If statement in repeaters ItemTemplate

问题:

I'm using an ASP.NET Repeater to display the contents of a <table>. It looks something like this:

<table cellpadding="0" cellspacing="0">
    <asp:Repeater ID="checkboxList" runat="server" OnItemDataBound="OnCheckboxListItemBound">
        <ItemTemplate>
            <tr id="itemRow" runat="server">
                <td>
                    Some data
                </td>
            </tr>
        </ItemTemplate>
    </asp:Repeater>
</table>

It works fine, but i'd like to have an if() statement inside the ItemTemplate so i can conditionally determine if i want to print out a <tr> tag.

So i'd like to have something like this:

<table cellpadding="0" cellspacing="0">
    <asp:Repeater ID="checkboxList" runat="server" OnItemDataBound="OnCheckboxListItemBound">
        <ItemTemplate>

            <% if ( (CurrentItemCount % 2) == 0 ) { %?>
            <tr id="itemRow" runat="server">
            <% } %>
                <td>
                    Some data
                </td>
            <% if ( (CurrentItemCount % 2) == 0 ) { %?>
            </tr>
            <% } %>
        </ItemTemplate>
    </asp:Repeater>
</table>

Is there some way i can achieve this?

PS. The CurrentItemCount is just made up. I also need a way to get the current item count inside that if() statement. But i only seem to be able to get it from <%# Container.ItemIndex; %>, which can't be used with an if() statement?

回答1:

I would use codebehind:

protected void OnCheckboxListItemBound(Object sender, RepeaterItemEventArgs e)
{
    if (e.Item.ItemType == ListItemType.Item || e.Item.ItemType == ListItemType.AlternatingItem)
    {
        HtmlTableRow itemRow = (HtmlTableRow) e.Item.FindControl("itemRow");
        itemRow.Visible = e.Item.ItemIndex % 2 == 0;
    }
}

回答2:

Another way of doing this (if performance is not a problem):

<ItemTemplate>
  <!-- "If"  -->
  <asp:PlaceHolder runat="server" Visible="<%# MyCondition %>">
    <tr><td></td></tr>
  </asp:PlaceHolder>  
  <!-- "Else" -->
  <asp:PlaceHolder runat="server" Visible="<%# !MyCondition %>">
    <tr><td></td></tr>
  </asp:PlaceHolder>
</ItemTemplate>

回答3:

If you're trying yo make a 2 columns table this could do the trick

<%# Container.ItemIndex % 2 == 0 ? "<tr class='itemRow'>" : "" %>
    <td>
       Some data
    </td>
<%# Container.ItemIndex % 2 != 0 ? "</tr> : "" %>

Changed a couple of things: id="itemRow" for all rows would cause repeated ids what is not allowed.

Removed runat="server" since doesn't make sense on this context.

回答4:

I have 2 examples, for the examples i will bind the repeater to a array of strings (demonstration purposes only)

void BindCheckboxList()
{
 checkboxList.DataSource = new string[] { "RowA", "RowB", "RowC", "RowD", "RowE", "RowF", "RowG" };
 checkboxList.DataBind();
}

Example 1: Create a methode in de codebehind casting the bound elements back en evaluate what ever value you'd like.

Create Methode in CodeBehind (example 1):

protected string StringDataEndsWith(object dataElement, string endsWith, string  returnValue)
{
// for now an object of the type string, can be anything.
string elem = dataElement as string;
    if (elem.EndsWith(endsWith))
    {
     return returnValue; 
    }
     else
    {
     return ""; 
    }
}

In the .aspx file (example 1):

<asp:Repeater ID="checkboxList" runat="server">
<HeaderTemplate> 
    <table style="padding:0px;margin:0px;">
</HeaderTemplate> 
<ItemTemplate>
    <%# StringDataEndsWith(Container.DataItem,"A","<tr id=\"itemRow\" runat=\"server\">")  %>
    <td>
        <%# Container.DataItem  %>
    </td>
    <%# StringDataEndsWith(Container.DataItem,"G","</tr>")  %>
</ItemTemplate>
<FooterTemplate>
    </table>
</FooterTemplate>
</asp:Repeater>

Example 2: You could use a direct cast in the .aspx file

DirectCast example (no code behind):

<asp:Repeater ID="checkboxList" runat="server">
<HeaderTemplate> 
    <table style="padding:0px;margin:0px;">
</HeaderTemplate> 
<ItemTemplate>
    <%# Convert.ToString(Container.DataItem).EndsWith("A") ? "<tr id=\"itemRow\" runat=\"server\">" : ""  %>
    <td>
        <%# Container.DataItem  %>
    </td>
    <%# Convert.ToString(Container.DataItem).EndsWith("G") ? "</tr>" : ""  %>
</ItemTemplate>
<FooterTemplate>
    </table>
</FooterTemplate>
</asp:Repeater>

I hope this is what you're looking for. Regards.

回答5:

If you're wanting to do something on every other item, use the alternating item template. http://msdn.microsoft.com/en-us/library/system.web.ui.webcontrols.repeater.alternatingitemtemplate.aspx