Hi Mike,

Thank you for the response and code.  More specifically, I have 4 combo controls.  I will refer to them as c1, c2, c3...  Some event sets c1's datasource = datatable.  The row selected event on all of the combos is set to load a datatable to the next combo in-line.  This code has been in Production for several months, again as a Visual Studio 2008 project and NetAdvantage 9.

Workflow:  User selects a value from c1 and a method is called from c1’s row selected event to set c2, c3 and c4’s datasource to null (to clear them) then c2’s datasource to a new datatable relevant to the value selected in C1.  User then selects a value from c2 and c2’s row selected event calls a method to set c3 and c4’s datasource to null, then c3’s datasource is set to a new datatable, etc.   The user can elect to have values selected in just c1 or all 4 combos.  It depends on the amount of filtering they want to set for an eventual button click to return data to a grid.

So it appears that the row selected event does not automatically fire when the combo's datasource is set in version 9, but now does in v 2011?  If this isn’t the case, I am willing to concede that I have no clue how to properly code this workflow.  Again, what I have has been working perfectly in the Visual Studio 2008 project with 9.2 controls.  I cannot get it to work the same in Visual Studio 2010 and 2011 controls.  My latest iteration is leaving each combo with the previously selected value regardless of what value they select.  It has been one of those weeks... :(

The error is reproducible creating two new 2011.2 UltraCombo controls, setting the DropDownStyle to DropDownList, and using the exact same code I posted above.  I do  not get the error setting the DropDownStyle to DropDown on the converted controls or the new controls.  The question is why?

In DropDownList style, it makes sense for the Combo to fire the RowSelected event when you clear the data source. It has to do this, because in DropDownList style, the Value of the control cannot contain a value that is not on the list. In other words, only values on the list are valid selections. So if the Combo has a value (non-null) and you set the DataSource to null, there will be no items on the list and therefore the Value of the control changes to null and the selected row is also set to null.

Regarding UltraDropDown, this control is intended for use with some other control like the WinGrid. It has no Value property on it - it uses the Value of whatever it is attached to (the grid cell). So the error you mention here is correct.

The take-away from this is that customers who were able to use UltraDropDown controls as DropDownLists and the .Value property outside of a grid like we did in version 9.2 will run into trouble when updating their project to a more recent version.  The conversion does not error and the application compiles but throws unmanaged code exception.  It was only when I added a 2011.2 version of the UltraDropDown did I realize it truly is now only meant to be used within a grid control.  The control tip text even states this fact.  We just happened to be victims of a not so common implementation of this control. 

JaimeZ said:

The take-away from this is that customers who were able to use UltraDropDown controls as DropDownLists and the .Value property outside of a grid like we did in version 9.2 will run into trouble when updating their project to a more recent version.

There has never been a Value property on UltraDropDown and the UltraDropDown has never been usable as a standalone control. It has always been a control that relies on being used as a dropdown by some other control such as the grid.

So I'm really not sure what you were doing with this control or why it would suddenly start causing a problem when you upgraded.

Your original post says you were using UltraCombo and it looks like you are saying that you tried using UltraDropDown instead as some sort of workaround. Are you now saying that you were using UltraDropDown all along?

The confusion on my part is with the Dropdown Style property.  The controls are UltraCombos (all along), but the Dropdown style was set to DropdownList.  I had it in my head the controls were drop downs because of this property.  Having the combos set to DropdownList is what caused the problems going from 9.2 to 11.x, with the code I had wired to the events as described above.

It the simplest level, It is frustrating when a project is successfully upgraded (using the upgrade tool) to a more recent version of the controls and code you had wired to control events no longer works resulting in an unmanged code exception.  In this case it was an evolutionary change on the control, which makes sense.  I just wish it had been caught during the upgrade process.  I am still struggling trying to use multiple combos in concert with one another where the selections made in the first drive the values in the others, whose datasources need to be first cleared and then bound to new data.

Jaime,

Did you try my suggestion?

In the sample that you are referring to try setting the "ItemMatchingMode" property of ultraCombo2 to ValueListItemMatchingMode.DoNotConvertDataValueToString

I was able to quickly reproduce the issue, which turn out to be the same issue just found this morning in my other post "Unexpected behavior changes between 9.2 and 11.2?". 

Michael S.  In your sample, simply change Combo2's .Value member to "State".  Because three of the records have "NJ" as their State, when Combo2 loses focus "Jersey City" is left in Combo2 as the selected record even if you select "Newark" or "Trenton".  This is the smoking gun and does not happen for us in our current production application using 9.2.  Changing the .Value and .DisplayMemeber to "City" is the equivalent of what I need to do to "fix" our upgraded 11.2 application.

I will update the case notes with these findings.  I do not know if it is appropriate to link case numbers in this forum for Mike S. to see, or would it be best for you to attach the sample from the case?

Thank you Micheal S. and Mike S.

This post was elevated to a Support Case, so I now have examples from both of you.  This morning I was able to modify an example for another forum post of mine dealing with a single UltraCombo to reproduce that issue, which looks like the non-unique column I set as the Combo's .Value is causing that issue, which is not an issue with the current production application running 9.2.

I will work on one of your samples now to see if I can replicate this issue with the chained Combos.

Thanks again, Jaime