RequiredFieldValidator to validate RadioButtonList
RequiredFieldValidator validation control makes an asp.net web server
input control like a mandatory field. Input control validation fails if the
value of the control does not change from its initial value. So it will be a
required field (input control) for submitting the web form. The user must
input some value to pass the validation. You cannot pass validation by only
entering space. You can set the RequiredFieldValidator InitialValue property
to select another item except for the initial value for passing validation.
You can set the ErrorMessage property value to display an error message when
validation failed.
This example demonstrates to you how can we validate RadioButtonList control using RequiredFieldValidator. This validation control makes RadioButtonList a mandatory (required) field. So the user must select (check) a list item from RadioButtonList to pass the validation and submit the form. It is very useful when RadioButtonList has no default selection. If the validation fails, the RequiredFieldValidator shows a predefined error message that tells you RadioButtonList is a required field.
This example demonstrates to you how can we validate RadioButtonList control using RequiredFieldValidator. This validation control makes RadioButtonList a mandatory (required) field. So the user must select (check) a list item from RadioButtonList to pass the validation and submit the form. It is very useful when RadioButtonList has no default selection. If the validation fails, the RequiredFieldValidator shows a predefined error message that tells you RadioButtonList is a required field.
RadioButtonListValidation.aspx
<%@ Page Language="C#" %>
<!DOCTYPE html>
<script runat="server">
protected void Button1_Click(object sender, EventArgs e)
{
Label1.Text = "Your favorite: ";
Label1.Text += RadioButtonList1.SelectedItem.Text.ToString();
}
</script>
<html xmlns="http://www.w3.org/1999/xhtml">
<head id="Head1" runat="server">
<title>asp.net RequiredFieldValidator example: how to validate RadioButtonList</title>
</head>
<body>
<form id="form1" runat="server">
<div>
<h2 style="color:Green">RadioButtonList Validation</h2>
<asp:Label
ID="Label1"
runat="server"
Font-Size="Large"
ForeColor="Crimson"
>
</asp:Label>
<br /><br />
<asp:Label
ID="Label2"
runat="server"
Text="Favorite"
Font-Bold="true"
ForeColor="DodgerBlue"
>
</asp:Label>
<asp:RadioButtonList
ID="RadioButtonList1"
runat="server"
RepeatColumns="3"
BackColor="DodgerBlue"
ForeColor="AliceBlue"
BorderColor="DarkBlue"
BorderWidth="2"
>
<asp:ListItem>CheckBoxList</asp:ListItem>
<asp:ListItem>TreeView</asp:ListItem>
<asp:ListItem>Button</asp:ListItem>
<asp:ListItem>SqlDataSource</asp:ListItem>
<asp:ListItem>GridView</asp:ListItem>
<asp:ListItem>Calendar</asp:ListItem>
<asp:ListItem>BulletedList</asp:ListItem>
</asp:RadioButtonList>
<asp:RequiredFieldValidator
ID="ReqiredFieldValidator1"
runat="server"
ControlToValidate="RadioButtonList1"
ErrorMessage="Select your favorite!"
>
</asp:RequiredFieldValidator>
<br />
<asp:Button
ID="Button1"
runat="server"
ForeColor="DodgerBlue"
Text="Submit Favorite"
OnClick="Button1_Click"
/>
</div>
</form>
</body>
</html>
