Basic error pages
To add a few basic styles to the default error pages in Rails, just edit the
default templates
Show archive.org snapshot
in public, e.g. public/404.html.
A limitation to these default templates is that they're just static files. You cannot use Haml, Rails helpers or your application layout here. If you need Rails to render your error pages, you need the approach below.
Advanced error pages
-
Register your own app as the application responsible for showing error pages by adding
config.exceptions_app = routesto your
config/application.rb. -
Add routes for the error pages, by appending this to your
config/routes.rb:
match '/404' => 'errors#not_found', via: :all
match '/422' => 'errors#server_error', via: :all
match '/500' => 'errors#server_error', via: :all
- Add an
ErrorsControllerlike this one:
class ErrorsController < ApplicationController
skip_before_action :verify_authenticity_token
def not_found
render :status => 404, :formats => [:html]
end
def server_error
render :status => 500, :formats => [:html]
end
end
-
Add the corresponding views.
-
Delete the static error pages
404.html,422.htmland500.htmlfrompublic/. -
Add some tests, for example a cucumber feature:
@allow-rescue Scenario: 404 page When I go to the path "/foobar" Then the page should be titled "Page not found" And I should see "We're sorry, but couldn't find the page you requested" And the response status should be "404" -
(Optional) In a request spec, you'll need to stub a few config variables (in the cached Rails environment config):
# spec/requests/error_pages_spec.rb
describe "Error pages" do
def handle_errors
env_config = Rails.application.env_config
show_exceptions = env_config['action_dispatch.show_exceptions']
local_requests = env_config['action_dispatch.show_detailed_exceptions']
# Disables Rails built-in error reports, so our custom error application
# can handle them and render it's own templates. This overrides the cached
# setting in Rails.application.config.consider_all_requests_local
env_config['action_dispatch.show_detailed_exceptions'] = false
# Render exception templates instead of raising exceptions.
# This is the cached setting for
# Rails.application.config.action_dispatch.show_exceptions
env_config['action_dispatch.show_exceptions'] = true
yield
env_config['action_dispatch.show_exceptions'] = show_exceptions
env_config['action_dispatch.show_detailed_exceptions'] = local_requests
end
around(:each) do |example|
handle_errors(&example)
end
# ...
end
Additional notes
- You cannot modify headers, so you can't modify the
session,cookiesetc. - You won't see this in development, except if you set
config.consider_all_requests_local = falsein yourconfig/development.rb. - Rails will automatically choose a particular error page for some types of unhandled exceptions
