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callbackpanel and viewstate Options
Sens
Posted: Tuesday, September 18, 2007 2:31:09 AM
Rank: Newbie
Groups: Member

Joined: 9/11/2007
Posts: 8
Functionality: someone clicks in productcategory: result set is built up in callbackpanel
- additional search options in parameterRepeater
- the results for the selected category in catRepeater
When pnlMenuCallback is built up, ppl can search deeper in the results through parameterRepeater.

I'm totally lost why I can't get the value of the selected dropdownboxes when the trigger (btnParamSearch) makes the panel callback. I have the generated dropdownboxes... so there no problem. But I can't access the selectedValue. It's just always 0. When I remove btnParamSearch as trigger from pnlMenuCallBack all works fine yet I have a refresh of my whole page. And I would like only a refresh of pnlMenuCallback. As info... uc1 is the treeview control.
One additional question... how to catch those annoying javascript errors for the callback panel?
Code: HTML/ASPX
<tr>
    <td>
    <asp:panel id="ProductCatpln" Runat="server">
      <uc1:productcategory id="ProductCategory" runat="server"></uc1:productcategory>
    </asp:panel>
    </td>
<EO:CallbackPanel ID="pnlMenuCallback" runat="server" GroupName="grpCallback" triggers="{ControlID:ProductCategory;Parameter:},{ControlID:btnParamSearch;Parameter:}"  OnExecute="CallbackPanelResults_Execute">
<table>
 <TR>
   <TD>
     <TABLE>
       <TR>
	<asp:repeater id="parameterRepeater" Runat="server">
	<ItemTemplate>
	<td><table><tr><td>
	<asp:Literal ID="parameterLiteral" Runat="server"></asp:Literal>
	<asp:Literal ID="PPId" Runat="server" Visible="False"></asp:Literal>
	</td></tr>
	<tr><td>
	<asp:DropDownList ID="parameterVcbo" Runat="server"></asp:DropDownList>
	</td></tr></table></td>
	</ItemTemplate>
	</asp:repeater>
            <TD vAlign="baseline"><ASP:LINKBUTTON id="btnParamSearch" runat=server Visible="False" >_Search</ASP:LINKBUTTON></TD>
        </TR>
      </TABLE>
     </TD>
   </TR>
   <TR>
     <TD>
        <TABLE>
	<asp:panel id="pnlResult" Runat="server" visible="False">
    	<TR><TD><TABLE>
	<asp:Repeater id="catRepeater" Runat="server">
	<ItemTemplate>
	<tr><td>.....</td></tr>
	</ItemTemplate>
	</asp:Repeater>
         </TABLE></TD></TR>
    </asp:panel>
  </table>
 </TD>
</TR>
</table>
</EO:CallbackPanel>


Thnx for your help.
eo_support
Posted: Tuesday, September 18, 2007 6:22:55 AM
Rank: Administration
Groups: Administration

Joined: 5/27/2007
Posts: 24,217
Your code looks fine. Since you mentioned about JavaScript error, I would start by identifying and fixing that. In order to catch the error, you want to go to your Internet Explorer -> Options to uncheck "Disable Script Debugging" options. You will then be able to invoke a Script Debugger to get more specific information about the error when it occurs.
Sens
Posted: Tuesday, September 18, 2007 6:34:56 AM
Rank: Newbie
Groups: Member

Joined: 9/11/2007
Posts: 8
I don't have javascript errors in this specific case. It's just that when btnParamSearch triggers CallbackPanelResults_Execute, it seems it doesn't take the last state of the parameterVcbo dropdownboxes. So it's impossible to find the selectedValues. Perhaps it's an issue with dynamically generated controls? I'm sure, I don't rebuild the parameterVcbo in the code behind.
eo_support
Posted: Tuesday, September 18, 2007 6:50:44 AM
Rank: Administration
Groups: Administration

Joined: 5/27/2007
Posts: 24,217
Hi,

It definitely does have to do with dynamically creating controls. This post explained how view state works in detail:

http://www.essentialobjects.com/Forum/Default.aspx?g=posts&t=347

Thanks
Sens
Posted: Wednesday, September 19, 2007 2:10:13 AM
Rank: Newbie
Groups: Member

Joined: 9/11/2007
Posts: 8
I knew you would send me this link... but my controls are buildup... it's just that I can't find the selected value. Even more... when I remove the trigger "btnParamSearch" from the panel and add the onclick event on btnParamSearch itself, it works just fine. But I don't like a complete postback of my page. Moreover... I should build up the parameters in my page_init? Won't this bring the performance down?
eo_support
Posted: Wednesday, September 19, 2007 7:08:59 AM
Rank: Administration
Groups: Administration

Joined: 5/27/2007
Posts: 24,217
Generally when you want to rebuild the control tree due to view state issues, you should do it inside Page_Init instead of Page_Load. Rebuilding controls tree in Page_Load will get the contents correctly rendered, but it will not resolve the view state issues because the flow is Page_Init -> Load View State -> Page_Load. In another word, Page_Load happens after Load view state, so whatever you do there will not help view state at all.

I don't have an explanation as why it works without trigger though. If you can create a reproducing small sample project that demonstrates the problem, we would be happy to take a look.


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