Reading the great book agile web development with rails and I am running
into a problem around the pages 100.
Getting this error, I have tried rake tmp:sessions:clear and rake
db:sessions:clear but still get the the same problem.
Attached is the error message, when I try and add something to the cart
with the full trace and my code.
Thank you!
ERROR MESSAGE:
[code=]NoMethodError in StoreController#add_to_cart
You have a nil object when you didn’t expect it!
You might have expected an instance of Array.
The error occurred while evaluating nil.find
RAILS_ROOT: script/…/config/…
Application Trace | Framework Trace | Full Trace
app/models/cart.rb:9:in add_product' app/controllers/store_controller.rb:10:inadd_to_cart’
Request
Parameters: {“id”=>“3”}
Show session dump
Response
Headers: {“cookie”=>[], “Cache-Control”=>“no-cache”}[/code]
FULL TRACE
app/models/cart.rb:9:in `add_product'
app/controllers/store_controller.rb:10:in `add_to_cart'
/usr/local/lib/ruby/gems/1.8/gems/actionpack-1.13.2/lib/action_controller/base.rb:1095:in
`send'
/usr/local/lib/ruby/gems/1.8/gems/actionpack-1.13.2/lib/action_controller/base.rb:1095:in
`perform_action_without_filters'
/usr/local/lib/ruby/gems/1.8/gems/actionpack-1.13.2/lib/action_controller/filters.rb:632:in
`call_filter'
/usr/local/lib/ruby/gems/1.8/gems/actionpack-1.13.2/lib/action_controller/filters.rb:619:in
`perform_action_without_benchmark'
/usr/local/lib/ruby/gems/1.8/gems/actionpack-1.13.2/lib/action_controller/benchmarking.rb:66:in
`perform_action_without_rescue'
/usr/local/lib/ruby/1.8/benchmark.rb:293:in `measure'
/usr/local/lib/ruby/gems/1.8/gems/actionpack-1.13.2/lib/action_controller/benchmarking.rb:66:in
`perform_action_without_rescue'
/usr/local/lib/ruby/gems/1.8/gems/actionpack-1.13.2/lib/action_controller/rescue.rb:83:in
`perform_action'
/usr/local/lib/ruby/gems/1.8/gems/actionpack-1.13.2/lib/action_controller/base.rb:430:in
`send'
/usr/local/lib/ruby/gems/1.8/gems/actionpack-1.13.2/lib/action_controller/base.rb:430:in
`process_without_filters'
/usr/local/lib/ruby/gems/1.8/gems/actionpack-1.13.2/lib/action_controller/filters.rb:624:in
`process_without_session_management_support'
/usr/local/lib/ruby/gems/1.8/gems/actionpack-1.13.2/lib/action_controller/session_management.rb:114:in
`process'
/usr/local/lib/ruby/gems/1.8/gems/actionpack-1.13.2/lib/action_controller/base.rb:330:in
`process'
/usr/local/lib/ruby/gems/1.8/gems/rails-1.2.2/lib/dispatcher.rb:41:in
`dispatch'
/usr/local/lib/ruby/gems/1.8/gems/mongrel-1.0.1/lib/mongrel/rails.rb:78:in
`process'
/usr/local/lib/ruby/gems/1.8/gems/mongrel-1.0.1/lib/mongrel/rails.rb:76:in
`synchronize'
/usr/local/lib/ruby/gems/1.8/gems/mongrel-1.0.1/lib/mongrel/rails.rb:76:in
`process'
/usr/local/lib/ruby/gems/1.8/gems/mongrel-1.0.1/lib/mongrel.rb:618:in
`process_client'
/usr/local/lib/ruby/gems/1.8/gems/mongrel-1.0.1/lib/mongrel.rb:617:in
`each'
/usr/local/lib/ruby/gems/1.8/gems/mongrel-1.0.1/lib/mongrel.rb:617:in
`process_client'
/usr/local/lib/ruby/gems/1.8/gems/mongrel-1.0.1/lib/mongrel.rb:736:in
