Hi all,
Saya sedang membuat cart. Untuk menangani "add to cart" saya buat method di
store controller sbb:
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
Sedangkan ini model cart saya:
class Cart
attr_reader :items
def initialize
@items = []
end
def add_product(product)
@items << product
end
end
Anehnya saya mendapatkan NoMethodError saat klik buton "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.<<
app/models/cart.rb:9:in `add_product'
app/controllers/store_controller.rb:16:in `add_to_cart'
/usr/lib/ruby/gems/1.8/gems/actionpack-1.13.3/lib/action_controller/base.rb:1095:in
`send'
/usr/lib/ruby/gems/1.8/gems/actionpack-1.13.3/lib/action_controller/base.rb:1095:in
`perform_action_without_filters'
/usr/lib/ruby/gems/1.8/gems/actionpack-1.13.3/lib/action_controller/filters.rb:632:in
`call_filter'
/usr/lib/ruby/gems/1.8/gems/actionpack-1.13.3/lib/action_controller/filters.rb:619:in
`perform_action_without_benchmark'
/usr/lib/ruby/gems/1.8/gems/actionpack-1.13.3/lib/action_controller/benchmarking.rb:66:in
`perform_action_without_rescue'
/usr/lib/ruby/1.8/benchmark.rb:293:in `measure'
/usr/lib/ruby/gems/1.8/gems/actionpack-1.13.3/lib/action_controller/benchmarking.rb:66:in
`perform_action_without_rescue'
/usr/lib/ruby/gems/1.8/gems/actionpack-1.13.3/lib/action_controller/rescue.rb:83:in
`perform_action'
/usr/lib/ruby/gems/1.8/gems/actionpack-1.13.3/lib/action_controller/base.rb:430:in
`send'
/usr/lib/ruby/gems/1.8/gems/actionpack-1.13.3/lib/action_controller/base.rb:430:in
`process_without_filters'
/usr/lib/ruby/gems/1.8/gems/actionpack-1.13.3/lib/action_controller/filters.rb:624:in
`process_without_session_management_support'
/usr/lib/ruby/gems/1.8/gems/actionpack-1.13.3/lib/action_controller/session_management.rb:114:in
`process'
/usr/lib/ruby/gems/1.8/gems/actionpack-1.13.3/lib/action_controller/base.rb:330:in
`process'
/usr/lib/ruby/gems/1.8/gems/rails-1.2.3/lib/dispatcher.rb:41:in `dispatch'
/usr/lib/ruby/gems/1.8/gems/mongrel-0.3.13.4/lib/mongrel/rails.rb:84:in
`process'
/usr/lib/ruby/1.8/sync.rb:229:in `synchronize'
/usr/lib/ruby/gems/1.8/gems/mongrel-0.3.13.4/lib/mongrel/rails.rb:83:in
`process'
/usr/lib/ruby/gems/1.8/gems/mongrel-0.3.13.4/lib/mongrel.rb:580:in
`process_client'
/usr/lib/ruby/gems/1.8/gems/mongrel-0.3.13.4/lib/mongrel.rb:579:in `each'
/usr/lib/ruby/gems/1.8/gems/mongrel-0.3.13.4/lib/mongrel.rb:579:in
`process_client'
/usr/lib/ruby/gems/1.8/gems/mongrel-0.3.13.4/lib/mongrel.rb:686:in `run'
/usr/lib/ruby/gems/1.8/gems/mongrel-0.3.13.4/lib/mongrel.rb:686:in `initialize'
/usr/lib/ruby/gems/1.8/gems/mongrel-0.3.13.4/lib/mongrel.rb:686:in `new'
/usr/lib/ruby/gems/1.8/gems/mongrel-0.3.13.4/lib/mongrel.rb:686:in `run'
/usr/lib/ruby/gems/1.8/gems/mongrel-0.3.13.4/lib/mongrel.rb:673:in `initialize'
/usr/lib/ruby/gems/1.8/gems/mongrel-0.3.13.4/lib/mongrel.rb:673:in `new'
/usr/lib/ruby/gems/1.8/gems/mongrel-0.3.13.4/lib/mongrel.rb:673:in `run'
/usr/lib/ruby/gems/1.8/gems/mongrel-0.3.13.4/lib/mongrel/configurator.rb:267:in
`run'
