Question

I’ve created a shopping cart with line items that exist in the session object. I can’t figure out how I link to my shopping cart show page if the cart exists and just link to a ‘cart is empty’ page if it doesn’t. What am I missing? My code is below:

• Cart has_many line_items, & lineitems belongs to Cart

View Link
, I wasn’t sure what I should put here and where to define it for example… “if current_cart.empty? cart”, or “if @cart.line_items.empty? current_cart”, etc.

        <% if current_cart.line_items.empty?%>
        <%= link_to "cart", cart_path, :class =>'headertab' %>&nbsp;
    <% else %>
        <%= link_to "cart", cart_path(current_cart), :class =>'headertab' %>&nbsp;
    <% end %>

This gives me the following error:

Showing /Users/dave/rails_projects/EquiptMe/app/views/layouts/_headerexterior.html.erb where line #20 raised:

undefined local variable or method `current_cart' for #<#<Class:0x007fae841cc8e0>:0x007fae83339698>
Extracted source (around line #20):

17:         <li><%= link_to "browse gear", '/gear', :class =>'headertab' %></li>
18:         <li><%= link_to "join", '/signup', :class =>'headertab' %></li>
19:         <li>
20:         <% if current_cart.line_items.empty?%>
21:             <%= link_to "cart", cart_path, :class =>'headertab' %>&nbsp;
22:         <% else %>
23:             <%= link_to "cart", cart_path(current_cart), :class =>'headertab' %>&nbsp;

Routes

Outdoor::Application.routes.draw do
  resources :line_items

  resources :carts
.....

Application Controller

class ApplicationController < ActionController::Base
  protect_from_forgery

  private

  def current_cart
    Cart.find(session[:cart_id])
    rescue ActiveRecord::RecordNotFound
      cart = Cart.create
      session[:cart_id] = cart.id
      cart
  end
end

Carts Controller “Show”, “Destroy” & “Create”

 def show
    begin
    @cart = Cart.find(params[:id])
    rescue ActiveRecord::RecordNotFound
      logger.error "Attempt to access invalid cart #{params[:id]}"
      redirect_to '/gear', notice: 'Invalid cart'
    else
      respond_to do |format|
        format.html # show.html.erb
        format.json { render json: @cart }
      end
   end

  def destroy
    @cart = current_cart
    @cart.destroy
    session[:cart_id] = nil

    respond_to do |format|
      format.html { redirect_to carts_url, notice: 'Your cart is currently empty' }
      format.json { head :no_content }
    end
end

  def create
    @cart = Cart.new(params[:cart])

    respond_to do |format|
      if @cart.save
        format.html { redirect_to @cart, notice: 'Cart was successfully created.' }
        format.json { render json: @cart, status: :created, location: @cart }
      else
        format.html { render action: "new" }
        format.json { render json: @cart.errors, status: :unprocessable_entity }
      end
    end
  end

Line Items Controller “Create”

 def create
    @cart = current_cart
    gear = Gear.find(params[:gear_id])
    @line_item = @cart.add_gear(gear.id)

    respond_to do |format|
      if @line_item.save
        format.html { redirect_to @line_item.cart }
        format.json { render json: @line_item, status: :created, location: @line_item }
      else
        format.html { render action: "new" }
        format.json { render json: @line_item.errors, status: :unprocessable_entity }
      end
    end
  end
  end

Thanks for the help!

Answer 1

From your code, you always have a created Cart object. Your current_cart method, will always return new or previously created Cart object, so you have to link to cart_path(current_cart).

  <%= link_to "my cart", cart_path(current_cart), :class =>'headertab' %>

In another case, if you want to check if the cart is empty? In this case you have to use current_cart.line_items.empty?

Edited

To access current_cart in Views and Controllers add helper_method :current_cart declaration to ApplicationController.

Code update:

class ApplicationController < ActionController::Base
  protect_from_forgery

  private

  def current_cart
    Cart.find(session[:cart_id])
    rescue ActiveRecord::RecordNotFound
      cart = Cart.create
      session[:cart_id] = cart.id
      cart
  end
  helper_method :current_cart
end