购物车阵列出现问题，cart.total_price

Question

I'm programming a cart system for one website in RoR and I have a strange problem with my cart.

I already made another app with the same cart model and didn't have this problem.

So here is the situation:

• add product to my cart, that's ok.
• write cart.total_item, that's ok.
• write cart.total_price, this fail.

My app tell me the ' method ' I'm trying to use to calculate ' cart.total _ price ' is ' undefined '.

Here is the record:

Showing /var/rails/caveSACMS/app/views/catalogues/index.html.erb where line #196 raised:

undefined method `prod_pxuttc' for #<Array:0x00000005ce09f0>

Extracted source (around line #196):

193:       </tr>
    194:       <tr style="background-color:#2c2c2c;">
    195:         <th style="text-align:center;padding:2px;color:#a2a2a2;">
    196:           Total: <%=@cart.total_price%>
    197:         </th>
    198:       </tr>
    199:       <tr style="background-color:#2c2c2c;">

Rails.root: /var/rails/myApp

app/models/cart.rb:15:in `block in total_price'
    activesupport (3.2.1) lib/active_support/core_ext/enumerable.rb:60:in `map'
    activesupport (3.2.1) lib/active_support/core_ext/enumerable.rb:60:in `sum'
    app/models/cart.rb:15:in `total_price'
    app/views/catalogues/index.html.erb:196:in `_app_views_catalogues_index_html_erb___2685208389527055012_43230480'
    actionpack (3.2.1) lib/action_view/template.rb:143:in `block in render'
    activesupport (3.2.1) lib/active_support/notifications.rb:125:in `instrument'
    actionpack (3.2.1) lib/action_view/template.rb:141:in `render'
    actionpack (3.2.1) lib/action_view/renderer/template_renderer.rb:41:in `block (2 levels) in render_template'
    actionpack (3.2.1) lib/action_view/renderer/abstract_renderer.rb:38:in `block in instrument'
    activesupport (3.2.1) lib/active_support/notifications.rb:123:in `block in instrument'
    activesupport (3.2.1) lib/active_support/notifications/instrumenter.rb:20:in `instrument'
    activesupport (3.2.1) lib/active_support/notifications.rb:123:in `instrument'
    actionpack (3.2.1) lib/action_view/renderer/abstract_renderer.rb:38:in `instrument'
    actionpack (3.2.1) lib/action_view/renderer/template_renderer.rb:40:in `block in render_template'
    actionpack (3.2.1) lib/action_view/renderer/template_renderer.rb:48:in `render_with_layout'
    actionpack (3.2.1) lib/action_view/renderer/template_renderer.rb:39:in `render_template'
    actionpack (3.2.1) lib/action_view/renderer/template_renderer.rb:12:in `render'
    actionpack (3.2.1) lib/action_view/renderer/renderer.rb:36:in `render_template'
    actionpack (3.2.1) lib/action_view/renderer/renderer.rb:17:in `render'
    actionpack (3.2.1) lib/abstract_controller/rendering.rb:109:in `_render_template'
    actionpack (3.2.1) lib/action_controller/metal/streaming.rb:225:in `_render_template'
    actionpack (3.2.1) lib/abstract_controller/rendering.rb:103:in `render_to_body'
    actionpack (3.2.1) lib/action_controller/metal/renderers.rb:28:in `render_to_body'
    actionpack (3.2.1) lib/action_controller/metal/compatibility.rb:50:in `render_to_body'
    actionpack (3.2.1) lib/abstract_controller/rendering.rb:88:in `render'
    actionpack (3.2.1) lib/action_controller/metal/rendering.rb:16:in `render'
    actionpack (3.2.1) lib/action_controller/metal/instrumentation.rb:40:in `block (2 levels) in render'
    activesupport (3.2.1) lib/active_support/core_ext/benchmark.rb:5:in `block in ms'
    /usr/share/ruby-rvm/rubies/ruby-1.9.2-p290/lib/ruby/1.9.1/benchmark.rb:310:in `realtime'
    activesupport (3.2.1) lib/active_support/core_ext/benchmark.rb:5:in `ms'
    actionpack (3.2.1) lib/action_controller/metal/instrumentation.rb:40:in `block in render'
    actionpack (3.2.1) lib/action_controller/metal/instrumentation.rb:83:in `cleanup_view_runtime'
    activerecord (3.2.1) lib/active_record/railties/controller_runtime.rb:24:in `cleanup_view_runtime'
    actionpack (3.2.1) lib/action_controller/metal/instrumentation.rb:39:in `render'
    actionpack (3.2.1) lib/action_controller/metal/implicit_render.rb:10:in `default_render'
    actionpack (3.2.1) lib/action_controller/metal/implicit_render.rb:5:in `send_action'
    actionpack (3.2.1) lib/abstract_controller/base.rb:167:in `process_action'
    actionpack (3.2.1) lib/action_controller/metal/rendering.rb:10:in `process_action'
    actionpack (3.2.1) lib/abstract_controller/callbacks.rb:18:in `block in process_action'
    activesupport (3.2.1) lib/active_support/callbacks.rb:414:in `_run__1902602080326961788__process_action__2511143183103068215__callbacks'
    activesupport (3.2.1) lib/active_support/callbacks.rb:405:in `__run_callback'
