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Rails Error Handling Raise

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Ruby Raise Custom Exception

Jobs Documentation Tags Users Badges Ask Question x Dismiss Join the Stack Overflow Community Stack Overflow is a community of 6.2 million rails raise exception with message programmers, just like you, helping each other. Join them; it only takes a minute: Sign up How do I raise an exception in Rails so it behaves like other Rails exceptions? up vote 51 down vote favorite ruby exception handling best practices 11 I would like to raise an exception so that it does the same thing a normal Rails exception does. Specially, show the exception and stack trace in development mode and show "We're sorry, but something went wrong" page in production mode. I tried the following: raise "safety_care group missing!" if group.nil? But it simply writes "ERROR signing up, group missing!" to the development.log file ruby-on-rails exception exception-handling share|improve this question asked Dec 16

Rails Exceptions

'09 at 22:49 Chirag Patel 2,24762433 2 the error message you posted does not seem to come from this exception (it's a different message) is this really what you're seeing? –levinalex Dec 17 '09 at 0:31 add a comment| 2 Answers 2 active oldest votes up vote 84 down vote accepted You don't have to do anything special, it should just be working. When I have a fresh rails app with this controller: class FooController < ApplicationController def index raise "error" end end and go to http://127.0.0.1:3000/foo/ I am seeing the exception with a stack trace. You might not see the whole stacktrace in the console log because Rails (since 2.3) filters lines from the stack trace that come from the framework itself. See config/initializers/backtrace_silencers.rb in your Rails project share|improve this answer edited Dec 17 '09 at 0:30 answered Dec 17 '09 at 0:11 levinalex 3,8902544 2 Excellent, concise answer. –rcd Jan 5 '14 at 22:13 The skitch link (seeing the exception with a stack trace) isn't working anymore –Asaf Jun 14 at 12:47 @levinalex will this be safe in production mode to show the stacktrace? –BKSpurgeon Aug 24 at 4:18 @levinalex - thank you alex. is there any way of adding a custom string to the error message ? –BKSpurge

and rescuing custom errors in a Rails application. It's often useful to map custom Ruby errors to HTTP response status codes and have Rails render rails raise custom exception the appropriate HTML error pages. For example, you might have a controller that ruby standard error is acting as a simple proxy to a third party service such as Twitter or Facebook, and you need any

Rails Exception Types

of the HTTP errors encountered when calling those sites to be handled natively by your app. Another use case would be in a Service-oriented architecture (SOA), where you want any errors in your http://stackoverflow.com/questions/1918373/how-do-i-raise-an-exception-in-rails-so-it-behaves-like-other-rails-exceptions back end services propagated to your front end web application. In this post we'll demonstrate rescuing status errors in an imaginary proxy controller using the awesome Faraday gem. For the sake of brevity we've omitted the inclusion of tests though in the wild we'd build such a feature using TDD and our favourite test weapon, RSpec. Not Found To start, let's handle basic 404 Not https://wearestac.com/blog/raising-and-rescuing-custom-errors-in-rails Found errors that occur when calling a service. For this we'll need a custom error class that extends StandardError. # lib/errors/not_found.rb module Errors class NotFound < StandardError; end end Faraday provides a neat Rack-esque middleware feature. By creating our own custom middleware we can catch any Faraday 404s and raise our custom error. Furthermore, we can re-use the middleware anytime we need the same behaviour. # lib/errors/raise_error.rb module Errors class RaiseError < Faraday::Response::Middleware def on_complete(env) raise Errors::NotFound if env[:status] == 404 end end end Now for the proxy controller. # app/controllers/proxy_controller.rb class ProxyController < ApplicationController def index connection = Faraday.new(:url => 'http://someservice') do |f| f.adapter Faraday.default_adapter f.use Errors::RaiseError # Include custom middleware end response = connection.get('/some/resource') render :text => response.body end end At this point any NotFounds raised will still result in a 500 Internal Server Error in Rails. To alleviate this let's create a module that uses rescue_from, catches any custom NotFounds and renders the default 404 page. # lib/errors/rescue_error.rb module Errors module RescueError def self.included(base) base.rescue_from Errors::NotFound do |e| render "public/404", :status => 404 end end end end We can then mixin RescueError into our application controller and handle NotFounds app-wide. # app/contr

deals with exceptions is strikingly similar to other languages (such as Java etc.). But, I think all the stuff I've been writing about Ruby lately has taken on a life of it's own for me :), so I am going to http://www.skorks.com/2009/09/ruby-exceptions-and-exception-handling/ quickly go over this topic if only for completeness sakes. Raising Exceptions Getting Ruby to raise https://code.tutsplus.com/articles/writing-robust-web-applications-the-lost-art-of-exception-handling--net-36395 an exception is easy :). Ruby, like many other languages has a hierarchy of exception classes (that all inherit from the class Exception), some of these are familiar and fairly easy to produce, for example ZeroDivisionError or NoMethodError. Here is some code which will do just that: 1/0 or blah = Object.new blah.hello Of course you don't have to wait for ruby raise Ruby to raise exceptions for you, you can do so explicitly in your code with the raise keyword (it is actually a method). Lets write a method where we explicitly raise an exception if the argument we pass in is false: def i_must_have_truth(value) raise TypeError, 'You must give me truth' if value == false end i_must_have_truth false this prints: D:\ruby-projects\scrap\lib\scrap.rb:15:in `i_must_have_truth': You must give me truth (TypeError) from D:\ruby-projects\scrap\lib\scrap.rb:18 As you can see we are able to raise raise exception with a specific exception and pass it a message which then gets printed out to the console. There is also a handy shortcut, if you use raise without giving it a specific exceptions (or even without giving it an error message to display), Ruby will automatically raise a RuntimeException for you which is pretty handy: def i_must_have_truth(value) raise "Hello" end i_must_have_truth false this prints: D:\ruby-projects\scrap\lib\scrap.rb:15:in `i_must_have_truth': Hello (RuntimeError) from D:\ruby-projects\scrap\lib\scrap.rb:18 Rescuing Exceptions So far so good, but life would be pretty tough if we couldn't handle the exceptions that get thrown in any way, This is where the rescue clause comes in. If we wrap some code in a begin .. end block and put a rescue clause in the middle of that, control will go to the rescue clause if any exception is thrown by the code. Let us demonstrate: begin 1/0 p 'I should never get executed' rescue p 'I am rescuing an exception and can do what I want!' end This produces the following output: "I am rescuing an exception and can do what I want!" As you can see the first string does not get printed since the division by zero will throw an exception and control will pass to the rescue clause, which will print out the second string for us. Using rescue by itself will allow you to rescue all exceptions that get thrown

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