Error Handling In Rails
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Ask Question x Dismiss Join the Stack Overflow Community Stack Overflow is a community of 4.7 million programmers, just like you, helping each rails error handling view other. Join them; it only takes a minute: Sign up Rails Exception Handling up vote 9 down vote favorite 5 How can I send the error messages that are happening in the model code back to the view. https://code.tutsplus.com/articles/writing-robust-web-applications-the-lost-art-of-exception-handling--net-36395 I mean. I have a begin Some code rescue Exception Handling end now error occurs and in the rescue, I would like to send a message back to the controller, so that it ll get displayed in the view. Do I have to use a variable, which has to contain a number of error messages that occurs in one request, concatenate them and send it back to controller, so that I can display it in the view?. Rails http://stackoverflow.com/questions/3128580/rails-exception-handling already shows some error messages like field can't be blank. I am asking about the other exceptions, which occurs in the functions that are present in the model code. ruby-on-rails exception-handling share|improve this question asked Jun 27 '10 at 19:21 felix 4,97684780 add a comment| 5 Answers 5 active oldest votes up vote 6 down vote accepted Exceptions that happen as a part of saving/creating a model I use the ActiveRecord callbacks after_validation, after_validation_on_create, and before_save (depending on the circumstance), to obtain any extra data and verify that everything is ready to be saved. Then, if any problems, I store the exception in errors[:base] using add_to_base. That way the view will display the error msg in the same way it displays any other validation errors. Remember that if your before_save method returns false, the save will fail. Exceptions for other model methods All the usual methods are available: Raise a specific exception that the controller will catch. The exception can include an error number that the view translates to an error msg. Or the model can export an error_num to error_msg hash Return an error code as a return parameter of the method. Eg if you want to also use the Flash to give a positive msg when things work, you can return a msg_code. Then have negative msg codes for errors and positive codes for different types of succe
those solutions. Let me walk you through the possibilities. begin/rescue block begin/rescue blocks are the standard ruby mechanism to deal with exceptions. It might look https://blog.simplificator.com/2015/03/13/handling-errors-in-ruby-on-rails/ like this: begin do_something rescue handle_exception end This works nice for exceptions https://reinteractive.net/posts/269-exceptional-error-handling-in-ruby that might happen in your code. But what if you want to rescue every occurrence of a specific exception, say a NoPermissionError which might be raised from your security layer? Clearly you do not want to add a begin/rescue block in all your actions just to render an error handling error message, right? Around filter An around filter could be used to catch all those exceptions of a given class. Honestly I haven't used a before filter for this, this idea came to my mind when writing this blog post. class ApplicationController < ActionController::Base around_action :handle_exceptions private def handle_exceptions begin yield rescue NoPermissionError redirect_to 'permission_error' end rails error handling end end rescue_from rescue_from gives you the same possibilities as the around filter. It's just shorter and easier to read and if the framework offers a convenient way, then why not use it. There are multiple ways to define a handler for an exception, for a short and sweet handler I prefer the block syntax: class ApplicationController < ActionController::Base rescue_from 'NoPermissionError' do |exception| redirect_to 'permission_error' end end exceptions_app There is an additional feature (added in Rails 3.2) that allows to handle exceptions. You can specify an exceptions_app which is used to handle errors. You can use your own Rails app for this: config.exceptions_app = self.routes If you do so, then your routing must be configured to match error codes like so: match '/404', to: 'exceptions#handle_404' ... Alternatively you can specify a lambda which receives the whole Rack env: config.exceptions_app = lambda do |env| # do something end Do you wonder how you can call an arbitrary action when you have the env? It's pretty easy: action = ExceptionsController.action(:render_error) action.call(env) In any case you want to set following configuration for exceptions_app to be used: Rails.application.config.consider_all_requests_l
handling in Ruby By Yuji Yokoo, 18 December 2015 twitter Scroll down to read I recently come across some surprising code involving exceptions which prompted me to look a bit deeper into exceptions in Ruby. In this post, I would like to share some of what I found. Exception vs StandardError This is where it all started. I had a script that did something like the following (it was not quite this simple, but it shows the important parts): class MyLib class MyLibBaseError < Exception ; end class MyIOError < MyLibBaseError ; end def do_something raise MyIOError rescue puts "logging error: #{$!.message}" # $! is the last exception raised end end Calling do_something results in this: > MyLib.new.do_something MyLib::MyIOError: MyLib::MyIOError from (irb):70:in `do_something' from (irb):76 from /Users/yuji/.rvm/rubies/ruby-2.1.7/bin/irb:11:in `<main>' This was surprising to me: MyIOError is clearly raised, but puts is not called. This is because the blank rescue only catches StandardError and its subclasses, hence, any exception that i