Rails - Jun 2006 - Yet another problem with NoMethodError in Store#display_cart

Hi everybody,

I''ve search a lot on google to help me with this one without success. I
know that some people had the same problem as I have, but there
solutions doesn''t seems to work for me.

I''m trying to do the depot example in the AWDwR book. But now
I''m stock
with a problem that I can''t solve. I get this error:

<--- begin error here --->
NoMethodError in Store#display_cart

Showing app/views/store/display_cart.rhtml where line #4 raised:

You have a nil object when you didn''t expect it!
You might have expected an instance of Array.
The error occured while evaluating nil.size

Extracted source (around line #4):

1: <h1>Display Cart</h1>
2:
3: <p>
4: Your cart contains <%= @items.size %> items.
5: </p>
<--- end error here --->

Here is a copy/paste of my code:

<--- file store_controller.rb begin here --->
class StoreController < ApplicationController

  def index
	  @products = Product.salable_items
  end

  def add_to_cart
      product = Product.find(params[:id])
      @cart = find_cart
      @cart.add_product(product)
      redirect_to(:action => ''display_cart'')
  end

  def diplay_cart
      @cart = find_cart
      @items = @cart.items
  end

  private
  def find_cart
      session[:cart] ||= Cart.new
  end
end
<--- file store_controller.rb end here --->

<--- file application.rb begin here --->
class ApplicationController < ActionController::Base
    model :cart
    model :line_item
end
<--- file application.rb end here --->

<--- file cart.rb begin here --->
class Cart
    attr_reader :items
    attr_reader :total_price

    def initialize
        @items = []
        @total_price = 0.0
    end

    def add_product(product)
        @items << LineItem.for_product(product)
        @total_price += product.price
    end
end
<--- file cart.rb end here --->

<--- file line_item.rb begin here --->
class LineItem < ActiveRecord::Base
    belongs_to :product

    def self.for_product(product)
        item = self.new
        item.quantity = 1
        item.product = product
        item.unit_price = product.price
        item
    end
end
<--- file line_item.rb end here --->

<--- file display_cart.rhtml begin here --->
<h1>Display Cart</h1>

<p>
	Your cart contains <%= @items.size %> items.
</p>
<--- file display_cart.rhtml end here --->

Here is what I tried so far:
- Delete all the cache from my browser (I''m using Opera, but I also
tried Firefox)
- Delete all the cookies
- Check for typos
- Restart WEBrick
- Reboot my computer (I''m using Windows XP with mySQL 5.0.18 and RoR
1.2)

I have put some breakpoint() in my code. The ''Cart'' is
created, @items
is set correctly and the session is also working (inside
store_controller.rb). If I put a breakpoint() method inside the
''display_cart.rhtml'', at the prompt, I can see that the
''session[:cart]
variable is properly set, but the ''@items'' is set to
''nil''. It really
seems like the ''@items'' is not readable or not set from within
the
''display_cart.rhtml'' file. But I think that the
'':model cart'' line is
correctly set in my ''application.rb''.

Can somebody help me with this one?

Thanks a lot.

-- 
Posted via http://www.ruby-forum.com/.

On Jun 23, 2006, at 10:58 AM, erix wrote:
> Hi everybody,
>
> I''ve search a lot on google to help me with this one without  
> success. I
> know that some people had the same problem as I have, but there
> solutions doesn''t seems to work for me.
>
> I''m trying to do the depot example in the AWDwR book. But now
I''m
> stock
> with a problem that I can''t solve. I get this error:
>
> <--- begin error here --->
> NoMethodError in Store#display_cart
>
> Showing app/views/store/display_cart.rhtml where line #4 raised:
>
> You have a nil object when you didn''t expect it!
> You might have expected an instance of Array.
> The error occured while evaluating nil.size
>
> Extracted source (around line #4):
>
> 1: <h1>Display Cart</h1>
> 2:
> 3: <p>
> 4: Your cart contains <%= @items.size %> items.
> 5: </p>
> <--- end error here --->
>
Try changing the #display_cart method to:

   def diplay_cart
       @cart = find_cart
       @items = @cart.items || []
   end

This will solve the problem when @cart.items returns nil. However, f  
you previously called #add_to_cart and #display_cart still doesn''t  
display the items you added, then there''s a bug elsewhere.

cr

Chuck Remes wrote:
> On Jun 23, 2006, at 10:58 AM, erix wrote:
> 
>>
>>
>> 1: <h1>Display Cart</h1>
>> 2:
>> 3: <p>
>> 4: Your cart contains <%= @items.size %> items.
>> 5: </p>
>> <--- end error here --->
>>
> 
> Try changing the #display_cart method to:
> 
>    def diplay_cart
>        @cart = find_cart
>        @items = @cart.items || []
>    end
> 
> This will solve the problem when @cart.items returns nil. However, f
> you previously called #add_to_cart and #display_cart still doesn''t
> display the items you added, then there''s a bug elsewhere.
> 
> cr
Hi Chuck Remes,

I tried your code, but it wasn''t working either. I was still getting
the
same error. But I finally found the problem: a typo! Look at the name of 
the display_cart method: ''def diplay_cart'' instead of
''def
display_cart''. But you point me on the problem, because it
wasn''t
logical to get the same error after setting @items to [] if @cart.items 
was nil. At last, the @items.size was support to return 0. So I looked 
again in the function and then I saw it.

Thanks again!

-- 
Posted via http://www.ruby-forum.com/.

On Jun 23, 2006, at 11:39 AM, erix wrote:
> [snip]
> I tried your code, but it wasn''t working either. I was still  
> getting the
> same error. But I finally found the problem: a typo! Look at the  
> name of
> the display_cart method: ''def diplay_cart'' instead of
''def
> display_cart''. But you point me on the problem, because it
wasn''t
> logical to get the same error after setting @items to [] if  
> @cart.items
> was nil. At last, the @items.size was support to return 0. So I looked
> again in the function and then I saw it.
A typo! My eyes just glanced right over it... Good catch.

cr