Validating Drop-Down Lists with the RequiredFieldValidator Control : RequiredFieldValidator « Validation « ASP.NET Tutorial






<%@ Page Language="VB" %>

<script runat="server">
   Protected Sub Button1_Click(ByVal sender As Object, ByVal e As System.EventArgs)
        Label1.Text = "Page is valid!"
   End Sub
</script>

<html xmlns="http://www.w3.org/1999/xhtml" >
<head id="Head1" runat="server">
    <title>RequiredFieldValidator</title>
</head>
<body>
    <form id="form1" runat="server">
    <div>
        <asp:DropDownList id="DropDownList1" runat="server">
           <asp:ListItem Selected="True">Select a profession</asp:ListItem>
           <asp:ListItem>Programmer</asp:ListItem>
           <asp:ListItem>Lawyer</asp:ListItem>
           <asp:ListItem>Doctor</asp:ListItem>
           <asp:ListItem>Artist</asp:ListItem>
        </asp:DropDownList>
        <asp:RequiredFieldValidator id="RequiredFieldValidator1" 
                                    runat="server" 
                                    ErrorMessage="Please make a selection"
                                    ControlToValidate="DropDownList1"
                                    InitialValue="Select a profession">
        </asp:RequiredFieldValidator>
        <br />
        <asp:Button ID="Button1" Runat="server" Text="Submit" 
         OnClick="Button1_Click" />
        <br />
        <br />
        <asp:Label ID="Label1" Runat="server"></asp:Label>    
    </div>
    </form>
</body>
</html>








8.11.RequiredFieldValidator
8.11.1.RequiredFieldValidator requires a user to enter a value into a form field before submitting the form.
8.11.2.Use asp:RequiredFieldValidator to check the input of an asp:TextBox (VB.net)
8.11.3.Use the RequiredFieldValidator's InitialValue to set a default value
8.11.4.Specify ErrorMessage for asp:RequiredFieldValidator
8.11.5.asp:RequiredFieldValidator will be converted to JavaScript Code after loading in client side
8.11.6.A simple use of the RequiredFieldValidator server control (C#)
8.11.7.Text field of RequiredFieldValidator server control (VB)
8.11.8.Placing values between nodes
8.11.9.Working with the InitialValue property
8.11.10.Using two RequiredFieldValidator controls for one form element
8.11.11.Validating Drop-Down Lists with the RequiredFieldValidator Control
8.11.12.Using images for error notifications
8.11.13.Disabling client-side validations in a validation control
8.11.14.Using sound for error notifications
8.11.15.EnableClientScript=false, Display=Static
8.11.16.RequiredFieldValidator for login page
8.11.17.RequiredFieldValidator with server side validation
8.11.18.Hard code error message
8.11.19.RequiredFieldValidator Dynamic Display