/usr/lib/ruby/gems/1.8/gems/mongrel-0.3.13.4/lib/mongrel/configurator.rb:266:in
`each'
/usr/lib/ruby/gems/1.8/gems/mongrel-0.3.13.4/lib/mongrel/configurator.rb:266:in
`run'
/usr/lib/ruby/gems/1.8/gems/mongrel-0.3.13.4/bin/mongrel_rails:127:in `run'
/usr/lib/ruby/gems/1.8/gems/mongrel-0.3.13.4/lib/mongrel/command.rb:211:in `run'
/usr/lib/ruby/gems/1.8/gems/mongrel-0.3.13.4/bin/mongrel_rails:231
/usr/lib/ruby/gems/1.8/gems/activesupport-1.4.2/lib/active_support/dependencies.rb:488:in
`load'
/usr/lib/ruby/gems/1.8/gems/activesupport-1.4.2/lib/active_support/dependencies.rb:488:in
`load'
/usr/lib/ruby/gems/1.8/gems/activesupport-1.4.2/lib/active_support/dependencies.rb:342:in
`new_constants_in'
/usr/lib/ruby/gems/1.8/gems/activesupport-1.4.2/lib/active_support/dependencies.rb:488:in
`load'
/usr/lib/ruby/gems/1.8/gems/rails-1.2.3/lib/commands/servers/mongrel.rb:60
/usr/lib/ruby/vendor_ruby/1.8/rubygems/custom_require.rb:27:in
`gem_original_require'
/usr/lib/ruby/vendor_ruby/1.8/rubygems/custom_require.rb:27:in `require'
/usr/lib/ruby/gems/1.8/gems/activesupport-1.4.2/lib/active_support/dependencies.rb:495:in
`require'
/usr/lib/ruby/gems/1.8/gems/activesupport-1.4.2/lib/active_support/dependencies.rb:342:in
`new_constants_in'
/usr/lib/ruby/gems/1.8/gems/activesupport-1.4.2/lib/active_support/dependencies.rb:495:in
`require'
/usr/lib/ruby/gems/1.8/gems/rails-1.2.3/lib/commands/server.rb:39
/usr/lib/ruby/vendor_ruby/1.8/rubygems/custom_require.rb:27:in
`gem_original_require'
/usr/lib/ruby/vendor_ruby/1.8/rubygems/custom_require.rb:27:in `require'
script/server:3
app/models/cart.rb:9:in `add_product'
app/controllers/store_controller.rb:16:in `add_to_cart'
/usr/lib/ruby/gems/1.8/gems/actionpack-1.13.3/lib/action_controller/base.rb:1095:in
`send'
/usr/lib/ruby/gems/1.8/gems/actionpack-1.13.3/lib/action_controller/base.rb:1095:in
`perform_action_without_filters'
/usr/lib/ruby/gems/1.8/gems/actionpack-1.13.3/lib/action_controller/filters.rb:632:in
`call_filter'
/usr/lib/ruby/gems/1.8/gems/actionpack-1.13.3/lib/action_controller/filters.rb:619:in
`perform_action_without_benchmark'
/usr/lib/ruby/gems/1.8/gems/actionpack-1.13.3/lib/action_controller/benchmarking.rb:66:in
`perform_action_without_rescue'
/usr/lib/ruby/1.8/benchmark.rb:293:in `measure'
/usr/lib/ruby/gems/1.8/gems/actionpack-1.13.3/lib/action_controller/benchmarking.rb:66:in
`perform_action_without_rescue'
/usr/lib/ruby/gems/1.8/gems/actionpack-1.13.3/lib/action_controller/rescue.rb:83:in
`perform_action'
/usr/lib/ruby/gems/1.8/gems/actionpack-1.13.3/lib/action_controller/base.rb:430:in
`send'
/usr/lib/ruby/gems/1.8/gems/actionpack-1.13.3/lib/action_controller/base.rb:430:in
`process_without_filters'
/usr/lib/ruby/gems/1.8/gems/actionpack-1.13.3/lib/action_controller/filters.rb:624:in
`process_without_session_management_support'
/usr/lib/ruby/gems/1.8/gems/actionpack-1.13.3/lib/action_controller/session_management.rb:114:in
`process'
/usr/lib/ruby/gems/1.8/gems/actionpack-1.13.3/lib/action_controller/base.rb:330:in
