Error in Heroku does not make sense, application runs fine locally. RecordNotFound

Question

My application seems to be running fine locally. All of my code seems correct. My error is telling me that it could not find a record.

I have a model called cart which is related to users through session variables, I use the current_cart helper method to relate users to their carts. My error and code is below:

error

2013-07-14T23:53:08.615652+00:00 heroku[web.1]: State changed from starting to up
2013-07-14T23:53:09.480513+00:00 app[web.1]: Started GET "/" for 108.2.221.210 at 2013-07-14 23:53:09 +0000
2013-07-14T23:53:09.514335+00:00 app[web.1]: Processing by ProductsController#index as HTML
2013-07-14T23:53:09.622655+00:00 app[web.1]: Completed 404 Not Found in 108ms
2013-07-14T23:53:09.624409+00:00 app[web.1]: 
2013-07-14T23:53:09.624409+00:00 app[web.1]:   app/controllers/products_controller.rb:6:in `index'
2013-07-14T23:53:09.624409+00:00 app[web.1]:   app/controllers/application_controller.rb:20:in `current_cart'
2013-07-14T23:53:09.624409+00:00 app[web.1]: 
2013-07-14T23:53:09.624409+00:00 app[web.1]: 
2013-07-14T23:53:09.624409+00:00 app[web.1]: ActiveRecord::RecordNotFound (Couldn't find Cart with id=1):
2013-07-14T23:53:09.627892+00:00 heroku[router]: at=info method=GET path=/ host=pxdirect.herokuapp.com fwd="108.2.221.210" dyno=web.1 connect=1ms service=149ms status=404 bytes=728
2013-07-14T23:53:09.777019+00:00 heroku[router]: at=info method=GET path=/favicon.ico host=pxdirect.herokuapp.com fwd="108.2.221.210" dyno=web.1 connect=1ms service=10ms status=200 bytes=0

Products controller

  def index
          @products = Product.search(params)
      unless current_cart.nil?
          @cart = current_cart
      else
          @cart = nil
      end
  end

index view

 <% unless @cart.nil? %>
      <% if @cart.total_quantity > 0 %>
          <b>Cart&nbsp;(<%=@cart.total_quantity%>&nbsp;items)&nbsp;</b><i class="icon-shopping-cart"></i>
      <% else %>
          <b>Cart&nbsp;</b><i class="icon-shopping-cart"></i>
      <% end %>
 <% else %>
      <b>Cart&nbsp;</b><i class="icon-shopping-cart"></i>
 <% end %>

applicationcontroller

def current_cart
    if session[:cart_id]
          @current_cart ||= Cart.find(session[:cart_id])
          session[:cart_id] = nil if @current_cart.purchased_at
    end
    if session[:cart_id].nil?
      @current_cart = Cart.create!
      session[:cart_id] = @current_cart.id
    end
    @current_cart
  end

Any insight is appreciated

Answer 1

I suppose you have to handle ActiveRecord::RecordNotFound error:

def current_cart

  if session[:cart_id]
    begin
      @current_cart ||= Cart.find(session[:cart_id])
      session[:cart_id] = nil if @current_cart.purchased_at
    rescue ActiveRecord::RecordNotFound => e
      create_cart
    end
  else
    create_cart
  end

  @current_cart
end

def create_cart
  @current_cart = Cart.create!
  session[:cart_id] = @current_cart.id
end

This could be caused by invalid session data.