Hi Andrew,

this issue was not there in Infragistics version 2010.2 . But when we started using Infragistics version 2017.1 , this issue is coming.

Similarly, for now, i have tried to give DropDownStyle as UltraComboStyle.DropDown then, it works fine as the current value is preserved. Why can't we do this with  DropDownList ?

But the proble with DropDown option is it allows value which are not in the drop-down collection and I don't want that.

Will you please suggest me, is there any properties defined by infragistics to overcome this issue with DropDownList ? 

Hello AOps,

I believe that before I can reliably give you any recommendations on this matter, I will need to reproduce the behavior that you are seeing locally on my end, as I am unsure why a drop-down would lose its value/text when opening the drop-down when DropDownStyle is set as DropDownList.

As such, would it be possible for you to please provide an isolated sample project that depicts the issue you are seeing. Note, our forums will only allow attachments that are < 1MB size, and so I would recommend deleting the bin and obj folders of your isolated project before attaching it.

Please let me know if you have any other questions or concerns on this matter.

One of the requirements of using DropDownList style is that the user cannot select a value that is not on the list. What's happening here is that you are handling BeforeDropDown and setting the DataSource on the UltraCombo. This causes the UltraCombo to remove all of the existing rows (including the row that matches the current value) and thus the Value gets set to null. 

Generally, it's not recommended to set the DataSource of the combo in BeforeDropDown. I expect you are doing that because your combo's list needs to change based on some other combo or some other UI option. But if that's the case, then changing the DataSource is not really the best way to go about it. It would be best to keep all possible values available on the list and filter out the ones that are not currently valid. 

If that's not the case, and you are changing the data source for some other reason, then you could get this to work in your sample by simply storing and then restoring the combo's Value. Of course, this will result in events like ValueChanged getting fired twice. So you might want to unhook them while you do it. Something like this: 

        private void UltraDropdown_BeforeDropDown(object sender, CancelEventArgs e)
        {
            var value = this.ultraCombo1.Value;
            this.ultraCombo1.ValueChanged -= UltraCombo1_ValueChanged;

            try
            {
                InitData();
                this.ultraCombo1.DataSource = ultraCombo1Data;
                this.ultraCombo1.Value = value;
            }
            finally
            {
                this.ultraCombo1.ValueChanged += UltraCombo1_ValueChanged;
            }            
        }

Thank you for the solution. It helped me resolving the Issue.