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LoadOnDemand persistence over PostBack

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Sergey
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Sergey asked on 13 Aug 2010, 04:43 PM
Hey, 

I'm attempting to replicate this demo ( http://demos.telerik.com/aspnet-ajax/combobox/examples/programming/addremovedisableitemsclientside/defaultcs.aspx ). The gist is that I need to either disable or hide items after they've been selected by the user. The issue I am having is that the hiding or disabling of an item is not persisted over a postback caused by the AutoPostBack property of the ComboBox. 

This seems like it should be trivial based on the 'Preserving Changes' section of http://www.telerik.com/help/aspnet-ajax/combo_clientsidebasics.html

ComboBox declaration (LinqDataSource for feeding data): 
<telerik:RadComboBox ID="SearchPeopleAttribute" runat="server" AutoPostBack="true" Skin="Windows7" AllowCustomText="true"
                       DataSourceID="SearchPeopleAttributeDS" EnableAutomaticLoadOnDemand="true" EnableVirtualScrolling="true" EnableLoadOnDemand="true" ItemsPerRequest="30" EnableItemCaching="true" Filter="Contains"  ShowMoreResultsBox="true" DataTextField="Name" DataValueField="DepartmentPersonAttributeID"
                       EmptyMessage="Search person attribute..." OnClientSelectedIndexChanging="SearchPeopleAttribute_SC" OnSelectedIndexChanged="SearchPeopleAttribute_SelectedIndexChanged" Width="175px" />

JavaScript IndexChanging:
function SearchPeopleAttribute_SC(sender, eventArgs) {
           var item = eventArgs.get_item();
           var combo = $find("<%= SearchPeopleAttribute.ClientID %>");
           //alert(combo.get_id());
           combo.trackChanges();
           //alert(item.get_text());
           item.disable();
           combo.commitChanges();
       }

Forgot to mention, .NET 4, VS 2010, Q12010 Telerik Release. 

Any suggestions? 

Cheers. 

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Cori
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answered on 13 Aug 2010, 05:38 PM
Hello Sergey,

I don't think what you're doing is possible with LoadOnDemand enabled, since LoadOnDemand will always clear the items list.
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Sergey
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answered on 16 Aug 2010, 04:08 PM
Hmm, I guess maybe I am misinterpreting the linked articles? 

If that's the case, does anyone know a good way to handle dropdowns with a very large number of items. I'm looking for something that only loads 20 or so items and the rest is through the show more functionality, or by filter. 
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Simon
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answered on 16 Aug 2010, 04:19 PM
Hello Sergey,

You are interpreting the articles correctly however the documentation for 'Preserving Changes' is incomplete - it misses to state that the functionality does not work with Load On Demand Items - so please excuse us for the caused inconvenience. We will update the article immediately.

Regarding your last question, here is a demo showing how to implement the 'show more' functionality.

Kind regards,
Simon
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Sergey
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answered on 16 Aug 2010, 07:55 PM
Hmm, noted about the doc change. Cheers. 

I ended up redoing how the page works as I want the performance that LoadOnDemand provides in this case, but I needed to also track changes and items in the combobox. 
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