How to implement multicolumn loadondemand without ExternalCallBackPage

4 posts, 0 answers
  1. henk
    henk avatar
    8 posts
    Member since:
    Nov 2006

    Posted 14 Feb 2008 Link to this post

    I am migrating from RadControls to Prometheus. I got a compiler error stating that property ExternalCallBackPage no longer exist. Searching the forum I saw that I have to use a webservice instead of ExternalCallBackPage.

    However I want to create a multi column combobox using a header and item template. The webservice in the example given returns an array of RadComboBoxItemData objects. How can I use a webservice to populate a multicolumn combobox?


  2. Mike
    Mike avatar
    6 posts
    Member since:
    Jan 2008

    Posted 14 Feb 2008 Link to this post

    You don't need to use a web service.  Just set a regular event handler for OnItemsRequested and it should work fine.
  3. henk
    henk avatar
    8 posts
    Member since:
    Nov 2006

    Posted 14 Feb 2008 Link to this post


    Thanks for the answer. I have used ExternalCallBackPage sofar for a reason: my ASPX page containing the ComboBox is rather heavy. If I use the regular OnItemsRequested handler the complete page is initialised every time.

    Is a workaround available?

  4. Veselin Vasilev
    Veselin Vasilev avatar
    2992 posts

    Posted 15 Feb 2008 Link to this post

    Hi henk,

    In the Page Load event handler you can put your initialization code in the

    if (!IsPostBack && !Page.IsCallBack
     //your init code here 

    Now when you load items on demand  the IsCallBack will be true and the whole statement false so you will not initialize the page again.

    I hope this helps.

    the Telerik team

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