[rails] Agile WebDev Cart Issue (Displaying Total Price)

[skeeterbug]

i am getting an error message that has me stumped. i cleared my cart, i cleared my cookies (which destroyed my original post and forced me to relogin here - ugggh!), i verified the code three times and it matches the book.

i'm at a loss.

here goes:

error message:

undefined method `total_price' for #<Cart:0xb7898594>
...
NoMethodError in Store#add_to_cart
...
12:     <td class="total-cell" ><%= number_to_currency(@cart.total_price) %></td>

the problem i'm having is that def total_price is in cart.rb.

cart.rb

class Cart

  attr_reader :items

  def initialize
    @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

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

end

add_to_cart.rhtml

<div class="cart-title" >Your Cart</div>
<table>
  <% for cart_item in @cart.items %>
    <tr>
      <td><%= cart_item.quantity %>&times;</td>
      <td><%= h(cart_item.title) %></td>
      <td class="item-price" ><%= number_to_currency(cart_item.price) %></td>
    </tr>
  <% end %>
  <tr class="total-line" >
    <td colspan="2" >Total</td>
    <td class="total-cell" ><%= number_to_currency(@cart.total_price) %></td>
  </tr>
</table>
<%= button_to "Empty cart" , :action => :empty_cart %>

the offending code is

@cart.total_price

if i remove it, the script runs, but, obviously, the total price doesn't display.

if it helps the debug process, i'm using the price_in_cents plugin.

i'm stumped - can anyone point me in the right direction?

as always, tia...

[vgarcia]

Did you reload the cart model after you made the change? Non-ActiveRecord models don't automatically reload from my understanding.

[skeeterbug]

Did you reload the cart model after you made the change? Non-ActiveRecord models don't automatically reload from my understanding.

vgarcia, i'm not sure how to reload the cart model so i stopped webrick and restarted it. will that reload the cart model?

after doing so, i'm receiving a new error message:

undefined method `sum' for #<Array:0xb793d290>

cart.rb

class Cart

  attr_reader :items

  def initialize
    @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

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

end

add_to_cart.rhtml

<div class="cart-title" >Your Cart</div>
<table>
  <% for cart_item in @cart.items %>
    <tr>
      <td><%= cart_item.quantity %>&times;</td>
      <td><%= h(cart_item.title) %></td>
      <td class="item-price" ><%= number_to_currency(cart_item.price) %></td>
    </tr>
  <% end %>
  <tr class="total-line" >
    <td colspan="2" >Total</td>
    <td class="total-cell" ><%= number_to_currency(@cart.total_price) %></td>
  </tr>
</table>
<%= button_to "Empty cart" , :action => :empty_cart %>

i'm thinking that maybe the price_in_cents plugin requires slightly different code, but i'm not sure what that would be. "price" is the price in dollars and "price_in_cents" is the price in cents.

btw, how does one reload a model within webrick (assuming it was loaded when i restarted webrick)?

as always, tia...

[skeeterbug]

now that i got a chance to search the error, thi s code fails b/c i'm not running rails 1.2 via edge rails.

vgarcia, thanks for the tip to reload the non-db model so i could get the right error message. i'm surprised the others missed mentioning this. either that or i missed reading it..

i think the code is code and can't debug it until 1.2 comes out or until i go with edge rails.

[johnroodt]

skeeterbug, I have updated to Rails 1.2 but still have the same issue you have. I am using Ruby 1.8.5, does anyone know if that may be the problem? The second edition of "Agile Web Dev with Rails" recommended using 1.8.4. Also, I used InstantRails to setup my environment and then updated to Rails 1.2 (beta)

What is more, when I look in the Ruby Documentation I don't see a "sum" method for Array...am I correct? That may explain why we are both getting the error:
"undefined method `sum' for #<Array:0xb793d290>" :-)

See if you can wade through this fix dated 05/03/2006 by Ron Jefferies who says "Of course there is no sum method in Array..." about a third the way down the page:
http://www.xprogramming.com/xpmag/dbcBowlingVector.htm

But in the meantime, here is my -- rather naive -- temporary fix, but it works. In the Cart class, modify the the def total_price method...

FROM:
def total_price

@items.sum { |item| item.price }

end

TO:

def total_price

sum = 0
for item in @items

sum += Float(item.price)

end
return sum

end


I also tried:

def total_price

@items.inject(0) { |sum, item.price| sum + item.price}

end

but got the error: "CartItem can't be coerced into Fixnum"
If anyone knows how to resolve this please let me know.

Thanks

[skeeterbug]

skeeterbug, I have updated to Rails 1.2 but still have the same issue you have. I am using Ruby 1.8.5, does anyone know if that may be the problem? The second edition of "Agile Web Dev with Rails" recommended using 1.8.4. Also, I used InstantRails to setup my environment and then updated to Rails 1.2 (beta)

What is more, when I look in the Ruby Documentation I don't see a "sum" method for Array...am I correct? That may explain why we are both getting the error:
"undefined method `sum' for #<Array:0xb793d290>" :-)

See if you can wade through this fix dated 05/03/2006 by Ron Jefferies who says "Of course there is no sum method in Array..." about a third the way down the page:
http://www.xprogramming.com/xpmag/dbcBowlingVector.htm

But in the meantime, here is my -- rather naive -- temporary fix, but it works. In the Cart class, modify the the def total_price method...

FROM:
def total_price

@items.sum { |item| item.price }

end

TO:

def total_price

sum = 0
for item in @items

sum += Float(item.price)

end
return sum

end


I also tried:

def total_price

@items.inject(0) { |sum, item.price| sum + item.price}

end

but got the error: "CartItem can't be coerced into Fixnum"
If anyone knows how to resolve this please let me know.

Thanks

i recommend going with ruby 1.84 if it is recommended. it is recommended for a reason and will likely bite you later if it isn't biting you now.

this may solve the issue.

good luck.

[skeeterbug]

how does rails handle displaying dates in views?

scaffolding makes this behavior very easy, but i need to manually code the view and i'm not sure how to do it.

iow, i want to allow the user to enter a date and i'm guessing there is a rails way to do it.

if not, do i have to use the select - option method? if so, how do i set the default option values for year, month and day?

tia...

[Fenrir2]

You can do `date_select :variable, :attribute` or if you use form_for: `form.date_select :attribute`.

Edit:

def total_price
@items.inject(0) { |sum, item.price| sum + item.price}
end

but got the error: "CartItem can't be coerced into Fixnum"
If anyone knows how to resolve this please let me know.

{|sum, item.price| should be {|sum, item|.