Exception not getting caught in catch block

Question

I have a function with try, catch and finally block. If an exception is caught, then I catch certain parameters of that exception such as its error code, error detail message and message and print it in an excel file. Am posting relevant code below:

 public void UpdateGroup(String strSiteID, String strGroup,  int row)
        {
            try
            {
                Console.WriteLine("UpdateGroup");
                Excel1.MWMClient.MWMServiceProxy.Group group = new Excel1.MWMClient.MWMServiceProxy.Group();
                group.name = "plumber";
                group.description = "he is a plumber";  
                Console.WriteLine(groupClient.UpdateGroup(strSiteID,group));
                ExcelRecorder(0, null, null, row);
            }
            catch (System.ServiceModel.FaultException<DefaultFaultContract> ex)
            {
                ExcelRecorder(ex.Detail.ErrorCode, ex.Detail.Message, ex.Message, row);
            }
            finally
            {
                System.GC.Collect();
            }
        }



public void ExcelRecorder(int error, string detailmessage, string message, int row)
        {  
            Excel.Application xlApp = new Excel.Application();               
            Excel.Workbook xlWorkbook = xlApp.Workbooks.Open(@"D:/WebServiceTestCases_Output.xlsx");
            Excel._Worksheet xlWorksheet = xlWorkbook.Sheets[1];
            Excel.Range xlRange = xlWorksheet.UsedRange;           
                if (!string.IsNullOrEmpty(message))
                {
                    ((Range)xlWorksheet.Cells[row, "M"]).Value2 = "FAIL";
                    ((Range)xlWorksheet.Cells[row, "N"]).Value2 = error;
                    ((Range)xlWorksheet.Cells[row, "O"]).Value2 = detailmessage;
                    ((Range)xlWorksheet.Cells[row, "P"]).Value2 = message;
                }
                else
                {
                    ((Range)xlWorksheet.Cells[row, "M"]).Value2 = "PASS";
                    ((Range)xlWorksheet.Cells[row, "N"]).Value2 = "";
                    ((Range)xlWorksheet.Cells[row, "O"]).Value2 = "";
                    ((Range)xlWorksheet.Cells[row, "P"]).Value2 = "";
                }
            xlWorkbook.Save();
            xlWorkbook.Close(0,0,0);
            xlApp.Quit();
        }

The problem is, earlier I was having a piece of code like

catch(Exception ex)
{
ExcelRecorder(ex.Message);
}

At that time, all exceptions was getting caught. But, later the requirement got changed as I needed to capture error detail code and error detail message also. So, I changed my catch block with catch (System.ServiceModel.FaultException ex) as it allowed me to fetch those paramaters. But now, certain exceptions are not getting caught in the catch block. How can i change my catch block so that I can catch all exceptions?

Answer 1

There are basically two ways:

1: two catch blocks (most specific first):

catch (System.ServiceModel.FaultException<DefaultFaultContract> ex)
{
    ExcelRecorder(ex.Detail.ErrorCode, ex.Detail.Message, ex.Message, row);
}
catch (Exception ex)
{
    // TODO: simpler error handler
}

2: one catch block with a test:

catch (Exception ex)
{
    var fault = ex as System.ServiceModel.FaultException<DefaultFaultContract>;
    if(fault != null)
    {
        ExcelRecorder(fault.Detail.ErrorCode, fault.Detail.Message,
            fault.Message, row);
    }
    // TODO: common error handling steps
}

Either can work. The first is perhaps cleaner, but if you want to do a lot of common things inside the catch the second might have advantages.

Answer 2

Add another catch area.. You can have multiple

try
{
  // stuff
}
catch (Exception1 ex}
{
  // 1 type of exception
}
catch (Exception e)
  // catch whats left
}

Answer 3

• System.Exception is the mother of all exception types.So when you have it,will catch any kind of exception.
• But when you know a specific exception is possible in your code and have a catch block with that exception type as parameter,then that block gets a higher priority over System.Exception