How do I hide an ASP.NET element within a listview based on value of code

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I am building an ASP.net raffle ticket system. I have a handfull of different raffles that will list details about them (type of raffle, prize won, date of drawling and prize of a ticket) below that i have a link formatted to look like a button that when clicked will take the user to a page to add this raffle to their cart. if the Raffle has had a winner, the winning ticket is displayed on the list of raffles, but the purchase button is still displayed, how can i hid this button. i have placed it in a place holder, but can't figure this next part out.

ASP.NET

 <asp:ListView ID="ListView1" runat="server" DataKeyNames="raffleID" DataSourceID="SqlDataSource1" GroupItemCount="3" ondatabound="ListView1_DataBound">

     <GroupTemplate>
         <tr id="itemPlaceholderContainer" runat="server">
             <td id="itemPlaceholder" runat="server"></td>
         </tr>
     </GroupTemplate>

     <ItemTemplate>
         <td runat="server" style="">

                 <div style="overflow: hidden;  height: 300px; width: 350px;  border-bottom-style:solid; border-bottom-color: black; border-bottom-width:1px; margin-right: 15px; margin-bottom:15px;">
                     <div style="height:70%;">
    <div style="float: left; height: 100%; width:30%;">
         <image src='images/raffles/<%# Eval("imagepath") %>'
              width="100px" height="100px" border="0">
    </div>
    <div style="float: left; height: 100%; width:65%;">

        <div>Type: <asp:Label ID="TypeLabel" runat="server" Text='<%# Eval("Type") %>' /></div>
        <div>Description: <asp:Label ID="DescriptionLabel" runat="server" Text='<%# Eval("Description") %>' /></div>
        <div>Prize: <asp:Label ID="PrizeLabel" runat="server" Text='<%# Eval("Prize") %>' /></div>
        <div>Cost: $<asp:Label ID="CostLabel" runat="server" Text='<%# Eval("Cost") %>' />\Ticket 5 for price of 4</div>
        <div>Drawling Date: <asp:Label ID="Label1" runat="server" Text='<%# Eval("DrawlingDate") %>' /></div>
        <div>Winning Ticket: <asp:Label ID="Label2" runat="server" Text='<%# Eval("TicketID") %>' /></div>
    </div>
</div>
<div style="text-align:left;">
    <asp:PlaceHolder ID="purchasebutton" runat="server" Visible='true'>
        <a class="btn btn-primary btn-lg" href="purchasetickets.aspx?raffleid=<%# Eval("raffleID") %>&ticketcost=<%# Eval("Cost") %>">Purchase Tickets »</a>
    </asp:PlaceHolder>
 </div>
                 </div>

      </td>

     </ItemTemplate>
     <LayoutTemplate>
         <table runat="server">
             <tr runat="server">
                 <td runat="server">
                     <table id="groupPlaceholderContainer" runat="server" border="0" style="">
                         <tr id="groupPlaceholder" runat="server">
                         </tr>
                     </table>
                 </td>
             </tr>
             <tr runat="server">
                 <td runat="server" style=""></td>
             </tr>
         </table>
     </LayoutTemplate>

 </asp:ListView>

basically, if the value of Eval("TicketID") is dbbull (no winner picked) set the visible property of purchasebutton place older to true, otherwise (a 6 digit number repersenting the winning ticket), set the visible property of purchasebutton to false

What I have tried:

i have tried this, but it doesn't work

ASP.NET

<asp:PlaceHolder ID="PlaceHolder1" runat="server" Visible='<%# (Eval("ImageURL") == DBNull.Value ? "true" : "False") %>'>
    <a class="btn btn-primary btn-lg" href="purchasetickets.aspx?raffleid=<%# Eval("raffleID") %>&ticketcost=<%# Eval("Cost") %>">Purchase Tickets »</a>
</asp:PlaceHolder>

Posted 11-Mar-24 10:43am

Dino the Sink

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Andre Oosthuizen · Accepted Answer · 2024-03-12T06:28:00

The easiest way to do this is to use a code-behind approach. In your 'ItemDataBound' event of the 'ListView', you can find the 'PlaceHolder' control and set its visibility accordingly -

C#

protected void ListView1_ItemDataBound(object sender, ListViewItemEventArgs e)
{
    if (e.Item.ItemType == ListViewItemType.DataItem)
    {
        //Find your PlaceHolder control...
        PlaceHolder purchaseButtonPlaceholder = (PlaceHolder)e.Item.FindControl("purchasebutton");

        //Find the Label control that displays the TicketID, change Label2 to your actual control name...
        Label ticketIdLabel = (Label)e.Item.FindControl("Label2");

        //Check if the TicketID has returned 'dbbull' (no winner picked)...
        if (ticketIdLabel.Text.Trim().ToLower() == "dbbull")
        {
            //Show your purchase button...
            purchaseButtonPlaceholder.Visible = true;
        }
        else
        {
            //Hide your purchase button...
            purchaseButtonPlaceholder.Visible = false;
        }
    }
}

In your ASPX page, you need to attach this event handler to your 'ListView' -

ASPX

<asp:ListView ID="ListView1" runat="server" DataKeyNames="raffleID" DataSourceID="SqlDataSource1" GroupItemCount="3" OnItemDataBound="ListView1_ItemDataBound">
    <!-- Your current ListView markup code here... -->
</asp:ListView>

Richard Deeming · Accepted Answer · 2024-03-18T03:41:00

Solution 2

You were so nearly there! :)

The Visible property is a bool, but you are trying to set it to a string.

Change the markup to:

ASP.NET

<asp:PlaceHolder ID="PlaceHolder1" runat="server" Visible='<%# Eval("ImageURL") == DBNull.Value ? true : false %>'>

Or, more simply:

ASP.NET

<asp:PlaceHolder ID="PlaceHolder1" runat="server" Visible='<%# Convert.IsDBNull(Eval("ImageURL")) %>'>

Posted 18-Mar-24 3:41am

Richard Deeming

v2

Comments

Dino the Sink 22-Mar-24 2:12am

the first example did not work. the complier didn't like the ? and the True and false declarations. The second example did work, The first response i got, helps a bit more. I am doing a few other operations now in the OnItemDataBound event now. But I can use this for other things!

Richard Deeming 22-Mar-24 4:50am

That's odd; are you using C# or VB? What error message did you get?

How do I hide an ASP.NET element within a listview based on value of code

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