text/css">
.error
{
border: 1px
solid red;
}
.errorstyle
{
font-size: 16px;
line-height: 22px;
}
.errorstyle ul li
{
margin-left: 5px;
color: #ff0000;
}
</style>
</head>
<body>
<form id="form1" runat="server">
<div style="width:300px;">
<fieldset>
<legend>Validate TextBox</legend>
<asp:TextBox ID="txtName"
runat="server"></asp:TextBox>
</fieldset>
<fieldset>
<legend>Validate DropDownList</legend>
<asp:DropDownList ID="DropDownList1"
runat="server"
Width="150px">
<asp:ListItem Value="0" Text="--Select--"></asp:ListItem>
<asp:ListItem Value="1" Text="Asp.Net"></asp:ListItem>
<asp:ListItem Value="2" Text="MVC"></asp:ListItem>
<asp:ListItem Value="3" Text="C#"></asp:ListItem>
<asp:ListItem Value="4" Text="jQuery"></asp:ListItem>
</asp:DropDownList>
</fieldset>
<fieldset>
<legend>Validate CheckBox</legend>
<asp:CheckBox ID="CheckBox1"
runat="server"
Text="Married"
/>
</fieldset>
<fieldset>
<legend>Validate CheckBoxList</legend>
<asp:CheckBoxList ID="CheckBoxList1"
runat="server"
RepeatColumns="2">
<asp:ListItem Value="1" Text="Asp.Net"></asp:ListItem>
<asp:ListItem Value="2" Text="MVC"></asp:ListItem>
<asp:ListItem Value="3" Text="C#"></asp:ListItem>
<asp:ListItem Value="4" Text="jQuery"></asp:ListItem>
</asp:CheckBoxList>
</fieldset>
<fieldset>
<legend>Validate RadioButton</legend>
<asp:RadioButton ID="RadioButton1"
runat="server"
Text="Married"
/>
</fieldset>
<fieldset>
<legend>Validate RadioButtonList</legend>
<asp:RadioButtonList ID="RadioButtonList1"
runat="server"
RepeatColumns="2">
<asp:ListItem Value="1" Text="Asp.Net"></asp:ListItem>
<asp:ListItem Value="2" Text="MVC"></asp:ListItem>
<asp:ListItem Value="3" Text="C#"></asp:ListItem>
<asp:ListItem Value="4" Text="jQuery"></asp:ListItem>
</asp:RadioButtonList>
</fieldset>
<fieldset>
<legend>Validate ListBox</legend>
<asp:ListBox ID="ListBox1"
runat="server"
Width="150px">
<asp:ListItem Value="1" Text="Asp.Net"></asp:ListItem>
<asp:ListItem Value="2" Text="MVC"></asp:ListItem>
<asp:ListItem Value="3" Text="C#"></asp:ListItem>
<asp:ListItem Value="4" Text="jQuery"></asp:ListItem>
</asp:ListBox>
</fieldset>
<asp:Button ID="btnSubmit"
runat="server"
Text="Submit"
OnClick="btnSubmit_Click"
/>
<div class="errorstyle"
>
<asp:Literal ID="ltrlErrorMsg"
runat="server"></asp:Literal>
</div>
</div>
</form>
</body>
Asp.Net C# Code to validate
controls server side
using System.Text;
protected void btnSubmit_Click(object
sender, EventArgs e)
{
if (IsControlsValid())
{
// Form is validated. Write your submit button
code here.
