[Solved] OnDemand 'Non-negative number required error'

[Liam]

Hi,

I have a on demand combobox dropdown configured to use a web service to be populated.

It works fine except in the following situation:
1 - I click on the dropdown
2 - I press the down arrow and it starts scrolling through the items
3 - When it gets to the end of the loaded items and tries to load more it pops up with the error mesage
"Non-negative number required. Parameter name: count"

This only happens when I use the down arrow to scroll through the items, if I click on the down arrow on the scroll bar then it works fine.

Any ideas how to fix this?

Cheers,
Liam.

[Simon]

Hello Liam,

In which browser did you reproduce the issue?

Could you try reproducing it in this live demo?

Finally, could you confirm the version of the Telerik.Web.UI assembly with which the issue exist at your side?

Greetings,
Simon
the Telerik team

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[Teguh]

Hi Simon,

I've similar problem.
It occurs in both IE and Firefox.
And the the telerik assembly that currently used is 2009.1.402.20
Also it happens in the demo page that you are showing. In the third sample (Page Methods)
How to reproduce:

1. Select a value from the dropdown
2. click on the bottom information of the dropdown --> Items 1-10 out of 91

the error will shows
---------------------------
Windows Internet Explorer
---------------------------
There was an error processing the request.
---------------------------
OK   
---------------------------

However in my application the error message is "Non-negative number required error"

Could you please provide workaround regarding to the problem?

Many thanks,
Teguh

[Simon]

Hello Teguh,

Thank you for the details.

We managed to reproduce the issue and will address it today. I will follow up in this thread with additional information and instructions about how to resolve the issue at your side.

Regards,
Simon
the Telerik team

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[Simon]

Hello Teguh,

I am following up regarding the issue discussed in this forum thread.

Resolving this issue will require major changes in RadComboBox's code. This will most probably break many existing implementations using the control, so we decided to introduce a new property - FilteringText - which will hold the value that has been typed in the input while loading Items on demand. 

This will allow for handling of the cases in which the issue occurs as in the online demo. The exception that is seen in the demo is actually thrown when the code gathers that data for the Items that are next to be loaded. The reason for this is that the code uses the text in the input which is different from that which has been typed, so the data base results are not as expected.

Finally, we are planning to introduce this new property with the upcoming Service Pack. We will also update the demo to show how you could use the new property.

Please bear with us some more time.

Greetings,
Simon
the Telerik team

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[Teguh]

Hi Simon,

Thank you for the response. I almost forgot that there is this issue... :P
Yes indeed, I've also made some research against to the bug, and found out that there's a problem in the code while loading the data on demand.

However I also found another problem when the dropdown item is selected, the filter is not working. When the dropdown is expanded the item shown is not filtered. This can be solved by adding a client (javascript) event handler to force the dropdown to request item everytime the selected index is changed.

the code snipped is something like this:

function OnDropdownSelectedIndexChanged(sender, eventArgs)
{
     sender.requestItems(sender.get_text(), false);
}

Hope this help the others who are having the same issue... :P

Cheers,
Teguh

[Simon]

Hi Teguh,

Yes, this is a valid workaround. Thank you for sharing it with the community, so that they can use it until the official fix.

Best wishes,
Simon
the Telerik team

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