any advise on exception / error handling approaches/priniciples in controllers/views???

rubyonrails-talk
1

Hi,

Can I ask for some advise re what the best practice is for handling exceptions & errors through my rails code from the point of view of how to display them back to the user? Some items I’d love to be covered include:

  • is the principle that ALL exceptions (even those the application might not to be able to do anything about) should be caught and then the application then decides what text and view .rhtml? Or should the approach be to allow exceptions to occur and the rails framework to then pass this to a general error page?

  • errors/exceptions that may occur in the action record / data layer - what categories of errors/exceptions here should be either (a) returned as call didn’t work or (b) exception. That is, from a best practice point of view are there 2 categories of errors/exceptions in the data layer that should be acknowledged and handed differently in terms of how they are captured and passed back to the controller layer? ( e.g. catch exception and process in model code and return appropriate response, OR through to an approach like: any issue that occur in the rails or database itself that get raised as an exception, don’t try to catch them, but let the exception be thrown back to the controller (at which point my first question kicks in re whether the controller should catch these areas and process or let the rails framework through to a general application error page)

  • where can I see all the possible errors like RoutingError, UnknownAction…? Is it enough to stick with the standard rails rescue_action_in_public method (see below)?

    def rescue_action_in_public(exception) #:doc:
  case exception
    when RoutingError, UnknownAction

      render_text(IO.read(File.join(RAILS_ROOT, 'public', '404.html')), "404 Not Found")
    else
      render_text(IO.read(File.join(RAILS_ROOT, 'public', '500.html')), "500 Internal Error")

  end
end

  • allocation of specific error numbers against each specific error the application catches/can create?

  • separate log file for error details in a specific parseable/setout format (e.g. for a paging system to reference) in additional to standard log file which contains various other details like rails SQL / timing information, or full exception stack details

  • an action’s render - this won’t be reached if I through an exception before this point or there is a rails exception I don’t catch before this point no?

  • anything else related to monitoring application health?

Thanks Greg

2

[bump - still very keen to hear back if possible:) ]