Error handling for a nicer user experience is a very tough thing to pull off correctly. Heres a simple template to make your life easier.
Controller
class ApplicationController < ActionController::Base
include ControllerExceptionsConcern
end
### app/controllers/concerns/controller_exceptions_concern.rb
module ControllerExceptionsConcern
extend ActiveSupport::Concern
included do
rescue_from Exception do |exception|
perform_error_redirect(exception, error_message: I18n.t("errors.system.general"))
end
end
private
def send_error_report(exception, sanitized_status_number)
val = true
if sanitized_status_number == 404
if !current_user && !request.referrer
### Handle Direct URL entry & Bots
val = false
end
end
if exception.class == ActionController::BadRequest
if exception.message.start_with?("Invalid query parameters: expected ")
val = false
elsif exception.message.start_with?("Invalid path parameters: Invalid encoding")
val = false
end
end
return val
end
def get_exception_status_number(exception)
status_number = 500
error_classes_404 = [
ActiveRcord::RecordNotFound,
ActionController::RoutingError,
]
if error_classes_404.include?(exception.class)
if current_user
if request.format.html? && request.get?
status_number = 404
else
status_number = 500
end
else
status_number = 404
end
end
return status_number.to_i
end
def perform_error_redirect(exception, error_message:)
request.format ||= "html"
status_number = get_exception_status_number(exception)
if send_error_report(exception, status_number)
ExceptionNotifier.notify_exception(exception, data: {status: status_number})
end
if Rails.env.development?
### To allow for the our development debugging tools
raise exception
elsif Rails.env.test?
puts exception
puts backtrace
else
logger.error exception
exception.backtrace.each do |line|
logger.error line
end
end
### Handle XHR Requests
if (request.format.html? && request.xhr?)
render template: "/errors/#{status_number}.html.erb", status: status_number
return
end
if status_number == 404
if request.format.html?
if request.get?
render template: "/errors/#{status_number}.html.erb", status: status_number
return
else
redirect_to "/#{status_number}"
end
else
head status_number
end
return
end
### Determine URL
if request.referrer.present?
url = request.referrer
else
is_admin_path = request.path.split("/").reject{|x| x.blank?}.first == "admin"
if current_user && is_admin_path && request.path.gsub("/","") != admin_root_path.gsub("/","")
url = admin_root_path
elsif request.path != "/"
url = "/"
else
if request.format.html?
if request.get?
render template: "/errors/500.html.erb", status: 500
else
redirect_to "/500"
end
else
head 500
end
return
end
end
flash_message = error_message
### Handle Redirect Based on Request Format
if request.format.html?
redirect_to url, alert: flash_message
elsif request.format.js?
flash[:alert] = flash_message
flash.keep(:alert)
render js: "window.location = "#{url}";"
else
head status_number
end
end
end
Testing
To test this in your specs you can use the following template:
Rspec.describe "Error Handling", type: :controller do
# render_views ### Enable this to actually render views if you need to validate contents
### Create anonymous controller, the anonymous controller will inherit from stated controller
controller(ApplicationController) do
def raise_500
raise StandardError.new("foobar")
end
def raise_possible_404
raise ActiveRecord::RecordNotFound
end
end
before(:all) do
@user = User.first
@error_500 = I18n.t("errors.system.general")
@error_404 = I18n.t("errors.system.not_found")
end
after(:all) do
Rails.application.reload_routes!
end
before :each do
### draw routes required for non-CRUD actions
routes.draw do
get "/anonymous/raise_500"
get "/anonymous/raise_possible_404"
end
end
describe "General Errors" do
context "Request Format: "html"" do
scenario "xhr request" do
get :raise_500, format: :html, xhr: true
expect(response).to render_template("errors/500.html.erb")
end
scenario "with referrer" do
path = "/foobar"
request.env["HTTP_REFERER"] = path
get :raise_500
expect(response).to redirect_to(path)
post :raise_500
expect(response).to redirect_to(path)
end
scenario "admin sub page" do
sign_in @user
request.path_info = "/admin/foobar"
get :raise_500
expect(response).to redirect_to(admin_root_path)
post :raise_500
expect(response).to redirect_to(admin_root_path)
end
scenario "admin root" do
sign_in @user
request.path_info = "/admin"
get :raise_500
expect(response).to redirect_to("/")
post :raise_500
expect(response).to redirect_to("/")
end
scenario "public sub-page" do
get :raise_500
expect(response).to redirect_to("/")
post :raise_500
expect(response).to redirect_to("/")
end
scenario "public root" do
request.path_info = "/"
get :raise_500
expect(response).to render_template("errors/500.html.erb")
expect(response).to have_http_status(500)
post :raise_500
expect(response).to redirect_to("/500")
end
scenario "404 error" do
get :raise_possible_404
expect(response).to render_template("errors/404.html.erb")
expect(response).to have_http_status(404)
post :raise_possible_404
expect(response).to redirect_to("/404")
sign_in @user
get :raise_possible_404
expect(response).to render_template("errors/404.html.erb")
expect(response).to have_http_status(404)
post :raise_possible_404
expect(response).to redirect_to("/")
end
end
context "Request Format: "js"" do
render_views ### Enable this to actually render views if you need to validate contents
scenario "xhr request" do
get :raise_500, format: :js, xhr: true
expect(response.body).to include("window.location = "/";")
post :raise_500, format: :js, xhr: true
expect(response.body).to include("window.location = "/";")
end
scenario "with referrer" do
path = "/foobar"
request.env["HTTP_REFERER"] = path
get :raise_500, format: :js
expect(response.body).to include("window.location = "#{path}";")
post :raise_500, format: :js
expect(response.body).to include("window.location = "#{path}";")
end
scenario "admin sub page" do
sign_in @user
request.path_info = "/admin/foobar"
get :raise_500, format: :js
expect(response.body).to include("window.location = "#{admin_root_path}";")
post :raise_500, format: :js
expect(response.body).to include("window.location = "#{admin_root_path}";")
end
scenario "admin root" do
sign_in @user
request.path_info = "/admin"
get :raise_500, format: :js
expect(response.body).to include("window.location = "/";")
post :raise_500, format: :js
expect(response.body).to include("window.location = "/";")
end
scenario "public page" do
get :raise_500, format: :js
expect(response.body).to include("window.location = "/";")
post :raise_500, format: :js
expect(response.body).to include("window.location = "/";")
end
scenario "public root" do
request.path_info = "/"
get :raise_500, format: :js
expect(response).to have_http_status(500)
post :raise_500, format: :js
expect(response).to have_http_status(500)
end
scenario "404 error" do
get :raise_possible_404, format: :js
expect(response).to have_http_status(404)
post :raise_possible_404, format: :js
expect(response).to have_http_status(404)
sign_in @user
get :raise_possible_404, format: :js
expect(response).to have_http_status(200)
expect(response.body).to include("window.location = "/";")
post :raise_possible_404, format: :js
expect(response).to have_http_status(200)
expect(response.body).to include("window.location = "/";")
end
end
context "Other Request Format" do
scenario "500 error" do
get :raise_500, format: :json
expect(response).to have_http_status(500)
post :raise_500, format: :json
expect(response).to have_http_status(500)
end
scenario "404 error" do
get :raise_possible_404, format: :json
expect(response).to have_http_status(404)
post :raise_possible_404, format: :json
expect(response).to have_http_status(404)
sign_in @user
get :raise_possible_404, format: :json
expect(response).to have_http_status(500)
post :raise_possible_404, format: :json
expect(response).to have_http_status(500)
end
end
end
end
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