How to capture correctly a specific exception

rubyonrails-talk
1

I a using delayed_job, and I am raising an exception this way :

config/initializers/custom_exceptions.rb    class RemoteLockerException < StandardError; end    class RemoteLockerDenied < StandardError; end

lib/instruction_request_job.rb class InstructionRequestJob < Struct.new(:style, :request_id)    def perform ....

  connector = RemoteContainerServer::Connector.create!(remote_container)   raise Exceptions::RemoteLockerDenied , "RemoteLockerDenied" if connector.nil?

....

  requestId = connector.request_job(user, remote_container)   raise Exceptions::RemoteContainerException, "RemoteContainerException" if requestId.nil?

...   end

there is a hook for any exception raised, to trap ALL the errors and do something according to the raised exception , i.e. :

    def error(job, exception)       case exception       when "RemoteContainerDenied"         .. do something       when "RemoteContainerException"         .. do something else ......       end     end

I am new to 'exception raising' ... so I initially thought I could trap the exception message : "RemoteLockerDenied" or "RemoteContainerException" as case parameter exception but it seems not working that way ...

when raised , I get #<NameError: uninitialized constant InstructionRequestJob::Exceptions> which is the exception type, not the message ... I may be ( surely) totally wrong ..... how should I proceed ?

2

I a using delayed_job, and I am raising an exception this way :

config/initializers/custom_exceptions.rb class RemoteLockerException < StandardError; end class RemoteLockerDenied < StandardError; end

This should define just RemoteLockerDenied, not Exceptions::RemoteLockerDenied.

there is a hook for any exception raised, to trap ALL the errors and do something according to the raised exception , i.e. :

def error\(job, exception\)
  case exception
  when &quot;RemoteContainerDenied&quot;
    \.\. do something
  when &quot;RemoteContainerException&quot;
    \.\. do something else \.\.\.\.\.\.
  end
end

Your whens should use the exception class, not the name, ie

when RemoteLockerDenied instead of when 'RemoteLockerDenied'

Fred

3

Thanks Fred

I believe I can pass parameters to the Exception class for fine grain processing will read more about it .. any better link than Rials doc ,

4

Thanks Fred

I believe I can pass parameters to the Exception class for fine grain processing will read more about it .. any better link than Rials doc ,

You probably want some pure ruby documentation - this isn't rails specific at all. Your subclasses of StandardError can store as many extra bits of information about the error that occurred as you want - just override the initialize method to stash the information in an instance variable or something like that

Fred

5

got it .. and it's running well , may be not the best coding , but it runs ....

in my config/initializers/custom_exceptions.rb

Module Exceptions   class RemoteContainerDenied < StandardError     def initialize(msg, remote_container_id, request_id , user_id)         super(msg)         @message = msg         @request_id = request_id         @remote_container_id = remote_container_id         @user_id = user_id     end     def message; @message + "remote_container_id: #{@remote_container_id} , requestId: #{@request_id}"; end     def remote_container_id; @remote_container_id; end     def request_id; @request_id; end     def user_id; @user_id; end   end end

raised with : raise(RemoteContainerDenied.new("Access denied", remote_container_id[:id], request[:id], user[:id] ) if response.nil?

et voilà ...

then I can trap these exceptions in delayed_job ( error hook) and act according to the exception :

def error(job, exception)     case exception     when RemoteLockerDenied         AdminMailer.....

very awesome

6

by the way, if you were to write

attr_reader :remote_container_id, :request_id, :user_id then that would write your reader methods for you

Fred

7

Hi Guys Trying to copy your code but not having any luck

All I get is "wrong number of arguments (3 for 0..1)" in the initialize call back actually referring to the .new call in the raise Can't see what I'm doing wrong.

Any help greatly appreciated

regards

dukha

module Exceptions   class IncorrectArrayFormatInYamlFile < StandardError     attr_accessible :line_number, :translation_file_id

    def initialize( msg, line_number, translation_file_id)       super(msg)       @line_number = line_number       @translation_file_id =translation_file_id     end

    def file_name       return TranslationFile.find(@translation_file_id).english_translation_file_name     end

    def message       message = @message + "line number: #{@line_number}, file: #{file_name}."     end

  end end

msg = "This file is using incorrect array format. Change file format from \" - <array_element>\" to key: [element1,element2..]. This element is on line " + line_sequence.to_s + " in " + TranslationFile.find(translation_file_id).english_translation_file_name raise Exceptions::IncorrectArrayFormatInYamlFile.new msg, line_sequence, translation_file_id