Should I catch exceptions only to log them?

Question

Should I catch exceptions for logging purposes?

public foo(..)
{
   try
   {
     ...
   } catch (Exception ex) {
     Logger.Error(ex);
     throw;
   }
}

If I have this in place in each of my layers (DataAccess, Business and WebService) it means the exception is logged several times.

Does it make sense to do so if my layers are in separate projects and only the public interfaces have try/catch in them? Why? Why not? Is there a different approach I could use?

Answer 1

Definitely not. You should find the correct place to handle the exception (actually do something, like catch-and-not-rethrow), and then log it. You can and should include the entire stack trace of course, but following your suggestion would litter the code with try-catch blocks.

Answer 2

Unless you are going to change the exception, you should only log at the level where you are going to handle the error and not rethrow it. Otherwise your log just has a bunch of "noise", 3 or more of the same message logged, once at each layer.

My best practice is:

1. Only try/catch in public methods (in general; obviously if you are trapping for a specific error you would check for it there)
2. Only log in the UI layer right before suppressing the error and redirecting to an error page/form.