How to properly implement nested forms?

Question

Ruby on Rails

I'll try to explain.
I have a list of products that looks like this:

- @shop.items.each do |item|
 = item.name

Inside the loop there is a form that should submit the edited data.
Those. there is a cycle that displays 5 items of goods, each of the goods can be edited.
Now I tried to do this, but it doesn't work.

= form_for [@shop, @item] do |f|
 = f.label :name
 = f.text_field :name

Writes First argument in form cannot contain nil or be empty
General view.

- @shop.items.each do |item|
 = item.name
 = form_for [@shop, @item] do |f|
 = f.label :name
 = f.text_field :name

Answer 1

[@shop, @item ] - I suspect one of these nil variables