}
}
private bool
IsControlsValid()
{
bool isValid = true;
StringBuilder sb = new
StringBuilder();
sb.Append("<ul>");
//Validate TextBox(can't be left empty)
if (String.IsNullOrEmpty(txtName.Text.Trim()))
{
isValid = false;
txtName.CssClass = "error";
sb.Append(String.Format("<li>{0}</li>", "Please enter in TextBox"));
}
else
{
txtName.CssClass = "";
}
//Validate DropDownList(Item must be selected)
if (DropDownList1.SelectedValue == "0")
{
isValid = false;
DropDownList1.CssClass = "error";
sb.Append(String.Format("<li>{0}</li>", "Please select DropDowlist item"));
}
else
{
DropDownList1.CssClass = "";
}
//Validate CheckBox(Must be checked)
if (!CheckBox1.Checked)
{
isValid = false;
CheckBox1.CssClass = "error";
sb.Append(String.Format("<li>{0}</li>", "Please select Checkbox"));
}
else
{
CheckBox1.CssClass = "";
}
//Validate RadioButton(Must be selected)
if (!RadioButton1.Checked)
{
isValid = false;
RadioButton1.CssClass = "error";
sb.Append(String.Format("<li>{0}</li>", "Please select RadioButton"));
}
else
{
RadioButton1.CssClass = "";
}
//Validate CheckBoxList(At least one item must be selected)
foreach (ListItem
item in CheckBoxList1.Items)
{
if (item.Selected)
{
isValid = true;
break;
}
else
{
isValid = false;
}
}
if (isValid == false)
{
CheckBoxList1.CssClass = "error";
sb.Append(String.Format("<li>{0}</li>", "Please select at least one option from
CheckBoxList"));
}
else
{
CheckBoxList1.CssClass = "";
}
//Validate RadioButton(Item must be selected)
foreach (ListItem item in
RadioButtonList1.Items)
{
if (item.Selected)
{
isValid = true;
break;
}
else
{
isValid = false;
}
}
if (isValid == false)
{
RadioButtonList1.CssClass = "error";
sb.Append(String.Format("<li>{0}</li>", "Please select at least one option from
RadioButtonList"));
}
else
{
RadioButtonList1.CssClass = "";
}
//Validate ListBox (Item must be selected)
foreach (ListItem
item in ListBox1.Items)
{
if (item.Selected)
{
isValid = true;
break;
}
else
{
isValid = false;
}
}
if (isValid == false)
{
ListBox1.CssClass = "error";
sb.Append(String.Format("<li>{0}</li>", "Please select at least one item from ListBox"));
}
else
{
ListBox1.CssClass = "";
}
sb.Append("</ul>");
ltrlErrorMsg.Text = sb.ToString();
return isValid;
}
Asp.Net VB Code to validate controls server side
Imports System.Text
Protected Sub
btnSubmit_Click(sender As Object, e As EventArgs) Handles
btnSubmit.Click
If IsControlsValid() Then
' Form is validated. Write your submit button
code here.
End If
End Sub
Private Function
IsControlsValid() As Boolean
Dim isValid As Boolean = True
Dim sb As New StringBuilder()
sb.Append("<ul>")
'Validate TextBox(Can't be left empty)
If (String.IsNullOrEmpty(txtName.Text.Trim()))
Then
isValid = False
txtName.CssClass = "error"
sb.Append(String.Format("<li>{0}</li>", "Please enter in TextBox"))
Else
txtName.CssClass = ""
End If
'Validate DropDownList(Item must be selected)
If DropDownList1.SelectedValue = "0" Then
isValid = False
DropDownList1.CssClass = "error"
sb.Append(String.Format("<li>{0}</li>", "Please select DropDowlist item"))
Else
DropDownList1.CssClass = ""
End If
'Validate CheckBox(Must be checked)
If Not
CheckBox1.Checked Then
isValid = False
CheckBox1.CssClass = "error"
sb.Append(String.Format("<li>{0}</li>", "Please select Checkbox"))
Else
CheckBox1.CssClass = ""
End If
'Validate RadioButton(Must be selected)
If Not
RadioButton1.Checked Then
isValid = False
RadioButton1.CssClass = "error"
sb.Append(String.Format("<li>{0}</li>", "Please select RadioButton"))
Else
RadioButton1.CssClass = ""
End If
'Validate CheckBoxList(At least one item must be selected)
For Each item As ListItem In CheckBoxList1.Items
If item.Selected Then
isValid = True
Exit For
Else
isValid = False
End If
Next
If isValid = False Then
CheckBoxList1.CssClass = "error"
sb.Append(String.Format("<li>{0}</li>", "Please select at least one option from
CheckBoxList"))
Else
CheckBoxList1.CssClass = ""
End If
'Validate RadioButton(Item must be selected)
For Each item As ListItem In RadioButtonList1.Items
If item.Selected Then
isValid = True
Exit For
Else
isValid = False
End If
Next
If isValid = False Then
RadioButtonList1.CssClass = "error"
sb.Append(String.Format("<li>{0}</li>", "Please select at least one option from
RadioButtonList"))
Else
RadioButtonList1.CssClass = ""
End If
'Validate ListBox (Item must be selected)
For Each item As ListItem In ListBox1.Items
If item.Selected Then
isValid = True
Exit For
Else
isValid = False
End If
Next
If isValid = False Then
ListBox1.CssClass = "error"
sb.Append(String.Format("<li>{0}</li>", "Please select at least one item from ListBox"))
Else
ListBox1.CssClass = ""
End If
sb.Append("</ul>")
ltrlErrorMsg.Text = sb.ToString()
Return isValid
End Function
" I hope you have learned how to validate asp.net controls server side using code with this example and If you like my work; you can appreciate by leaving your comments, hitting Facebook like button, following on Google+, Twitter, Linked in and Pinterest, stumbling my posts on stumble upon and subscribing for receiving free updates directly to your inbox . Stay tuned and stay connected for more technical updates."
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