ASP.Net/Validation by Control/Validate DropDownList
RequiredFieldValidator for asp dropdownlist (C#)
<source lang="csharp">
<%@ Page Language="C#" %> <script runat="server">
void btnSubmit_Click(Object sender, EventArgs e) { if (Page.IsValid) lblResult.Text = dropFavoriteColor.SelectedValue; }
</script> <html xmlns="http://www.w3.org/1999/xhtml" > <head id="Head1" runat="server">
<title>Show Initial Value</title>
</head> <body>
<form id="form1" runat="server">
<asp:Label id="lblFavoriteColor" Text="Favorite Color:" AssociatedControlID="dropFavoriteColor" Runat="server" />
<asp:DropDownList id="dropFavoriteColor" Runat="server"> <asp:ListItem Text="Select Color" Value="none" /> <asp:ListItem Text="Red" Value="Red" /> <asp:ListItem Text="Blue" Value="Blue" /> <asp:ListItem Text="Green" Value="Green" /> </asp:DropDownList> <asp:RequiredFieldValidator id="reqFavoriteColor" Text="(Required)" InitialValue="none" ControlToValidate="dropFavoriteColor" Runat="server" />
<asp:Button id="btnSubmit" Text="Submit" Runat="server" OnClick="btnSubmit_Click" />
<asp:Label id="lblResult" Runat="server" />
</form>
</body> </html>
</source>
Validate asp dropdownlist in VB.net
<source lang="csharp">
<%@ Page Language="VB" %> <script runat="server">
Protected Sub btnSubmit_Click(ByVal sender As Object, ByVal e As System.EventArgs) If Page.IsValid Then lblResult.Text = dropFavoriteColor.SelectedValue End If End Sub
</script> <html xmlns="http://www.w3.org/1999/xhtml" > <head id="Head1" runat="server">
<title>Show Initial Value</title>
</head> <body>
<form id="form1" runat="server">
<asp:Label id="lblFavoriteColor" Text="Favorite Color:" AssociatedControlID="dropFavoriteColor" Runat="server" />
<asp:DropDownList id="dropFavoriteColor" Runat="server"> <asp:ListItem Text="Select Color" Value="none" /> <asp:ListItem Text="Red" Value="Red" /> <asp:ListItem Text="Blue" Value="Blue" /> <asp:ListItem Text="Green" Value="Green" /> </asp:DropDownList> <asp:RequiredFieldValidator id="reqFavoriteColor" Text="(Required)" InitialValue="none" ControlToValidate="dropFavoriteColor" Runat="server" />
<asp:Button id="btnSubmit" Text="Submit" Runat="server" OnClick="btnSubmit_Click" />
<asp:Label id="lblResult" Runat="server" />
</form>
</body> </html>
</source>