`process'
/usr/lib/ruby/gems/1.8/gems/rails-1.2.3/lib/dispatcher.rb:41:in `dispatch'
/usr/lib/ruby/gems/1.8/gems/mongrel-0.3.13.4/lib/mongrel/rails.rb:84:in
`process'
/usr/lib/ruby/1.8/sync.rb:229:in `synchronize'
/usr/lib/ruby/gems/1.8/gems/mongrel-0.3.13.4/lib/mongrel/rails.rb:83:in
`process'
/usr/lib/ruby/gems/1.8/gems/mongrel-0.3.13.4/lib/mongrel.rb:580:in
`process_client'
/usr/lib/ruby/gems/1.8/gems/mongrel-0.3.13.4/lib/mongrel.rb:579:in `each'
/usr/lib/ruby/gems/1.8/gems/mongrel-0.3.13.4/lib/mongrel.rb:579:in
`process_client'
/usr/lib/ruby/gems/1.8/gems/mongrel-0.3.13.4/lib/mongrel.rb:686:in `run'
/usr/lib/ruby/gems/1.8/gems/mongrel-0.3.13.4/lib/mongrel.rb:686:in `initialize'
/usr/lib/ruby/gems/1.8/gems/mongrel-0.3.13.4/lib/mongrel.rb:686:in `new'
/usr/lib/ruby/gems/1.8/gems/mongrel-0.3.13.4/lib/mongrel.rb:686:in `run'
/usr/lib/ruby/gems/1.8/gems/mongrel-0.3.13.4/lib/mongrel.rb:673:in `initialize'
/usr/lib/ruby/gems/1.8/gems/mongrel-0.3.13.4/lib/mongrel.rb:673:in `new'
/usr/lib/ruby/gems/1.8/gems/mongrel-0.3.13.4/lib/mongrel.rb:673:in `run'
/usr/lib/ruby/gems/1.8/gems/mongrel-0.3.13.4/lib/mongrel/configurator.rb:267:in
`run'
/usr/lib/ruby/gems/1.8/gems/mongrel-0.3.13.4/lib/mongrel/configurator.rb:266:in
`each'
/usr/lib/ruby/gems/1.8/gems/mongrel-0.3.13.4/lib/mongrel/configurator.rb:266:in
`run'
/usr/lib/ruby/gems/1.8/gems/mongrel-0.3.13.4/bin/mongrel_rails:127:in `run'
/usr/lib/ruby/gems/1.8/gems/mongrel-0.3.13.4/lib/mongrel/command.rb:211:in `run'
/usr/lib/ruby/gems/1.8/gems/mongrel-0.3.13.4/bin/mongrel_rails:231
/usr/lib/ruby/gems/1.8/gems/activesupport-1.4.2/lib/active_support/dependencies.rb:488:in
`load'
/usr/lib/ruby/gems/1.8/gems/activesupport-1.4.2/lib/active_support/dependencies.rb:488:in
`load'
/usr/lib/ruby/gems/1.8/gems/activesupport-1.4.2/lib/active_support/dependencies.rb:342:in
`new_constants_in'
/usr/lib/ruby/gems/1.8/gems/activesupport-1.4.2/lib/active_support/dependencies.rb:488:in
`load'
/usr/lib/ruby/gems/1.8/gems/rails-1.2.3/lib/commands/servers/mongrel.rb:60
/usr/lib/ruby/vendor_ruby/1.8/rubygems/custom_require.rb:27:in
`gem_original_require'
/usr/lib/ruby/vendor_ruby/1.8/rubygems/custom_require.rb:27:in `require'
/usr/lib/ruby/gems/1.8/gems/activesupport-1.4.2/lib/active_support/dependencies.rb:495:in
`require'
/usr/lib/ruby/gems/1.8/gems/activesupport-1.4.2/lib/active_support/dependencies.rb:342:in
`new_constants_in'
/usr/lib/ruby/gems/1.8/gems/activesupport-1.4.2/lib/active_support/dependencies.rb:495:in
`require'
/usr/lib/ruby/gems/1.8/gems/rails-1.2.3/lib/commands/server.rb:39
/usr/lib/ruby/vendor_ruby/1.8/rubygems/custom_require.rb:27:in
`gem_original_require'
/usr/lib/ruby/vendor_ruby/1.8/rubygems/custom_require.rb:27:in `require'
script/server:3
*Parameters*: {"id"=>"2"}
*Headers*: {"cookie"=>[], "Cache-Control"=>"no-cache"}
Namun kalo saya coba di console bisa. Mengapa error ini muncul dan bagaimana
menganalisa penyebab error ini? Please help
Thanks,
Dida
[Non-text portions of this message have been removed]
