Agile Web Development with Rails, Edition 4

10.3 Iteration E3: Finishing the Cart 10.1 Iteration E1: Creating a Smarter Cart

10.2 Iteration E2: Handling Errors

Log errors and show them on the screen.

Rescue error: log, flash, and redirect.

edit app/controllers/carts_controller.rb
class CartsController < ApplicationController
  rescue_from ActiveRecord::RecordNotFound, with: :invalid_cart
  # GET /carts
    def invalid_cart
      logger.error "Attempt to access invalid cart #{params[:id]}"
      redirect_to store_url, notice: 'Invalid cart'
    end
end

Reproduce the error.

get /carts/wibble
You are being redirected. 
get http://localhost:3000/

Invalid cart

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Inspect the log.

tail -25 log/development.log
Completed 404 Not Found in 0.8ms
 
ActiveRecord::RecordNotFound (Couldn't find Cart with id=wibble):
  app/controllers/carts_controller.rb:16:in `show'
 
 
  Rendered /home/rubys/git/rails/actionpack/lib/action_dispatch/middleware/templates/rescues/_trace.erb (0.8ms)
  Rendered /home/rubys/git/rails/actionpack/lib/action_dispatch/middleware/templates/rescues/_request_and_response.erb (0.6ms)
  Rendered /home/rubys/git/rails/actionpack/lib/action_dispatch/middleware/templates/rescues/diagnostics.erb within rescues/layout (4.2ms)
 
 
Started GET "/carts/wibble" for 127.0.0.1 at 2015-05-26 00:41:07 -0400
Processing by CartsController#show as HTML
  Parameters: {"id"=>"wibble"}
  Cart Load (0.1ms)  SELECT "carts".* FROM "carts" WHERE "carts"."id" = ? LIMIT 1  [["id", "wibble"]]
Attempt to access invalid cart wibble
Redirected to http://localhost:3000/
Completed 302 Found in 1.7ms (ActiveRecord: 0.4ms)
 
 
Started GET "/" for 127.0.0.1 at 2015-05-26 00:41:07 -0400
Processing by StoreController#index as HTML
  Product Load (0.1ms)  SELECT "products".* FROM "products" ORDER BY title
  Rendered store/index.html.erb within layouts/application (6.0ms)
Completed 200 OK in 18.1ms (Views: 14.3ms | ActiveRecord: 0.3ms)

10.3 Iteration E3: Finishing the Cart 10.1 Iteration E1: Creating a Smarter Cart