`run'
/usr/local/lib/ruby/gems/1.8/gems/mongrel-1.0.1/lib/mongrel.rb:736:in
`initialize'
/usr/local/lib/ruby/gems/1.8/gems/mongrel-1.0.1/lib/mongrel.rb:736:in
`new'
/usr/local/lib/ruby/gems/1.8/gems/mongrel-1.0.1/lib/mongrel.rb:736:in
`run'
/usr/local/lib/ruby/gems/1.8/gems/mongrel-1.0.1/lib/mongrel.rb:720:in
`initialize'
/usr/local/lib/ruby/gems/1.8/gems/mongrel-1.0.1/lib/mongrel.rb:720:in
`new'
/usr/local/lib/ruby/gems/1.8/gems/mongrel-1.0.1/lib/mongrel.rb:720:in
`run'
/usr/local/lib/ruby/gems/1.8/gems/mongrel-1.0.1/lib/mongrel/configurator.rb:271:in
`run'
/usr/local/lib/ruby/gems/1.8/gems/mongrel-1.0.1/lib/mongrel/configurator.rb:270:in
`each'
/usr/local/lib/ruby/gems/1.8/gems/mongrel-1.0.1/lib/mongrel/configurator.rb:270:in
`run'
/usr/local/lib/ruby/gems/1.8/gems/mongrel-1.0.1/bin/mongrel_rails:127:in
`run'
/usr/local/lib/ruby/gems/1.8/gems/mongrel-1.0.1/lib/mongrel/command.rb:211:in
`run'
/usr/local/lib/ruby/gems/1.8/gems/mongrel-1.0.1/bin/mongrel_rails:243
/usr/local/lib/ruby/gems/1.8/gems/activesupport-1.4.1/lib/active_support/dependencies.rb:488:in
`load'
/usr/local/lib/ruby/gems/1.8/gems/activesupport-1.4.1/lib/active_support/dependencies.rb:488:in
`load'
/usr/local/lib/ruby/gems/1.8/gems/activesupport-1.4.1/lib/active_support/dependencies.rb:342:in
`new_constants_in'
/usr/local/lib/ruby/gems/1.8/gems/activesupport-1.4.1/lib/active_support/dependencies.rb:488:in
`load'
/usr/local/lib/ruby/gems/1.8/gems/rails-1.2.2/lib/commands/servers/mongrel.rb:60
/usr/local/lib/ruby/site_ruby/1.8/rubygems/custom_require.rb:27:in
`gem_original_require'
/usr/local/lib/ruby/site_ruby/1.8/rubygems/custom_require.rb:27:in
`require'
/usr/local/lib/ruby/gems/1.8/gems/activesupport-1.4.1/lib/active_support/dependencies.rb:495:in
`require'
/usr/local/lib/ruby/gems/1.8/gems/activesupport-1.4.1/lib/active_support/dependencies.rb:342:in
`new_constants_in'
/usr/local/lib/ruby/gems/1.8/gems/activesupport-1.4.1/lib/active_support/dependencies.rb:495:in
`require'
/usr/local/lib/ruby/gems/1.8/gems/rails-1.2.2/lib/commands/server.rb:39
/usr/local/lib/ruby/site_ruby/1.8/rubygems/custom_require.rb:27:in
`gem_original_require'
/usr/local/lib/ruby/site_ruby/1.8/rubygems/custom_require.rb:27:in
`require'
script/server:3
cart.RB
[code=]class Cart
attr_reader :items
def intialize
@items = []
end
def add_product(product)
current_item = @items.find {|item| item.product == product}
if current_item
current_item.increment_quantity
else
@items << CartItem.new(product)
end
end
end[/code]
store_controller.rb
[code=]class StoreController < ApplicationController
def index
@products = Product.find_products_for_sale
end
def add_to_cart
@cart = find_cart
product = Product.find(params[:id])
@cart.add_product(product)
end
private
def find_cart
session[:cart] ||= Cart.new
end
end[/code]
cart_item.rb
[code=]class CartItem
attr_reader :product, :quantity
def intialize(product)
@product = product
@quantitiy = 1
end
def increment_quantity
@quantity += 1
end
def title
@product.title
end
def price
@product.price = @quantity
end
end[/code]