    activesupport (3.2.1) lib/active_support/callbacks.rb:385:in `_run_process_action_callbacks'
    activesupport (3.2.1) lib/active_support/callbacks.rb:81:in `run_callbacks'
    actionpack (3.2.1) lib/abstract_controller/callbacks.rb:17:in `process_action'
    actionpack (3.2.1) lib/action_controller/metal/rescue.rb:29:in `process_action'
    actionpack (3.2.1) lib/action_controller/metal/instrumentation.rb:30:in `block in process_action'
    activesupport (3.2.1) lib/active_support/notifications.rb:123:in `block in instrument'
    activesupport (3.2.1) lib/active_support/notifications/instrumenter.rb:20:in `instrument'
    activesupport (3.2.1) lib/active_support/notifications.rb:123:in `instrument'
    actionpack (3.2.1) lib/action_controller/metal/instrumentation.rb:29:in `process_action'
    actionpack (3.2.1) lib/action_controller/metal/params_wrapper.rb:205:in `process_action'
    activerecord (3.2.1) lib/active_record/railties/controller_runtime.rb:18:in `process_action'
    actionpack (3.2.1) lib/abstract_controller/base.rb:121:in `process'
    actionpack (3.2.1) lib/abstract_controller/rendering.rb:45:in `process'
    actionpack (3.2.1) lib/action_controller/metal.rb:203:in `dispatch'
    actionpack (3.2.1) lib/action_controller/metal/rack_delegation.rb:14:in `dispatch'
    actionpack (3.2.1) lib/action_controller/metal.rb:246:in `block in action'
    actionpack (3.2.1) lib/action_dispatch/routing/route_set.rb:66:in `call'
    actionpack (3.2.1) lib/action_dispatch/routing/route_set.rb:66:in `dispatch'
    actionpack (3.2.1) lib/action_dispatch/routing/route_set.rb:30:in `call'
    journey (1.0.3) lib/journey/router.rb:68:in `block in call'
    journey (1.0.3) lib/journey/router.rb:56:in `each'
    journey (1.0.3) lib/journey/router.rb:56:in `call'
    actionpack (3.2.1) lib/action_dispatch/routing/route_set.rb:589:in `call'
    actionpack (3.2.1) lib/action_dispatch/middleware/best_standards_support.rb:17:in `call'
    rack (1.4.1) lib/rack/etag.rb:23:in `call'
    rack (1.4.1) lib/rack/conditionalget.rb:25:in `call'
    actionpack (3.2.1) lib/action_dispatch/middleware/head.rb:14:in `call'
    actionpack (3.2.1) lib/action_dispatch/middleware/params_parser.rb:21:in `call'
    actionpack (3.2.1) lib/action_dispatch/middleware/flash.rb:242:in `call'
    rack (1.4.1) lib/rack/session/abstract/id.rb:205:in `context'
    rack (1.4.1) lib/rack/session/abstract/id.rb:200:in `call'
    actionpack (3.2.1) lib/action_dispatch/middleware/cookies.rb:338:in `call'
    activerecord (3.2.1) lib/active_record/query_cache.rb:64:in `call'
    activerecord (3.2.1) lib/active_record/connection_adapters/abstract/connection_pool.rb:443:in `call'
    actionpack (3.2.1) lib/action_dispatch/middleware/callbacks.rb:28:in `block in call'
    activesupport (3.2.1) lib/active_support/callbacks.rb:405:in `_run__2985483728309837116__call__1908674296767231568__callbacks'
    activesupport (3.2.1) lib/active_support/callbacks.rb:405:in `__run_callback'
    activesupport (3.2.1) lib/active_support/callbacks.rb:385:in `_run_call_callbacks'
    activesupport (3.2.1) lib/active_support/callbacks.rb:81:in `run_callbacks'
    actionpack (3.2.1) lib/action_dispatch/middleware/callbacks.rb:27:in `call'
    actionpack (3.2.1) lib/action_dispatch/middleware/reloader.rb:65:in `call'
    actionpack (3.2.1) lib/action_dispatch/middleware/remote_ip.rb:31:in `call'
    actionpack (3.2.1) lib/action_dispatch/middleware/debug_exceptions.rb:16:in `call'
    actionpack (3.2.1) lib/action_dispatch/middleware/show_exceptions.rb:56:in `call'
    railties (3.2.1) lib/rails/rack/logger.rb:26:in `call_app'
    railties (3.2.1) lib/rails/rack/logger.rb:16:in `call'
    actionpack (3.2.1) lib/action_dispatch/middleware/request_id.rb:22:in `call'
    rack (1.4.1) lib/rack/methodoverride.rb:21:in `call'
    rack (1.4.1) lib/rack/runtime.rb:17:in `call'
    activesupport (3.2.1) lib/active_support/cache/strategy/local_cache.rb:72:in `call'
    rack (1.4.1) lib/rack/lock.rb:15:in `call'
    actionpack (3.2.1) lib/action_dispatch/middleware/static.rb:53:in `call'
    railties (3.2.1) lib/rails/engine.rb:479:in `call'
    railties (3.2.1) lib/rails/application.rb:220:in `call'
    rack (1.4.1) lib/rack/content_length.rb:14:in `call'
    railties (3.2.1) lib/rails/rack/log_tailer.rb:14:in `call'
    rack (1.4.1) lib/rack/handler/webrick.rb:59:in `service'
    /usr/share/ruby-rvm/rubies/ruby-1.9.2-p290/lib/ruby/1.9.1/webrick/httpserver.rb:111:in `service'
    /usr/share/ruby-rvm/rubies/ruby-1.9.2-p290/lib/ruby/1.9.1/webrick/httpserver.rb:70:in `run'
    /usr/share/ruby-rvm/rubies/ruby-1.9.2-p290/lib/ruby/1.9.1/webrick/server.rb:183:in `block in start_thread'

