Wednesday 2 November 2016

ASP.Net - fix error - Cannot have multiple items selected in a DropDownList.


Cannot have multiple items selected in a DropDownList.

Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code. 

Watch this example on YouTube:





Here is my HTML:
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
    <title></title>
</head>
<body>
    <form id="form1" runat="server">
    <div>
        <asp:DropDownList ID="DropDownList1" runat="server">
            <asp:ListItem>ONE</asp:ListItem>
            <asp:ListItem>TWO</asp:ListItem>
            <asp:ListItem>THREE</asp:ListItem>
        </asp:DropDownList>
        <asp:Button ID="Button1" runat="server" Text="Button" />
    </div>
    </form>
</body>
</html> 


And here is my code behind

        protected void Page_Load(object sender, EventArgs e)
        {
            ListItem lst = DropDownList1.Items.FindByText("ONE");
            if (lst != null)
            {
                lst.Selected = true;
            }           
        } 



To fix it replace
  lst.Selected = true;
With
                DropDownList1.SelectedIndex = DropDownList1.Items.IndexOf(DropDownList1.Items.FindByText("ONE")); 
  

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