NoMethodError in Store#add_to_cart

Hello - I am new to not only Ruby but programing in general. I have
been given this book “Agile Web D. with Rails” and told that it
will tell me everything I need to know. I am completely lost. I have
managed to get to page 99, but I have been stuck with this error for
days and since I have no knowledge of programing I don’t know what to do
from here. Can someone please help me.

NoMethodError in Store#add_to_cart

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

You have a nil object when you didn’t expect it!
The error occurred while evaluating nil.items

Extracted source (around line #4):


Your Pragmatic Cart


    4: <% for cart_item in @cart.items %>
  • <%= h(item.title) %>

  • 6: <% end %>

Any help would be greatly appreciated. I am sure this is a pretty
stupid question, but I have no clue what else to do but ask it!