How to redirect to a 404 in Rails?

Question

I'd like to 'fake' a 404 page in Rails. In PHP, I would just send a header with the error code as such:

header("HTTP/1.0 404 Not Found");

How is that done with Rails?

Answer 1

The newly Selected answer submitted by Steven Soroka is close, but not complete. The test itself hides the fact that this is not returning a true 404 - it's returning a status of 200 - "success". The original answer was closer, but attempted to render the layout as if no failure had occurred. This fixes everything:

render :text => 'Not Found', :status => '404'

Here's a typical test set of mine for something I expect to return 404, using RSpec and Shoulda matchers:

describe "user view" do
  before do
    get :show, :id => 'nonsense'
  end

  it { should_not assign_to :user }

  it { should respond_with :not_found }
  it { should respond_with_content_type :html }

  it { should_not render_template :show }
  it { should_not render_with_layout }

  it { should_not set_the_flash }
end

This healthy paranoia allowed me to spot the content-type mismatch when everything else looked peachy :) I check for all these elements: assigned variables, response code, response content type, template rendered, layout rendered, flash messages.

I'll skip the content type check on applications that are strictly html...sometimes. After all, "a skeptic checks ALL the drawers" :)

http://dilbert.com/strips/comic/1998-01-20/

FYI: I don't recommend testing for things that are happening in the controller, ie "should_raise". What you care about is the output. My tests above allowed me to try various solutions, and the tests remain the same whether the solution is raising an exception, special rendering, etc.

Answer 2

The selected answer doesn't work in Rails 3.1+ as the error handler was moved to a middleware (see github issue).

Here's the solution I found which I'm pretty happy with.

In ApplicationController:

  unless Rails.application.config.consider_all_requests_local
    rescue_from Exception, with: :handle_exception
  end

  def not_found
    raise ActionController::RoutingError.new('Not Found')
  end

  def handle_exception(exception=nil)
    if exception
      logger = Logger.new(STDOUT)
      logger.debug "Exception Message: #{exception.message} \n"
      logger.debug "Exception Class: #{exception.class} \n"
      logger.debug "Exception Backtrace: \n"
      logger.debug exception.backtrace.join("\n")
      if [ActionController::RoutingError, ActionController::UnknownController, ActionController::UnknownAction].include?(exception.class)
        return render_404
      else
        return render_500
      end
    end
  end

  def render_404
    respond_to do |format|
      format.html { render template: 'errors/not_found', layout: 'layouts/application', status: 404 }
      format.all { render nothing: true, status: 404 }
    end
  end

  def render_500
    respond_to do |format|
      format.html { render template: 'errors/internal_server_error', layout: 'layouts/application', status: 500 }
      format.all { render nothing: true, status: 500}
    end
  end

and in application.rb:

config.after_initialize do |app|
  app.routes.append{ match '*a', :to => 'application#not_found' } unless config.consider_all_requests_local
end

And in my resources (show, edit, update, delete):

@resource = Resource.find(params[:id]) or not_found

This could certainly be improved, but at least, I have different views for not_found and internal_error without overriding core Rails functions.

Answer 3

If you want to handle different 404s in different ways, consider catching them in your controllers. This will allow you to do things like tracking the number of 404s generated by different user groups, have support interact with users to find out what went wrong / what part of the user experience might need tweaking, do A/B testing, etc.

I have here placed the base logic in ApplicationController, but it can also be placed in more specific controllers, to have special logic only for one controller.

The reason I am using an if with ENV['RESCUE_404'], is so I can test the raising of AR::RecordNotFound in isolation. In tests, I can set this ENV var to false, and my rescue_from would not fire. This way I can test the raising separate from the conditional 404 logic.

class ApplicationController < ActionController::Base

  rescue_from ActiveRecord::RecordNotFound, with: :conditional_404_redirect if ENV['RESCUE_404']

private

  def conditional_404_redirect
    track_404(@current_user)
    if @current_user.present?
      redirect_to_user_home          
    else
      redirect_to_front
    end
  end

end

Answer 4

routes.rb
  get '*unmatched_route', to: 'main#not_found'

main_controller.rb
  def not_found
    render :file => "#{Rails.root}/public/404.html", :status => 404, :layout => false
  end

Answer 5

You could also use the render file:

render file: "#{Rails.root}/public/404.html", layout: false, status: 404

Where you can choose to use the layout or not.

Another option is to use the Exceptions to control it:

raise ActiveRecord::RecordNotFound, "Record not found."

Answer 6

these will help you...

Application Controller

class ApplicationController < ActionController::Base
  protect_from_forgery
  unless Rails.application.config.consider_all_requests_local             
    rescue_from ActionController::RoutingError, ActionController::UnknownController, ::AbstractController::ActionNotFound, ActiveRecord::RecordNotFound, with: lambda { |exception| render_error 404, exception }
  end

  private
    def render_error(status, exception)
      Rails.logger.error status.to_s + " " + exception.message.to_s
      Rails.logger.error exception.backtrace.join("\n") 
      respond_to do |format|
        format.html { render template: "errors/error_#{status}",status: status }
        format.all { render nothing: true, status: status }
      end
    end
end

Errors controller

class ErrorsController < ApplicationController
  def error_404
    @not_found_path = params[:not_found]
  end
end

views/errors/error_404.html.haml

.site
  .services-page 
    .error-template
      %h1
        Oops!
      %h2
        404 Not Found
      .error-details
        Sorry, an error has occured, Requested page not found!
        You tried to access '#{@not_found_path}', which is not a valid page.
      .error-actions
        %a.button_simple_orange.btn.btn-primary.btn-lg{href: root_path}
          %span.glyphicon.glyphicon-home
          Take Me Home