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
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 (1.1ms)
Rendered /home/rubys/git/rails/actionpack/lib/action_dispatch/middleware/templates/rescues/_request_and_response.erb (2.3ms)
Rendered /home/rubys/git/rails/actionpack/lib/action_dispatch/middleware/templates/rescues/diagnostics.erb within rescues/layout (6.0ms)
 
 
Started GET "/carts/wibble" for 127.0.0.1 at 2014-02-04 15:42:04 -0500
  Processing by CartsController#show as HTML
  Parameters: {"id"=>"wibble"}
  SQL (0.3ms)   SELECT name
 FROM sqlite_master
 WHERE type = 'table' AND NOT name = 'sqlite_sequence'
  Cart Load (0.1ms)  SELECT "carts".* FROM "carts" WHERE "carts"."id" = 0 LIMIT 1
Attempt to access invalid cart wibble
Redirected to http://localhost:3000/
Completed 302 Found in 5ms
 
 
Started GET "/" for 127.0.0.1 at 2014-02-04 15:42:04 -0500
  Processing by StoreController#index as HTML
  Product Load (0.4ms)  SELECT "products".* FROM "products" ORDER BY title
Rendered store/index.html.erb within layouts/application (10.6ms)
Completed 200 OK in 20ms (Views: 12.7ms | ActiveRecord: 0.8ms)

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