Request

Parameters:

{"region"=>"2",
     "categorie"=>"-1",
     "millesim"=>"-1",
     "price_from"=>"",
     "price_to"=>"-1",
     "cart_action"=>"-1",
     "to_add"=>"-1",
     "show_cart"=>"-1"}

Show session dump

_csrf_token: "kDD3qIZpvZInGWKclqSUQoyraIkcs20VKbhBMBZezJ4="
    cart: #<Cart:0x00000005ce0a68 @items=[[#<CsaV3Prd prod_wid: 6024, prod_cid: 907509, prod_pxuttc: #<BigDecimal:5ce07e8,'0.36E2',9(18)>>]], @total_price=0>
    session_id: "7efaefcb7af5aa99d68c7466c1e7ee4c"

---

In my controller I have my cart ' Initialization ' as needed.

class CataloguesController < ApplicationController
      def index
        @cart = find_cart
        @items = @cart.items
      end
    end

Here is my Cart Model:

class Cart
      attr_reader :items

      def initialize
        @items = []
        @total_price = 0
      end

      def add_product(product)
        @items << product
        product
      end

      def total_price
        @items.sum{ |item| item.prod_pxuttc}
      end

      def total_items
        @items.length
      end
    end

I don't understand why on this app the action ' total _ price ' don't work. My other app work fine with the same model.

The only difference between the two apps is that:

• on the Not-Working app, the column for the item price is ' decimal(10,2) ' type.
• on the Working app, the column for the item price is ' int(11) ' type.

And the most strange thing is that I can sort and render the column '*prod_pxuttc*' from the table into a listing. It renders the value.

Here is the two differents order to sort the same value from the table:

• First method (working and rendering the value): (this order sorts many items)

@prod = CsaV3Prd.find(:all,{:conditions=>["prod_cat = ?","#{params[:categorie]}"],:order=>"prod_cid DESC"})

• Second method (the cart method that doesn't work and call the error): (this order sort one unique item)

product = CsaV3Prd.find(:all,{:select=>["prod_wid, prod_cid, prod_pxuttc"],:conditions=>["prod_cid = ?","#{params[:to_add]}"],:order=>"prod_cid DESC"})

If someone know how to solve the problem, or if there is already a thread for this trouble (I searched and didn't find) please tell me.

Thanks.

EDIT 29-05-2012

Resolved

So the problem was about selecting an Array.

By selecting one single item to put into the cart, all works.

I replaced the parameter ':all' by ':first' .

Thanks to Frederick Cheung for his answer.

Answer 1

product = CsaV3Prd.find(:all,{:select=>["prod_wid, prod_cid, prod_pxuttc"],:conditions=>["prod_cid = ?","#{params[:to_add]}"],:order=>"prod_cid DESC"})

returns an array (possibly containing one element), not a single product. Use find :first if you only want one item.

You can also see this from the dump of the session you provided, where you can see that @items is an array of array (see how it starts with [[ ? )

Not related to your problem, but

:select=>["prod_wid, prod_cid, prod_pxuttc"]

working is probably an accident (due to what Array#to_s does), what you probably should be doing is

:select=>"prod_wid, prod_cid, prod_pxuttc"