Monday, 23 June 2014

how to set required field validator with DropDownList in Asp.Net






Description:-

In this example we explain that how to set RequireField Validator for Dropdownlist and Listbox in asp.net or how to validate dropdownlist and listbox in asp.net.

We all know that in any website and web application all developer must need to validate Dropdownlist and listbox in many web forms because of that is the basic requirement in any website.

The main point must keep in mind when you have to set RequireField validator for the Dropdownlist or Listbox is that you have to set InitialValue="0" property of the RequireField validator and in Dropdownlist put this line <asp:ListItem Value="0">--Select--</asp:ListItem>


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Code:-

<%@ Page Language="C#" AutoEventWireup="true" CodeFile="validatedropdownlist.aspx.cs"
    Inherits="validatedropdownlist" %>

<!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>Validate ListBox and DropDown List using Required Field Validator</title>
</head>
<body>
    <form id="form1" runat="server">
    <div>
        <asp:ListBox ID="lstboxCountry" runat="server" Width="200px" SelectionMode="Multiple">
            <asp:ListItem Value="1">India</asp:ListItem>
            <asp:ListItem Value="2">Pakistan</asp:ListItem>
            <asp:ListItem Value="3">Austalia</asp:ListItem>
            <asp:ListItem Value="4">Japan</asp:ListItem>
            <asp:ListItem Value="5">UK</asp:ListItem>
            <asp:ListItem Value="6">USA</asp:ListItem>
           
        </asp:ListBox>
        <asp:RequiredFieldValidator ID="RequiredFieldValidator1" ControlToValidate="lstboxCountry"
            InitialValue="" runat="server" ErrorMessage="selection of country is required"></asp:RequiredFieldValidator>
    </div>
    <br />
    <div>
        <asp:DropDownList ID="drpdwnCity" runat="server" Width="200px">
            <asp:ListItem Value="0">--Select--</asp:ListItem>
            <asp:ListItem Value="1">Ahmedabad</asp:ListItem>
            <asp:ListItem Value="2">Rajkot</asp:ListItem>
            <asp:ListItem Value="3">Surat</asp:ListItem>
            <asp:ListItem Value="4">Baroda</asp:ListItem>
            <asp:ListItem Value="5">Junagadh</asp:ListItem>
            <asp:ListItem Value="6">Bhavanagar</asp:ListItem>
           
        </asp:DropDownList>
        <asp:RequiredFieldValidator ID="RequiredFieldValidator2" ControlToValidate="drpdwnCity"
            InitialValue="0" runat="server" ErrorMessage="selection of city is required"></asp:RequiredFieldValidator>
    </div>
    <br />
    <asp:Button ID="btnSubmit" runat="server" Text="Submit" />
    </form>
</body>
</html>


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