Ok, here is an example where I did it. I have a datagrid with many columns. If now one column is changed to a value that is not the string "Standard" I change the value of two other column fields in the same row.

function Wdg1_CellEditing_ExitingEditMode(sender, eventArgs) 
{
   ///<summary>
   /// If the a field in Column "Basename" is not "Standard" then set the values for columns "TextA" and "TextB"
   ///</summary>
   ///<param name="sender" type="Infragistics.Web.UI.WebDataGrid"></param>
   ///<param name="eventArgs" type="Infragistics.Web.UI.CancelEditModeEventArgs"></param>
   var answers;
   var grid;
   var cellName;
   var theVal;
   
   var cell = eventArgs.getCell();

   cellName = cell.get_column().get_key();
   //the next code row gets the wrong value, it is the former value not the actual selected!! 
   //theVal = cell.get_value().toLowerCase();
   
   //the actual selected value can be found in the eventArgs!
   theVal = eventArgs.get_displayText()

   if (cellName == "Basename") 
   {
      if (theVal != "") 
      {
         if (theVal != "standard") //if not Standard then set the default values
         {
            strReturn = searchWdg2(theVal);  //here I do a "lookup" in another grid, you can also have these values already or do a query....
            answers = strReturn.split(":");  //I get 2 values in one string separated by ":" and convert this to an array
            impBCell = cell.get_row().get_cellByColumnKey("TextA");
            impBCell.set_value(answers[0]);  //put in the first value of the array

            impFCell = cell.get_row().get_cellByColumnKey("TextB");
            impFCell.set_value(answers[1]);  //put in the second value of the array
         }
      }
   }
}

I have also attached this example as txt file, so you can download an better read. I hope this help you!

Martin,

Could you please share the code you've written to accomplish this?

Thanks