How to disable dropdown when not databound?

[Rick]

For some reason the dropdown is still coming up on my ComboBoxes even though they're not databound / have no items in them.

<telerik:RadComboBox ID="RadComboBox" DataSourceID="odsPopularProducts" Filter="Contains"
          DataTextField="ProductName" DataValueField="ProductID" AllowCustomText="true" MaxHeight="300"
          Width="205" OnSelectedIndexChanged="RadComboBoxProducts_SelectedIndexChanged"
          AutoPostBack="true" DropDownWidth="300" OffsetX="-95" EmptyMessage="Select a Popular Product..."
          runat="server">
</telerik:RadComboBox>

How can I stop the dropdown from displaying when there are no items in it?

[Princy]

Hi Rick,

Please try the following JavaScript in order to prevent opening the dropdown when there is no items in RadComboBox.

JavaScript:

<script type="text/javascript">
function OnClientDropDownOpening(sender, eventArgs)
{
    var combo = $find("<%= RadComboBox.ClientID %>");
    items = combo.get_items();
    if(items.get_count()==0)
    {
        eventArgs.set_cancel(true);
    }
}
</script>

Thanks,
Princy.

[Rick]

Thanks Princy,

Though I might suggest the following amendment, which allows the function to be added to an external file and utilised anywhere

            function OnClientDropDownOpening(sender, eventArgs)
            {
                items = sender.get_items();
                if(items.get_count()==0)
                     eventArgs.set_cancel(true);
            }

Why isn't this built in as standard? Why would you want a drop down to display if there's nothing in the dropdown?

Or in my case (where my MaxDropDownHeight is 300px) why would I want a dropdown of 300px to be displayed when there's nothing in the dropdown? That's surely a bug?

[Rick]

Could someone please confirm whether or not the above is a bug?

[Atanas Korchev]

Hi Rick,

This is not a bug since a lot of customers rely on this feature to load on demand the items of RadComboBox. This is used frequently to reduce the total amount of combobox item which are initially rendered. When the user opens the combobox (which is initially empty) a request to the server side is made and the items are fetched.

All the best,
Albert
the Telerik team

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[Rick]

That's a good point, cheers

[Ralf]

Hi,

I have a load on demand scenario, and I need to prevent the dropdown form opening if no data was added. I need a behavior that opens the dropdown only if data/items was received. Is this possible?

Best regards,
Ralf

[Kevin]

Hello Ralf,

To show the drop-down only when items were received you handle the OnClientItemsRequested event to show the drop-down is any items were added to the drop-down. You could also handle the OnClientItemsRequesting event to hide the drop-down as well.

I hope that helps.