Question

Trying to build a shopping cart based on the Agile Web Development 4th edition. The shopping cart is for selling t-shirts. The t-shirts have various size options, color options, and gender options. I want users to be able to select their options from lists, click “add to cart”, and have the matching t-shirt added to to the cart (in the form of a line_item).

I think I am SO close to getting this done. But not quite. Here are the relevant code snippets:

The Form (/_store.html.erb):

<div id="storefunctions">
<%= form_tag '/line_items/create', :id => "tshirt" do %>
<div>
    size:&nbsp;<%= render 'size_select' %>&nbsp;
    color:&nbsp;<%= render 'color_select' %>&nbsp;
    gender:&nbsp;<%= render 'gender_select' %>
    <%= hidden_field_tag(:message_content, @message.content) %></div
 <div> <%= submit_tag 'add to cart'  %></div>
<% end %>   

Line_items Controller (/line_items/create.rb)

def create
@cart      = current_cart
tshirt     = Tshirt.where("size = ? AND gender = ? AND color = ?", params[:size], params[:gender], params[:color])
@line_item = @cart.line_items.build(:tshirt_id => tshirt.id)

respond_to do |format|
  if @line_item.save
    format.html { redirect_to(@line_item.cart, :notice => 'Line item was successfully created.') }
    format.xml  { render :xml => @line_item, :status => :created, :location => @line_item }
  else
    format.html { render :action => "new" }
    format.xml  { render :xml => @line_item.errors, :status => :unprocessable_entity }
  end
end

end

When I click “add to cart” it says I have successfully added it to cart, but I can not access any information about the shirt. It says it is a nil.

Any help would be appreciated!

Answer 1

Model.where(...) is going to be an array of results, not a single result object, so you can’t call .id on it. You probably want Tshirt.where("size = ? AND gender = ? AND color = ?", params[:size], params[:gender], params[:color]).first