Prevent dynamically generated radcombobox in a RadGrid to lose its selected value at time of databind.

[Ali]

I have a RadGrid which has a label, a combobox and a check box. I fill up the combobox on ItemDatabound Event of the RadGrid. What i do is create a new row on CheckedChange event of the row's CheckBox. When the grid is loaded for the first time I am storing the datasource in a session variable. When the row's checkbox is checked I am manipulating the datatable stored in session variable to add the new row in the session's datatable . I then bind the datasource of the RadGrid with the new Session Variable. I get the required RadGrid with the new row but  I am losing the selected value of all combo boxes in which a value had been selected before the checkbox was checked . I know this is the standard behaviour and there is nothing wrong with it but what i need to know is a way I can retain all the previously selected values of the comboboxes of RadGrid after the databind.

Thanks in advance.

[Eyup]

Hello Ali,

You will need to save the selected text in the created Session, or create a new Session to hold a HashTable with the DataKeyID of the row and the selected text of the related combo box. Therefore, using the ItemDataBound event you will be able to restore the selected items:
 

if (e.Item is GridDataItem)
{
    GridDataItem dataItem = e.Item as GridDataItem;
    RadComboBox combo = dataItem["YourColumn"].FindControl("YourCombo") as RadComboBox;
    Hashtable selectedItems = (Hashtable)Session["selectedItems"];
    string dataKeyID = dataItem["YourDataKeyColumn"].Text;
    string selectedItem = selectedItems[dataKeyID];
    combo.Items.FindItemByText(selectedItem).Selected = true;
}

I hope this will prove helpful.

All the best,
Eyup
the Telerik team

[Ali]

Hi Eyup,

Even I thought of something like this but the problem is that there is a combo box in each row having the same set of values for every row and I don't know how many rows would be there in the grid. On post back each and every combo box will lose the selected value, and so i would have to store each and every value by saving it in session. Is there a better approach to this scenario or would I have to continue with saving each and every value. 
I have to bind same data in combobox for each and every row, even for the newly generated row. Can anything be done there ? 

Thanks for your help.

[Eyup]

Hello Ali,

One possible approach for performance optimization would be to attach a SelectedIndexChanged event for the generated combos and save only the ones to which any modification has been made:

      ...
     combo.SelectedIndexChanged += new RadComboBoxSelectedIndexChangedEventHandler(combo_SelectedIndexChanged);
   }
protected void combo_SelectedIndexChanged(object sender, RadComboBoxSelectedIndexChangedEventArgs e)
   {
       // make the required saving operation
   }

That should do the trick.

Regards,
Eyup
the Telerik team