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Can somebody explain why the selected event fires but the selection isn't honored

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ComboBox

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answered on 10 Jun 2011, 05:45 PM

Hi Dimitar

Sure I can give you some more info.

I have a RadGrid that has two columns that display images only.

In order to get filtering to work I have to place ComboBoxes in the FilterTemplate of each column.

I populated one of these combos with 4 state values:
    Text="All"                    Value="-1"
    Text="Unassigned"     Value="1"
    Text="Assigned"         Value="2"
    Text="In progress"      Value="3"

I then wrote a client side event handler for each combo that would fire on a selection change.

In those event handlers I obtained the combobox item's value attribute.

Here's the event handler code for one of the combos.

          var tableView   = $find("<%# ((GridItem)Container).OwnerTableView.ClientID %>");
          var value       = args.get_item().get_value();

          // This is just to show the event handler fired, and that I have the expected value.
          alert( value.toString() );

          if ( value < 0 )
          {
              tableView.filter( "StateUnique", value , "NoFilter" );
          }
          else
          {
                tableView.filter( "StateUnique", value , "EqualTo" );
           }

The 'All' item is the default, and that appears in the input area of the combo on initial page load.

I then make a selection, for instance 'Unapproved'.

While the code is stopped at the alert I see 'Unapproved' in the input area of the combo.
So clearly the client side event fired, and I can tell from the alert that I have a value of 1.

So far so good.

I respond to the alert and can tell from a break-point in my code behind that a post-back occurs.

The grid gets filtered just fine.

However after the post-back the combobox input area is set back to 'All'.

So I can never get a selection change event to fire when I click the 'All' item in the combo dropdown area.

I have read several articles on your web-site that indicate the following:

I am including the process I went through so you understand the problems I've had and so will others.

1. Combos remember their state across Post-backs IF you have ViewState enabled on the page AND the control.
    Also you have to set ViewStateMode = Enabled.
    This doesn't cause the combos to remember their state in my scenario.
    Am I missing something?
    I even enabled ViewState on my parent grid.

2. I found an example in your on your website @
http://demos.telerik.com/aspnet-ajax/grid/examples/programming/filteringtemplatecolumns/defaultcs.aspx

This example finally gave me a solution that worked, but required me to sub-class the grid columns.
However I went ahead and implemented this, although it seemed more involved than I would have liked.

3. Finally I stumbled across a different example @
http://demos.telerik.com/aspnet-ajax/grid/examples/programming/filtertemplate/defaultcs.aspx
This gave me the solution I prefer.
Add the following to the definition of my comboboxes:

SelectedValue

='<%# ((GridItem)Container).OwnerTableView.GetColumn("StateUnique").CurrentFilterValue %>'

Obvious the column name is different for each of my columns.

For some reason I can only get this to work in my code if I add the ComboBox Items in my aspx file,
rather than dynamically, but I expect that is a coding error on my part.

HTH