Custom component problem

Discussion in 'Microsoft Dot NET' started by Guest, Jul 31, 2005.

  1. Guest

    Guest Guest

    Hi gang,

    Not sure if this is the correct forum for this questions but here goes.

    I have developed several custom web data components and built them into a
    DLL. I reference the DLL in my VB.NET project, add a tab to the toolbar and
    add the controls beneath the tab. This all works fine, and I can drag and
    drop my controls on to the designer and all is good... until...

    If I close the designer and try to reopen it, I get an error saying

    "The file could not be loaded into the Web Forms designer. Please correct
    the following error and then try loading it again:

    Type Abstract

    Make sure all of the classes used in the page are build or referenced in the

    If I click OK then the web form loads, but I can only look at the HTML, and
    am unable to view the designer.

    Can anyone shed any light on this problem??? I am stumped.


    Guest, Jul 31, 2005
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  2. The components you have added into the new ToolBox tab loose the
    reference to the new Component DLL; their relations are not refreshed
    when you rebuild the project which contains components. I had the same
    problems. I gave up dragging dropping from the toolbar; now adding the
    html code and references manually directly in the HTML view of the
    pages. Don't forget to remove the tab that contains the custom
    component items.

    Good Luck..
    Dincer Ozturan, Aug 1, 2005
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  3. Guest

    Guest Guest

    Hi Dincer,

    Thanks for the reponse... but what do I do to get this to work? Why am I
    getting the error, and what do I need to change in the HTML to rectify it?

    Is this a known bug that is being worked on? I cannot believe that you just
    cannot create custom controls that cannot be toolboxed...

    Appreciate the help, but I need to find a solution, at least to being able
    to open the deisgner.
    Guest, Aug 1, 2005
  4. Guest

    Guest Guest

    Ok, I have figured out the problem, but am no closer to understanding it...

    In my project that has my custom controls, I have subclassed
    System.Web.UI.Page and System.Web.UI.UserControl. I have made my two
    subclasses MustInherit because I have a property that must be implemented in
    any of their subclasses (MustOverride).

    The MustInherit seems to be the culprit. If I remove that, and make the
    property Overridable, then everything is fine.

    Is there some sort of problem with setting something in this heirarchy to
    MustInherit? Or is this a bug?


    Guest, Aug 2, 2005
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